STUDY OF COMPOUNDS FROM EXTRACT OF Melochia umbellata (Houtt.) Stapf var. Degrabrata K. (PALIASA) LEAVES THAT HAS POTENTIAL AS ANTIBACTERIAL

Indonesia Chimica Acta Vol.8. No. 1, June 2015

Selfi, et.al.

ISSN 2085-014X

STUDY OF COMPOUNDS FROM EXTRACT OF Melochia umbellata (Houtt.) Stapf var. Degrabrata K. (PALIASA) LEAVES THAT HAS POTENTIAL AS ANTIBACTERIAL Selfi Wullur, Firdaus, Hasnah Natsir, dan Nunuk Hariani Soekamto1 Chemistry Departement, Faculty of Mathematics and Natural Sciences, Hasanuddin University, Makassar

Abstrak Telah dilakukan penentuan aktivitas antibakteri pada ekstrak daun M. umbellata (Houtt.) Stapf var. degrabrata K. terhadap tiga bakteri uji Escherichia coli, Staphylococcus aureus, dan Shigella dysenteriae, dengan amoksisilin sebagai kontrol positif dan DMSO sebagai kontrol negatif. Metode yang digunakan adalah difusi agar dengan media MHA (Muller Hinton Agar) pada variasi konsentrasi masing-masing ekstrak 2500 ppm, 5000 ppm, 10.000 ppm, dan 20.000 ppm. Ekstrak n-heksan merupakan ekstrak yang paling aktif terhadap bakteri S. aureus dengan zona hambatan sebesar 10,50 mm, 10,80 mm, 11,00 mm, dan 11,45 mm. Ekstrak yang paling aktif terhadap bakteri S. dysenteriae adalah ekstrak etil asetat dengan zona hambatan sebesar 9,36 mm, 11,55 mm, 11,58 mm, dan 17,70 mm. Isolasi senyawa dari ekstrak n-heksan diperoleh senyawa 1 berupa bubuk berwarna putih dengan titik leleh 75-77 ºC yang diidentifikasi sebagai 1-tetracosanol dan senyawa 2 yang berupa pasta berwarna kuning yang diidentifikasi sebagai senyawa golongan steroid yang memiliki substituen dengan konjugasi yang panjang. Senyawa-senyawa tersebut diidentifikasi berdasarkan data IR, UV-Vis, 1H-NMR, dan 13C-NMR. Kata kunci: 1-Tetracosanol, antibakteri, fitokimia, Melochia umbellata, steroid Abstract Determination of antibacterial activity of each extract of M. umbellata (Houtt.) Stapf var. K. degrabrata leaves has been conducted against three strains bacteria Escherichia coli, Staphylococcus aureus, and Shigella dysenteriae by using amoxicillin as a positive control and DMSO as a negative control. Agar diffusion method has been used with MHA medium (Muller Hinton Agar) on variation concentrations of each extract were 2500 ppm, 5000 ppm, 10,000 ppm, and 20,000 ppm N-hexane extract was the most active extract against S. aureus with zone of inhibitions were 10.50 mm, 10.80 mm, 11.00 mm and 11.45 mm, respectively. The most active extract against S. dysenteriae was ethyl acetate extracts with zone of inhibitions were 9.36 mm, 11.55 mm, 11.58 mm and 17.70 mm, respectively. Isolated compound from n-hexane extract was first compound as white powder with a melting point of 75-77 °C which was identified as 1-Tetracosanol and second compound was obtained in the form of a yellow paste which was identified as steroid compound that had long conjugated substituent. These compounds were elucidated based on the data of IR, UV-Vis, 1H-NMR, and 13C-NMR. Keywords: 1-Tetracosanol, antibacterial, phytochemical, Melochia umbellata, steroid

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Adress for correspondence: [email protected]; mobile: +6281355116115

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Those plants have a genetic relationship with M. umbellata. In previous research, the methanol extract of the leaves of M. umbellata could inhibit the growth of Staphylococcus aureus and Shigella dysenteriae but could not inhibit the growth of Escherichia coli (Wullur, et al., 2013). Therefore, this study was conducted to find out the ability of various types of other extracts from the leaves of M. umbellata against S. aureus and S. dysenteriae, as well as compounds that could be isolated from the active extracts.

INTRODUCTION Sterculiaceae is a plant family which consists of about 70 genera and 1500 species spread throughout the world (Gressler, et al., 2008). In 2003, the Sterculiaceae family has been officially incorporated into the Malvaceae family as it has a very close relationship and difficult to be distinguish from long ago (APG, 2003). Plants of the Malvaceae family is known to be rich in alkaloids, particularly the cyclopeptide alkaloids, quinolinone, and isatin alkaloids (Dias, et al., 2007). It is associated with a previous study which was reported that the phytochemical test of methanol extract of M. umbellata Stapf var. degrabrata K (Malvaceae) showed positive results against alkaloids, flavonoids, steroids, and saponins (Wullur, et al., 2013). M. umbellata is traditionally known as wonolita by Munanese ethnic group and is used to treat itching and scabies (Windadri, et al., 2006). This plant is also known as bengkal by the tribe of Serawai Bengkulu and the leaves, bark, and roots are used to treat fever in Narmada, West Lombok (Hargono, 2000; Hadi and Bremner, 2001). In Brazil and India, other plant with the same genus are also used as traditional medicines. Water decoction of the leaves and roots of M. corchorifolia L. is used to treat dysentery (Shanmugam, et al., 2011; Batugal, et al., 2004). Leaves of M. pyramidata L are used traditionally in the eastern region of Brazil to treat coughs and bronchitis. Based on further analysis, dysentery and bronchitis can be caused by bacteria. Root extract of M. tomentosa was found to be oncogenic, while its water decoction is used to facilitate in the childbirth (Agra, et al., 2007; Kapadia, et al., 1977).

EXPERIMENTAL General Experimental Procedure Melting point was determined using Fisher John apparatus. IR spectra was obtained using Shimadzu FTIR 8501 spectrometer. UV-Vis spectrum was obtained using a UV-Vis Spectroscopy 2600 Shimadzu. 1H and 13 C NMR spectra were recorded at 500.0 / 125.65 MHz, on a JEOL JMN A 5000 spectrometer using CDCl3 as solvent and TMS as internal standard. Thin layer chromatography was performed on a pre-coated TLC plates (Merck, silica 60 F-254) which was monitored using UV lamp long and short, then was sprayed with Ce (SO4)2 2% in H2SO4 2N, followed by heating. Plant Material Plant material (leaves) was collected on April 2013 in Antang, South Sulawesi, Indonesia. Identification of the plant was done in Bogoriense Herbarium, Center for Biology Research and Development, LIPI Bogor with specimen number is BO-1912171. Extraction Fresh leaves of M. umbellata as much as ± 20 pieces were boiled in water for several hours then filtered, and the filtrate was concentrated to 2


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obtain a concentrated water extract. On the other hand, the fresh leaves of M. umbellata (Houtt.) Stapf var. degrabrata K. were air-dried and pulverized. Air-dried leaves powder (1 kg) were extracted with methanol (1 × 24 hours 7 times) at room temperature, then filtered. Removal of the solvent from the extract was performed under reduced pressure in a rotary evaporator to obtain a dark crude methanol extract (218 g). Concentrated methanol extract then was partitioned with n-hexane solvent in order to obtain the n-hexane extract (29.2 g). Methanol layer was further partitioned with chloroform and ethyl acetate in sequence in order to obtain the chloroform extract (22.7 g) and ethyl acetate extract (19.3 g).

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(1.0093 g) further was fractionated by gravity column chromatography (GCC). Fractionation resulted in 11 fractions. White precipitate formed on fraction C4.5 then was identified as compound 1. This compound did not fluoresce under UV long and short wave light, but appeared after was sprayed with Ce (SO4)2 2% in H2SO4 2 N and heated. Fraction C4.5 which had been separated from the dried compound 1 (0.3898 g) then was fractionated back with GCC and produced 5 fractions. Fraction C4.5.2 (0.1328 g) was fractionated back with GCC because it showed the strong presence of blue phosphorescent compound on TLC under UV long wave light. Fractionation produced 6 fractions but could not separate the blue glow. Fraction C4.5.2.3 (0.0145 g) was fractionated using preparative TLC with [n-hexane (4): CHCl3 (6)] eluent. Elution process was performed twice to separate well the blue fluorescent spot. Spots were tested for their purities and compound 2 (1.9 mg) was obtained.

Antibacterial Assay Antibacterial activity of n-hexane, chloroform, ethyl acetate, and water extracts were tested against S. aureus and S. dysenteriae using agar diffusion method with paper discs. The used microorganisms were pure cultures isolated from the Faculty of Medicine, Hasanuddin University. Antibacterial activity test used DMSO as solvent with various concentrations of each extract were 2,500, 5,000, 10,000 and 20,000 ppm. Incubation was carried out for 48 hours while a clear zone was measured every 24 hours. Amoxicillin is used as a positive control. Each test was performed 3 times.

Compound (1) 1-Tetracosanol Compound (1) was obtained as a white powder as much as 20.3 mg. Melting point 75-77 ºC. IR spectrum (KBr) ʋmaks (cm-1): 3446 (OH), 2918 and 2848 (CH aliphatic), 1467 (CH2), 1379 (CH3), 1060 (C-O). 1H-NMR (500 MHz, CDCl3), δH (ppm): 3,63 (H1, 2H, t, J = 6,5 Hz), 1,56 (H-2, 2H, p, J=7,1 Hz), 1,25 (H-3-23, 42H,m), 0,87 (H-24, 3H, t), 1,59 (OH, 1H, s). 13CNMR (125 MHz, CDCl3), δ (ppm): 63,30 (C-1), 32,99 (C-2), 25,92 (C-3), 29,62 (C-4), 29,80 (C-5), 29,88 (C-6-C20), 29,55 (C-21), 32,11 (C-22), 22,88 (C-23), 14,32 (C-24).

Isolation N-hexane extract (11.31 g) was fractionated by vacuum column chromatography (VCC) with increased polarity of n-hexane, ethyl acetate, acetone and methanol eluents to obtained six major factions. The main fraction 3 (fraction C, 8.05 g) was further fractionated back with VCC yielded 19 fractions. Fraction C4

Compound (2) Compound (2) was obtained as a yellow paste as much as 1.9 mg. Positive steroid with LiebermannBurchard reagent. UV-Vis spectrum 3


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(CHCl3) λmaks (nm): 239 and 342, (C2H5OH) λmaks (nm): 202, 221, and 344. IR spectrum (KBr) ʋmaks (cm-1):

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3444 (OH), 2954 and 1381 (CH3), 2922 and 2852 (CH aliphatic), 1641 (C=C), 1462 (CH2), 1043 (C-O).

Table 1. Antibacterial activity of each extract of leaves M. umbellata (Houtt.) Stapf var. degrabrata K. Extract

Concentration .ppm 2.500 5.000 10.000 Methanol 20.000 PC NC 2.500 5.000 10.000 n-Hexane 20.000 PC NC 2.500 5.000 10.000 Chloroform 20.000 PC NC 2.500 5.000 10.000 Ethyl acetate 20.000 PC NC 2.500 5.000 10.000 Water 20.000 PC NC Specification: n.i: not inhibit PC: Amoxicillin NC: DMSO

Diameter of Inhibition Zone (mm) S. dysenteriae S. aureus 7,55 6,95 8,30 7,73 10,10 8,52 13,25 9,90 26,90 16,43 n.i n.i 7,48 10,50 7,50 10,80 7,65 11,00 7,76 11,45 25,50 19,75 n.i n.i 7,30 9,30 7,53 10,10 7,96 10,40 8,53 10,50 26,73 19,10 n.i n.i 9,36 10,10 11,55 10,55 11,58 10,80 17,70 10,80 24,56 18,70 n.i n.i n.i n.i n.i n.i n.i 8,23 n.i 8,78 26,41 16,00 n.i n.i

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RESULTS AND DISCUSSION Antibacterial Potential of M. umbellata (Houtt.) Stapf var. degrabrata K. Leaves Extract Before continue to the isolation stage, an analysis was conducted towards antibacterial activity of some leaves extracts of M. umbellata, in this study were water, n-hexane, chloroform, and ethyl acetate extract. Antibacterial activity assay of those extracts were done by measuring the diameter of inhibition zone with agar diffusion method and using the paper disc. Diameter data of inhibition zone of each leaf extract can be seen in Table 1. Methanol (Wullur, et al., 2013) and water extracts did not have activity against E. coli. Therefore, the assay for that bacteria was not conducted for other extracts. Based on the data of antibacterial activity presented in Table 1, it could be concluded that the n-hexane extract was the most active against S. aureus, and the ethyl acetate extract was the most active against the S. dysenteriae. Traditionally, water decoction of the leaves and roots M. corchorifolia taken three times over two days to cure dysentery (Shanmugam, et al., 2011). The obtained data in Table 1, indicated that the methanol, n-hexane, chloroform, and ethyl acetate extract of the leaves M. umbellata could inhibit the growth of S. dysenteriae. Therefore, the leaves of M. umbellata had the potential to cure dysentery like leaves M. corchorifolia. Based on these data, all various extracts of the leaves M. umbellata could also inhibit the growth of S. aureus but could not inhibit the growth of E. coli. Therefore, leaves M. umbellata could be used also to cure a disease caused by S. aureus.

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Compound (1) 1-Tetracosanol Compound 1 (20.3 mg) was obtained as a white powder with a melting point of 75-77 °C. This compound was soluble in chloroform and insoluble in acetone at room temperature and did not fluoresce under UV long and short wave light. This indicated that this compound did not have conjugated double bond. 1 H-NMR spectrum of compound 1 showed five peaks. The spectrum showed the presence of a signal at δH 3.63 ppm (H-1, 2H, t, J = 6.5 Hz) indicated as a methylene protons attached to the hydroxyl group. While at δH 1.57 ppm (H-2, 2H, p, J = 7.1 Hz) was a methylene protons attached to two methylene group. At δH 1.59 ppm were signals that overlapped with the signal δH 1.57 ppm. ΔH 1.59 ppm signal was an OH singlet signal that would increasingly shift to high field magnetic field as the longer of the carbon chain. While the signal δH 0.87 ppm (H-24, 3H, t, J = 6.8 Hz) was a methyl protons bound to a methylene group. At the signal δH 1.25 ppm (H-3-23, 42h, m) showed some methylene group which had the same conditions on a straightchain, so it had a very high signal intensity. If the number of protons in this signal was determined by its integration, it gained more than 20 protons. Based on the 1 H-NMR data, the compound structure could be assumed as straight chain alcohols. If the melting point of the compound was reviewed, the obtained melting point was as same as alcohol’s containing 24 carbons (Guidechem, 2012). 13 C-NMR spectrum of this compound showed 10 signals 5


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representing 24 carbon atoms which included one oxy carbon (C-1) alcohol at δC 63.3, eight methylene signals (C-2 and C-3 and C-4 and C-5 ; C-6-20 and C-21 and C-22 and C-23), and the methyl signal at δC 14.3 (C-24). Based on the spectroscopic data structure of compound 1 could be formulated as in Figure 1. IR spectral data of compound 1 which indicated the presence of the C = C olefins were not supported by the data of 1H-NMR and 13C-NMR

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spectrum since signal at chemical shift 4.5-6.5 ppm in the 1H-NMR spectrum did not appeared and so did signal at chemical shift 100-150 ppm in the 13 C-NMR spectrum. Relationship bonds in the structure was evidenced by HMQC and HMBC spectra. HMBC and HMQC analysis results were shown in Table 2. Figure 1 showed an illustrative analysis of HMBC and Figure 2 showed the analysis of HMQC based on the structure.

Table 2. Data of 1H, 13C, and 2D NMR spectrum of compound 1 1

H-1H COSY 2

1

1

δ H (H, multiplicity, J in δC Hz (ppm) 3,63 (2H, t, 6,5) 63,3

2

1,57 (2H, p, 7,1)

1,3

C-2

Position

3 4 5 6-20 21 22 23 24 OH

25,9 29,6 29,8 29,9 29,5 32,1 22,9 14,3 -

1,25 (42H, m)

0,87 (3H, t, 6,8) 1,59 (1H, s)

H

H

H

H

H

C H

32,9

C

(CH 2) 15

C H

H

H H

C

C

C

C

H

H

H

H

H

H C

OH C

H H

H

Figure 1. The results of HMBC analysis of Compound 1 H

H H

C H

H H

C C

H

H (CH 2)15

C

C

C

H

H

H H

H H

H C

C H

OH C

H H

H

Keterangan: COSY HMQC

Figure 2. The results of COSY and HMQC analysis of Compound 1 6

H-13C HMQC C-1

1

H-13C HMBC C-2, C-3 C-1, C-3, C-4, C-5 C-23, C-22 -

2 24,22 C-23 23 C-24 Compound (2) Compound 2 (1.9 mg) was obtained in the form of a yellow paste and soluble in methanol, chloroform and acetone at room temperature. These compounds fluoresced under UV long wave light and did not fluoresce under UV short wave light. It indicated that this compound had a conjugated double bond that emitted bright blue fluorescence under UV long-wave light. UV-Vis spectral data with ethanol as the solvent showed 3 maximum wavelengths at 202.5, 221, and 344 nm. Ethanol had a maximum wavelength at 205 nm (Pavia, et al., 2001). Therefore, it could be determined that the maximum


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wavelength at 202.5 nm, was a maximum wavelength of ethanol. While the UV-Vis spectrum of other data using chloroform as the solvent showed 2 maximum wavelengths at 239 and 342 nm. Chloroform had a maximum wavelength at 173 nm, so it did not appear in the used wavelength range. Both of UV-Vis spectra showed lower maximum wavelength at <250 nm with a high intensity was π → π * transition. While the higher maximum wavelength at > 300 nm with a low intensity was n → π * transition. Each transition indicated the presence of π system or a double bond and the lone pair electron (Pavia, et al., 2001). Based on this, conjugation between π system and the lone pair electron could be happened. If those UV-Vis spectras were compared, a shift to lower wavelength was occurred. The shift was a hypsochromic (blue shift) that occured with increasing polarity of the solvent. Based on the results of the test group, the spectrum of UV-Vis and IR spectra of compounds 2, it was assumed as a steroid derivative compounds which had long conjugation.

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ACKNOWLEDGEMENTS This study was supported by the Student Creativity Program (CRP) for financial support and BogorienseHerbarium, Research Center and Biology Development, LIPI Bogor for plant identification. Thanks for the help for Mr. Marcus Lembang on antibacterial activity assay carried out in the Laboratory of Microbiology, Faculty of Medicine, Hasanuddin University, and Mr. Ahmad Darmawan, M.Sc., Chemical Research Center staff, LIPI Serpong, Tangerang, who had helped in the measurement of NMR spectra. REFERENCE 1. Agra, M. F., Freitas, P.F., BarbosaFilho, J. M., “ Synopsis of the Plants Known As Medicinal and Poisonous in Northeast of Brazil”, Brazilian Journal of Pharmacognosy, vol. 17, no. 1, hal 114-139, 2007. 2. APG (Angiosperm Phylogeny Group), “An Update of the Angiosperm Phylogeny Group Classification for the Orders dan Families of Flowering Plants, APG II”, Botanical Journal of the Linnear Society, vol. 141, no. 4, hal.399-436, 2003. 3. Batugal, P. A., Kanniah, J., Young, L. S., and Oliver, J. T, “Medicinal Plants Research in Asia”, Volume 1: The Framework and Project Workplans. International Plant Genetic Resources InstituteRegional Office for Asia, the Pacific and Oceania (IPGRI_APO), Serdang, Selangor DE. Malaysia, 2004. 4. Dias, G.C.D., Gressler, V., Hoenzel, S.C.S.M., Silva, U.F., Dalcol, I.I., and Morel, A.F., “Constituents of the Roots of Melochia chamaedrys”, Phytochemistry, vol. 68, hal.668672, 2007.

CONCLUSION Ethyl acetate extract was the most active extract against S.dysenteriae with zone of inhibition from concentration of 2500, 5000, 10,000, 20,000 ppm were 9.36, 11.55, 11.58, and 17.70 mm respectively. While n-hexane extract was the most active against the growth of S. aureus with zone of inhibition were 10.50, 10.80, 11.00 and 11.45 mm respectively. Two compounds that could be isolated from n-hexane extract of the leaves M. umbellata (Houtt.) Stapf var. Degrabrata K were 1-Tetracosanol and conjugated steroid. 7


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5. Gressler, V., Stuker, C.Z., Dias, G.O.C., Dalcol, I.I., Burrow, R.A., Schmidt, J., Wessjohann, L., and Morel, A.F., “Quinolone Alkaloids from Waltheria douradinha”, Phytochemistry, vol. 69, hal.994999, 2008. 6. Guidechem, 2012, 1-Tetracosanol Density, Molecular Structure, Formula, Synonyms, Boiling point, Flash Point, Storage Temperature, (Online), (http://www.guidechem.com/diction ary/en/506-51-4.html, diakses 15 Mei 2014). 7. Hadi, S., and Bremner, J.B., “Initial Studies on Alkaloids from Lombok Medicinal Plants”, Molecules, Vol. 6, hal 117-129, 2001. 8. Hargono, D., “Obat Analgetik dan Antiinflamasi Nabati”, Cermin Dunia Kedokteran, No. 129, hal.3638, 2000. 9. Kapadia, G.J., Shukla, Y.N., Morton, J.F., and Lloyds, H.A., “New Cyclopeptide Alkaloids from Melochia tomentosa”, Phytochemistry, vol. 16, hal. 14311433, 1977. 10. Pavia, D.L., Lampman, G.M., and Kriz, G.S., 2001, Introduction to Spectroscopy. A guide for student of organic chemistry Third Edition, Thomson Learning Inc., United States. 11. Shanmugam, S., Kalaiselvan, M., Selvalumar, P., Suresh, K., and Rajendran, K., “Ethnomedicinal Plants Used to Cure Diarrhoea and Dysentery in Sivagangai District of Tamil Nadu, India”, International Journal of Research in Ayurveda & Pharmacy, vol. 2, no. 3, hal. 991994, 2011. 12. Windadri, F.L., Rahayu, M., Uji, T., and Rustiami, H., “Uses of Plants as Medicine by Muna People, Sub District Wakarumba, District Muna,

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Province of Southeast Sulawesi”, Biodiversitas, vol. 7, no. 4, hal.333339, 2006. 13. Wullur, S., Soekamto, N.H., Zenta, F., dan Natsir, H., “Uji Fitokimia dan Potensi Antibakteri dari Ekstrak Daun Melochia umbellata (Houtt.) Stapf var. Degrabrata K.”, Prosiding Simposium Nasional Kimia Bahan Alam XXI, Makassar, 2013.

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ADSORPTION RATE CONSTANTS OFEOSININ HUMIN Anshar, A.M.,* Santosa. S.J.,** and Sudiono. S.,** *Chemistry Department, Faculty of Mathematics and Natural Science Hasanuddin Univ. Makassar 90254 ** Chemistry Department, Faculty of Mathematics and Natural Science Gadjah Mada Univ. Yogyakarta 90254 *Email :[email protected] ABSTRACT Eosin is one of the dyescomm only used in the industry and has the potential to cause pollution of the water environment. The Eosin pollution treatment methods used in this study wasthe adsorption method using huminfr action obtained from the peatl and comes from Kalimantan. From the research data showed that the adsorption of eosin in humin result of washing with HCl/HF optimumat pH 4 and a contact time of 60 minutes with the adsorption-order rate was 8,4 x 10-3 min-1 Key Words : adsorption, eosin, humic, peat. Muna, 2014), Elektrokimia (marlena,

2012), kombinasi metode karbon aktif dan foto katalisis (Riyani dan Setyaningtyasnamun, 2011)namun metode tersebut belum mampu memberikan hasil yang optimal. Oleh karena itu perlu dicari metode lain yang dapat memecahkan permasalahan pencemaran zat warna terhadap lingkungan perairan tanpa harus mengeluarkan biaya yang besar dan dengan menggunakaan bahan-bahan yang tersedia di alam. Salah satu metode yang biasa digunakan untuk mengadsorp limbah organik khususnya zat warna yaitu dengan menggunakan humin yang merupakan salah satu fraksi dari senyawa humat. Keberadaan bahan humat tersebar di lingkungan, di semua tanah, perairan dan sediment di lapisan bumi (Gaffeey, 1996). Menurut Aiken, dkk (1985) ada 3 fraksi terbesar dari senyawa humat yang dapat dibedakan berdasarkan kelarutannya yaitu : 1. Humin adalah fraksi dari senyawa humat yang tidak larut dalam air pada semua nilai pH. 2. Asam humat adalah fraksi dari senyawa humat yang tidak larut dalam air padakondisi asam tapi mudah larut pada pH yang tinggi. 3. Asam fulvat adalah fraksi dari senyawa asam humat yang dapat larut pada berbagai nilai pH . Di lingkungan, humin merupakan fraksi terbesar penyusun senyawa humat dan cara memperolehnya juga relatif mudah (Stevenson, 1994). Penelitian yang dilakukan oleh Ishiwatari (1985) di beberapa danau di Jepang memberikan

Pendahuluan Perkembangan industri dewasa ini di Indonesia semakin pesat. Berbagai macam industri didirikan untuk memenuhi kebutuhan masyarakat di berbagai bidang. Salah satu industri yang saat ini berkembang adalah industri yang menggunakan zat warna dalam menghasilkan produknya seperti pewarnaan serat selulosa, sutra, wol, nilon dan kulit pada industri tekstil (Razae,2008) maka hal tersebut dapat menimbulkan efek samping berupa peningkatan kuantitas limbah zat warna. Peningkatan jumlah ini perlu diwaspadai karena pelepasan limbah zat warna ke lingkungan perairan seperti sungai (Rahmawati, 2011), danau dan lainnya akan menyebabkan terjadinya polusi yang berbahaya dan menjadi sumber gangguan kehidupan perairan sehingga diperlukan upaya penanganan yang serius. Dari sekian banyak bahan pencemar yang ada dan dikenal orang dewasa ini, zat warna eosin merupakan zat warna yang cukup berbahaya bagi kesehatan manusia (Hamdaoui dan Chiha, 2006) yang sering digunakan di dalam industri selain metilena biru (Anshar, 2014). Upaya penanganan masalah pencemaran zat warna ini sudah banyak dicoba misalnya dengan menggunakan metode adsorpsi untuk mengadsorp zat warna tersebut dengan menggunakan adsorben karbon aktif (lawakka, 2005) atau karbon aktif, kitosan (Mahatmanti dan Sumarni, 2003) (Tanasale, 2012),Kitosan-Bentonit (

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hasil 17% asam humat, 11% asam fulvat dan 67% humin. Meskipun asam humat dan asam fulvat juga berpengaruh namun humin merupakan fraksi yang memegang peranan penting karena eosinakan berinteraksi dengan bahan organik dan bahan mineral yang terdapat pada humin. Hal ini didasarkan pada pendapat bahwa humin dapat dipandang sebagai polielektrolit makromolekuler yang tidak larut dalam asam maupun basa dan memiliki gugus utama–COOH dan gugus –OH (fenolat) (Kaled. H,, dan and Fawy H., A., 2011) sehingga humin dapat berinteraksi membentuk ikatan dengan eosin. Berbagai penelitian tentang interaksi humin dengan sejumlah kontaminan telah dilakukan oleh beberapa ahli terutama kontaminan organik, seperti hidrokarbon poliaromatis(PAHs) dan poliklorobifenil (BCBs) yang berlangsung relatif cepat dan dalam beberapa kasus bersifat ireversibel.Dalam penelitian ini dipelajariinteraksi antara humin dengan eosin sebagai suatu senyawa organik yang keberadaannya di lingkungan perairan biasanya dalam bentuk limbah zat warna.

Isolasi humin dilakukan dengan menggunakan metode ekstraksi menggunakanNaOH 0,1 M selama 24 jam dalam kondisi atmosfer nitrogen. Untuk menghilangkan bahan-bahan anorganik seperti silika, lempung dan logam digunakan larutan campuran 0,1 M HCl dan 0,3 M HF. 2. Prosedur penetapan kadar abu humin Lima puluh miligram humin netral, humin dengan pemurnian HCl/HF dimasukkan ke dalam cawan porselin lalu dipanaskan dalam tungku (furnace) pada temperatur 750oC selama 4 jam.Berat sampel awal sebelum dan sesudah dipanaskan dicatat.Masing-masing sampel dilakukan dengan 3 kali pengukuran (tripel). 3. Penetapan komposisi kuantitatif gugus –COOH dan –OH fenolat. Kandungan komposisi kuantitatif humin yang dilakukan dalam penelitian ini adalah keasaman total dan kandungan gugus karboksilat. Penentuan gugus –OH fenolat ditentukan dengan menghitung selisih keasaman total dan kandungan gugus – COOH.

Metoda Penelitian 3.1 Penetapan kandungan keasaman total Seratus miligram humin dimasukkan ke dalam labu takar 100 mL dan di tambah 20 mL larutan jenuh Ba(OH)2 sambil dialiri gas nitrogen. Setelah dialiri gas nitrogen, labu takar ditutup dan digojog selama 24 jam pada temperatur kamar. Secara simultan dilakukan pula terhadap larutan blangko yang hanya mengandung 20 mL larutan jenuh Ba(OH)2. Suspensi yang terbentuk disaring dengan kertas saring whatman 42 dan residu dibilas dengan air destital bebas CO2. Filtrat dan air bilasan digabung lalu dititrasi secara potensiometri dengan larutan standar 0,5 M HCl hingga pH 8,4. Harga keasaman total (cmol/kg) ditentukan dengan persamaan:

Alat dan Bahan Alat penelitian yang digunakan adalah Kertas pH, kertas saring biasa, kertas saring Whatmant 42, spectrometer UV-vis Hitachi 150-20, spektrometer inframerah Shimadzu FTIR-820IPC, shaker, furnace karbolit, alat titrasi, pH meter Orion model 290A, ayakan, timbangan digital, peralatan plasik seperti botol plastik gelap, labu takar berbagai ukuran, cawan porselin, alat–alat gelas yang ada di Lab. Kimia Fisika dan Lab. Anorganik UGM. Bahan yang digunakan yaitu tanah gambut dari Pontianak serta bahan kimia berupaeosin, natrium hidroksida (NaOH) 0,1 M, asam klorida (HCl) pekat 37,5 %, asam klorida (HCl) 0.1 M, asam flourida (HF) 0,3 M, barium hidroksida(BaOH.8H2O), kalsium asetat (Ca (CH3COO)2 ), asam klorida 0,5 % ( E merck) , Gas N2 (PT Samator Gas), air destilat bebas CO2 dan aquades

(

−

)

10

/

dengan: Vb =Volume larutan standar asam yang digunakan untuk titrasi blanko Vs =Volume larutan standar asam yang digunakan untuk titrasi sampel N =Normalitas larutan standar asam

Prosedur Kerja 1. Isolasi Humin

3.2 Penetapan kandungan gugus karboksilat

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Seratus miligram humin dimasukkan ke dalam labu takar 100 mL lalu ditambahkan larutan 10 mL Mg(CH3COO)2 0,5 M dan 40 mL air destilat bebas CO2. Secara simultan disiapkan pula blanko yang hanya mengandung 10 mL larutan Mg(CH3COO)2 0,5 M dan 40 mL air distilat bebas CO2 kemudian digojog selama 24 jam pada temperatur kamar. Suspensi yang terbentuk disaring dengan kertas saring whatman 42. Residu dibilas dengan air destilat bebas CO2. Filtrat dan air bilasan digabung lalu dititrasi secara potensiometri dengan larutan standar 0,1 M NaOH hingga pH 9,8.Percobaan tersebut dilakukan dengan 2 kali pengulangan. Kandungan gugus karboksilat lalu ditentukan dengan persamaan: (

)

5 Penetapan waktu adsorpsi maksimum eosin Sebanyak masing–masing 50 mg humin diinteraksikan dengan 25 ml larutan eosindengan konsentrasi awal larutan eosin masing–masing 10 mg/L. Campuran diinteraksikan dengan cara di gojog dengan bantuan shaker pada pH optimum terjadinya adsorbsi dengan variasi waktu 2, 4, 6, 8, 10, 12, 15, 30, 60, 90, 120, 150, 180, 210, 240 menit. Setelah selesai filtrat dan endapan dipisahkan dengan disaring. Filtrat yang diperoleh kemudian dianalisis konsentrasi eosine dengan Spektofotometer UV-vis 6 Penentuan Kecepatan adsorpsi humin terhadap eosin Setelah mengetahui waktu optimum penyerapan humin terhadap eosin maka selanjutnya dibuat grafik banyaknya eosin yang teradsorp (mol/L) lawan waktu kontak (menit). Selanjutnya untuk menentukan besarnya laju adsorbat digunakan persamaan yang dibuat oleh Santosa (Anshar, 2014). Laju adsorpsi humin terhadap senyawa organik dapat kita ketahui dengan membuat plot :

/

dengan : Vb = Volume larutan standar basa yang digunakan untuk titrasi blanko Vs = Volume larutan standar basa yang digunakan untuk titrasi sampel N = Normalitas larutan standar basa

C  ln  A0   C A  lawan t yangmana akan dihasilkan CA CA

3.3 Penetapan kandungan gugus OH fenolat Gugus –OH fenolat merupakan selisih dari keasaman total dengan kandungan gugus –COOH sehingga kandungan gugus OH fenolat dapat ditentukan dengan persamaan : Gugus –OH fenolat = Selisih antara Keasaman total dengan gugus –COOH(Anshar,2014)

hubungan linier dengan slope = k1A dan intersep = KA.

4 Penetapan pH optimum adsorpsi eosin pada humin. Sebanyak masing–masing 50 mg humin diinteraksikan dengan 25 ml larutan eosin dengan konsentrasi larutan 10 mg/L yang merupakan hasil pengenceran dari larutan awal dengan konsentrasi 100 mg/L. Kemudian pH diatur dengan penambahan HCl atau NaOH sehingga di dapatkan nilai pH awal 2.0 ; 4,0 ; 6,0 ; 8,0 ; 10,0 ; 12,0 ; dan 14,0. Larutan yang telah diatur pH-nya kemudian digojog selama 120 menit dan didiamkan selama 24 jam untuk mencapai kesetimbangan. Setelah interaksi, filtrat dan endapan dipisah dengan disaring. Filtrat yang diperoleh kemudian dianalisis dengan spektrofotometer UV-vis.

Hasil Penelitian 1. Karakterisasi Humin Humin yang diperoleh dari ekstraksi tanah gambut dalam penelitian ini di karakterisasi menggunakan spektroskopi inframerah, penentuan kadar abuserta penentuan kuantitatif gugus fungsional humin. Dari hasill karakterisasi humin dengan menggunakan spektroskopi inframerah secara kualitatif dapat memberikan memberikan hasil seperti Gambar 1.

11

( Vb-Vs ) x N x 105 cmol/kg


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kemudian akan berinteraksi dengan H+sehingga terbentuk gugus –COOH setelah humin dicuci dengan asam (HCl/HF). Proses pelepasan logam logam dan terbentuknya gugus –COOH diindikasikan dengan hilangnya serapan pada panjang gelombang 1382,9 cm-1 dan 1377,1 cm1 serta munculnya serapan pada panjang gelombang 1705 cm-1 yang merupakan serapan panjang gelombang dari gugus –COOH. Keberhasilan proses pencucian HCl/HF selain dapat dideteksi dengan data spektra IR seperti telah dibahas sebelumnya, juga dapat diketahui dari perubahan kadar abu, hal ini disebabkan karena kadar abu berkaitan erat dengan kandungan mineral. Makin tinggi kandungan mineral, maka makin tinggi kadar abu. Hasil penetapan kadar abu dari humin tanpa pencucian dan dengan pencucian HF/HCl di tunjukkan pada Tabel 2. Gambar 1. Spektra inframerah humin (a) dengan pencucian dan (b) tanpa pencucian HCl/HF

Tabel 2. Kadar abu humin tanpa pencucian dan dengan pencucian HCl/HF

Tabel 1. Panjang gelombang inframerah humin setelah pencucian dan sebelum pencucian dengan HCl/HF

Gugus -OH -C-H alifatik

Panjang gelombang (cm-1) Sebelum Setelah Pencucian Pencucian 3425,3 3425,3 2920

2850,6

Tahap Pencucian

Kadar abu (%, b/b)

Tanpa pencucian

10,01

Pencucian dengan akuades

4,36

Pencucian dengan HF/HCl 3x

1,26

1037,6

-Si-O -

-COO

Pada Tabel 3 disajikan komposisi kuantitatif gugus fungsional pada humin hasil isolasi yang dilakukan dengan menggunakan metode titrasi potensiometri. Data ini diperlukan untuk mengetahui seberapa banyak gugus fungsional yang ada pada humin terutama gugus –COOH dan –OH fenolat yang dapat berfungsi sebagai situs aktif adsorpsi logam.

1382,9

1705 -C=O dari –COOH + Pengaruh Na , Mg2+, Ca2+ pada 1377,1 COOSpektra infra merah humin sebelum pencucian dan setelah pencucian dengan HCl/HF memperlihatkan perbedaan spektra yang cukup signifikan seperti yang terlihat pada Tabel 1. Proses pencucian dengan menggunakan larutan asam (HCl/HF) dapat menyebabkan lepasnya logam-logam yang berinteraksi dengan gugus – COO-pada humin, hal ini terjadi karena ikatan antara logam dengan ion F- maupun Cl- lebih kuat dari pada ikatan antara logam dengan gugus – COO-. Gugus –COO- akibat lepasnya logam

Tabel 3. Perbandingan kandungan keasaman total, gugus karboksilat, dan gugus hidroksi fenolat humin Kandungan Gugus Fungsional dalam humin(cmol/Kg)

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Hasil Penelitian

sehingga terbentuk gugus–COOHdan –OH pada eosin. Gugus –COOH dan–OH dari eosin akan berinteraksi dengan gugus –COO- dari humin pada pH sekitar 3 – 5 karena gugus karboksil dari humin terdisosiasi dan melepaskan protonnya pada pH sekitar 3,0 menjadi ion karboksil sehingga menghasilkan senyawa humin yang bermuatan negatif.

Hasil Penelitian Saleh

ini (2004) Gugus (-COOH)

210,0

199

Gugus –OH fenolat

343,5

344

Setelah pH 4, peningkatan pH akan menyebabkan berkurangnya H+ dalam larutan. Sehingga dengan naiknya pH akan menyebabkan terjadinya penurunan jumlah eosin yang teradsorp. Penurunan jumlah eosin yang teradsorp juga disebabkan karena pada kondisi basa akan terbentuk ion OH- dan pada pH sekitar 9,0 gugus hidroksi fenolik pada humin juga mulai terdissosiasi dan menghasilkan senyawa bermuatan negatif yang besar. Adanya dissosiasi dari gugus hidroksi fenolik semakin membuat eosin sulit teradsorp sehingga pada penelitian ini adsorpsi optimum eosin terjadi pada pH 4. Pada Gambar 3 terlihat bagaimana gugus -COO-dan – O- dapat terjadi pada eosin.

2. Interaksi Humin dengan Eosin Pengaruh variasi pH terhadap eosin oleh humin

C teradsop (mg/mL)

Dari grafik hubungan pH dengan konsentrasi eosin teradsorp pada Gambar 2 secara umum menunjukkan kecenderungan bahwa dari pH 2 sampai sekitar pH 8 laju adsorpsi eosin cenderung konstan tidak mengalami perubahan yang signifikan.

Br

9 8.5 8 7.5 7 6.5 6 5.5 5 4.5 4

NaO

Br

Br

(Z)

O

O

-

O

Br (Z)

O

O

+ 2Na Br

(Z)

(E)

Br Br

COONa

0

2

4

6

8

10

12

14

pH

(E)

COO

Br

-

Gambar 3.Reaksi pembentukan gugus -COO-dan O- pada eosin

pH

Gambar2. Grafik hubungan konsentrasi eosin teradsorp.

(Z)

Optimasi waktu terhadap eosin

dengan

kontak

adsorpsi

humin

Setelah mengetahui pH optimum adsorpsi maka parameter selanjutnya yang ditentukan adalah waktu kontak optimum antara humin dengan eosin, Konsentrasi awal eosinadalah 10 ppm, volume larutan 25 ml, berat humin 50 mg, dan pH 4. Setelah diinteraksikan antara eosin dan humin maka waktu optimum adsopsi diperoleh saat waktu kontak 60 menit pada interval waktu kontak antara 60 menit sampai 240 menit.Hasil yang di peroleh ini mengindikasikan bahwa setelah 60 menit proses adsorpsi oleh senyawa humin telah mengalami penjenuhan dan mencapai kesetimbangan seperti yang terlihat pada Gambar 4. Hal ini disebabkan karena gugus fungsi yang

Konsentrasi awal eosin 10 ppm, volume larutan 25 ml, berat humin 50 mg, waktu interaksi 120menit. Adsorpsi optimum humin terhadap eosin terjadi pada pH 4.Interaksi yang terjadi pada suasana asam kemungkinan merupakan interaksi yang melibatkan ikatan hidrogen.Hal ini disebabkan karena adanya gugus –COONa dan gugus –ONa dari eosin. Jika proses pelarutan dalam suasana asam dilakukan maka akan menyebabkan lepasnya ion Na+dari masingmasing gugus sehingga terbentuk gugus –COOdan gugus–O-, kemudian gugus –COO-dan gugus –O- akan berikatan dengan H+ pada suasana asam

13

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ada pada bagian permukaan humin telah berinteraksi seluruhnya dengan eosin yang mengakibatkan humin tidak mampu lagi untuk mengikat senyawa eosin.

Dari Gambar 6 diperoleh harga k orde satu = slope, yaitu 8,4x 10-3menit-1, dengan harga kelinearan R2 = 0,9845. Kesimpulan Berdasarkan hasil penelitian yang diperoleh dapat disusun kesimpulan-kesimpulan sebagai berikut :

E osin terad sorp -5 (x10 mol/l)

1,4 1,2 1 0,8

1. Karakterisasi humin dengan menggunakan

0,6

spektroskopis inframerah, menunjukkan bahwa sebelum pencucian dengan HCl/HF terdapat puncak serapan pada angka gelombang sekitar 1382,9 cm-1 yang berasal dari ulur anionik –COO- namun setelah pencucian dengan HCl/HF serapannya semakin lemah. Selain itu muncul puncak serapan baru pada angka gelombang 1705,0 cm-1 yang dihasilkan oleh vibrasi ulur C=O dari gugus –COOH.

0,4 0,2 0 0

50

100

150

200

250

300

Waktu (menit)

Gambar 4. Grafik hubungan waktu adsorpsi dengan jumlah eosin yang teradsorp. Konstanta laju reaksi Dari data optimasi waktu antara humin dengan eosin,besarnya konstanta laju reaksi (k) dapat dihitung dengan membuat kurva ln (Co/Ct)/Ct lawan t/ Ctseperti pada persamaan C ln  A 0  CA CA

2. Dalam penelitian ini diperoleh kandungan –

OH fenolat pada humin sebesar 343,5 cmol/kg yang lebih tinggi dari gugus karboksilat yaitu sebesar 210,0 cmol/kg.

    k . t  K 1 CA

3. Adsorbsi humin terhadap eosin optimum pada

pH 4 dengan waktu kontak optimum 60 menit 4. Konstanta laju reaksi untuk eosin adalah

Konstanta laju reaksi (k) merupakan nilai slope dari kurva tersebut. Plot hubungan antara ln (Co/Ct)/Ct lawan t/ Ctuntuk adsorpsi eosindapat dilihat pada Gambar 5

sebesar 8,4x 10-3menit-1 Pustaka Aiken. G. R., McKnight, D. M., Wershaw, R.L., dan Mac Charty. P, 1985 ”An Introduction to Humic Substances in Soil, Sediment and Water; Geochemistry, Isolations and Characterization”, John Wiley and Sons, New York

Grafik Ln (Co /Ct)/Ct lawan t/Ct

Ln (Co /Ct)/Ct

10000 0000 8000 0000 6000 0000

Anshar, A.M.,Santosa, S.J., dan Sudiono, S., 2014, Kajian Adsorpsi Metilena Biru Pada Humin, Prosiding Seminar Nasional Geofisika, 189-193.

4000 0000

y = 0,0084x + 2E+07 2

2000 0000

R = 0,9685

0

0

1E+09

2E+09 3E+09

4E+09

5E+09

6E+09

7E+09 8E+09

t/Ct

Gaffey, S. J., Marley, N. A., dan Clark, S. B., 1996, Humic and Fulvic Acid and Organic Colloidal Matterial in Environmental ( dalam Gaffney, J. S.,et.al., 1996, Humic and Fulvic Acid ; Isolation, structure and Environmental Role)American Chemical society., Washington

Gambar 5. Grafik hubungan antara ln (Ct/Co)/Ct lawan t/Ct pada adsorpsi metilena biru dengan humin dengan berat eosin 10 mg, konsentrasi awal larutan 10 ppm, volume larutan 25 mL, dan pH 4

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Hamdaoui, O. and Chiha, M., 2006, Removal of Methylene Blue from Aqueous Solutions by Wheat Bran, Acta Chim. 54 : 407–418

Pemcemaran Air Sungai, Tesis, S2, Universitas Diponegoro, Semarang Razae, A., Ghaneian, M. T., Hashemian, S. J., Mousavvi, G.,Khavanin, A., Ghanizadeh, G., 2008, Decolorization of Reactive Blue 19 Dye From Tekstil Wastewater by the UV/H2O2 Process, Journal of Applied Sciences 8, Asian Network for Scientific Information

Ishiwitari, R., 1985, Goechemistry of Humic Substances in Lake Sediments ( dalam Aiken. G. R., McKnight, D. M., Wershaw, R.L., dan Mac Charty. P, 1985 ”An Introduction to Humic Substances in Soi, Sediment and Water; Geochemistry, Isolations and Characterization”), John Wiley and Sons, New York

Riyani, K., dan Setyaningtyas, T.,Pengaruh Karbon Aktif Terhadap Aktivitas Fotodegradasi Zat Warna Pada Limbah Cair Industri Tekstil Menggunakan Fotokatalis TiO2, Molekul, Vol. 6. No. 2, 113 - 122

Kaled. H,, dan and Fawy H., A., 2011 , Effect of Different Levels of Humic Acids on the Nutrient Content, Plant Growth, and Soil Properties under Conditions of Salinity, Soil & Water Res., 6, (1): 21–29

Saleh, N., 2004, Studi Interaksi antara Humin dengan Cu(II) dan Cr(II) dalam Medium Air, Tesis S2, Universitas gadjah Mada, Yogyakarta

Lawakka, I. 2005, Adsorpsi Merah Reaktif-1 Oleh Karbon Aktif Tempurung Kenari Sebagai Fungsi Waktu dan Jumlah Adsorben, skripsi tidak diterbitkan, Jurusan Kimia, FMIPA, Universitas Hasanuddin, Makassar.

Stevenson, F. J., 1994, Humus Chemistry, Genesis,Composition, Reactions, John Wiley and Sons, New York

Tanasale, M.F.J.D.P., Killay, A., dan Laratmase, M.S.,2012, Kitosan dari Limbah Kulit Kepiting Rajungan(Portunus sanginolentus L.) sebagai Adsorben Zat Warna Biru Metilena, Jurnal Natur Indonesia, 14(2), 165-171

Mahatmanti, F. W., dan Sumarni, W.,2003, Kajian Termodinamika Penyerapan Zat Warna Indikator Metil Oranye (MO) Dalam Larutan Air Oleh Adsorben Kitosan, JSKA.Vol.VI.No.2. Marlena, B., Mukimin, A., Susanti, E., 2012, Dekolorisasi Pewarna Reaktif Pada Air Limbah Industri Tekstil Secara Elektrokimia, Jurnal Riset Teknologi Pencegahan Pencemaran Industri, Vol.2(2). Muna, N., 2014, Adsopsi Zat Warna Melacite Green (MG) oleh Komposit Kitosan Bentonit, Skripsi, Jurusan Kimia, Fakultas Sains dan Teknologi, Universitas Islam Negeri Sunan Kalijaga, Yogyakarta Prasetyo. A.E., Kurniawan.I.,Hartono. S.B., Ismadji.S., 2005, Adsorpsi Zat Warna Dari Limbah Cair Sintetis DenganMenggunakan Lumpur Aktif, prosiding, The 4thNational Conference: Design and Application of Technology Rahmayati, D., 2011, Pengaruh Kegiatan Industri Terhadap Kualitas air sungai Diwak Di Bergas Kabupaten Semarang dan Upaya Pengendalian

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BIOSORPTIONOF Cd(II) ION BYDRAGONFRUITPEEL (Hylocereus polyrhizus) A. M. Tanasal1*, N. La Nafie2, P. Taba2 Department of Chemistry, Faculty of Mathematics and Natural Sciences, State University of Hasanuddin, Makassar, South Sulawesi90425 E-mail: [email protected]

Abstrak. Kulit buah naga merupakan material yang melimpah dan murah. Material ini telah digunakan sebagai adsorben dalam proses biosorpsi untuk penghilangan ion logam Cd(II) dari limbah cair. Biosorpsi ion logam Cd(II) oleh kulit buah naga dilakukan pada variasi waktu kontak, pH dan konsentrasi. Konsentrasi ion logam Cd(II) sebelum dan setelah adsorpsi ditentukan dengan menggunakan Spektrofotometer Serapan Atom (SSA). Hasil penelitian menunjukkan bahwa waktu optimum yang diperoleh adalah 20 menit dan pH optimum adalah 5. Kapasitas adsorpsi ion Cd(II) oleh kulit buah naga ditentukan dengan menggunakan isotermal adsorpsi Langmuir dan Freundlich. Dari hasil penelitian ini diperoleh bahwa biosorpsi ion logam Cd(II) dengan menggunakan kulit buah naga sesuai dengan model isotermal Langmuir dengan nilai kapasitas biosorpsi (Qo) yakni sebesar 36,50mg/g. Gugus fungsi yang terlibat dalam biosorpsi ion logam Cd(II) oleh kulit buah naga adalah gugus hidroksil (-OH). Kata kunci: biosorpsi: Cd(II), isotermal adsorpsi, kulit buah naga, SSA. Abstract. Dragon fruit peel is a material that is abundant and cheap. The material has been used as an adsorbent in the biosorption process for the removal of metal ions of Cd(II) from wastewater. Biosorptionof Cd(II) ion bydragonfruitpeel was doneon the variationof contact time, pHandconcentration. The concentration ofmetal ionsCd(II) beforeandafteradsorptionwas determined usingAtomic Absorption Spectrophotometer(AAS). Results showed that the optimum time was 20 minutes and the optimum pH was 5. Adsorption capacity was studied by both isotherm adsorptions of Langmuir and Freundlich. Results showed that the biosorption of Cd(II) ion using dragon fruit peel fullfilled the isotherm Langmuir model with the biosorption capacity (Qo) of 36,50 mg/g. The functional group involved in metal ion biosorption of Cd(II) by the peel of dragon fruit is a hydroxyl group (-OH). Keywords: biosorption, Cd(II), adsorption isotherm, dragonfruitpeel, AAS.

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products generated. The problem of water pollution by heavy metals represents a challenge and biosorption can be a solution of this problem (Viera dan Volesky, 2000). Biosorption is one of alternative techniques for waste treatment, that is taking metals by biological materials or biosorbent from the solution. This method is competitive, cheap and effective (Volesky, 2001).Biosorbent available abundance both naturally and as a product or waste industrial activity, has a high adsorption capacity, and allow it to be renewed(Bailey et al., 1999). Some product of industrial and agricultural activities result has the potential to be used as an inexpensive adsorbent. Green coconut shell powder (Cocos nucifera) potentially removing Cd (II)ions (Widihati et al., 2010). Rice straw powder can attract ions of heavy metals such as Cd (II) from polluted waters (Fatoni et al., 2010). Moringa seed powder can be used to reduce measure of cadmium in water(Umar dan Liong, 2014). Saikaew dan Kaewsarn (2010) using durian peel as biosorbent cadmium ions. La Nafie et al. (2012) utilizes red meranti wood powder as biosorbent cadmium ions. Previous research has also been done using dragon fruit peel as biosorbent metal ions Mn(II) (Priyantha et al., 2013), Pb(II) dan Ni(II) (Mallampati, 2013). One of agricultural waste utilization which still lacking is dragon fruit peel. Dragon fruit peel is a source of organic matter and the results of the analysis showed that the material

INTRODUCTION Environmental pollution is now increasing rapidly, mainly due to industrial activities. This is caused by industrial waste containing heavy metals from a variety of chemicals that are very harmful and toxic for living beings even in low concentrations (Achmad, 2004). Cadmium (Cd) is one of the heavy metals that contaminate aquatic environments as a result of the disposal of industrial waste and mining waste. Cadmium is widely used in metal plating process is a heavy metal that is dangerous because it can cause high blood pressure, kidney damage, testicular tissue damage and destruction of red blood cells (Achmad, 2004).Pollution caused by cadmium has a negative impact on ecosystems and human life, such as cases of poisoning due to contamination of water by Cd metal happening around Toyama city Jinzu river island Honsyu Japan in 1960. Patients experiencing softening entire body skeleton followed by death due to kidney failure. The disease is known as Itai-itai Disease (Wardhana, 2001). Efforts to combat environmental pollution previously have been carried out. Deposition method, oxidation-reduction, ion exchange, filtration, evaporation, reverse osmosis, and solvent extraction is a common method used to remove metal ions from waste. However, this method has drawbacks such as metal fastening is not perfect, the amount of chemicals and energy is also needed, as well as sludge and toxic waste 17


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contains lignin, hemicellulose, cellulose, carbohydrates, proteins and other phenolic compounds in which there are nitrogen, carbon, hydrogen, and sulfur. All of these contain a hydroxyl and carboxyl that can binding pollutants in this case is a metal ion (Mallampati, 2013). Based on the above argument it is necessary to investigate the ability of dragon fruit peel powder(Hylocereus polyrhizus) are known to contain cellulose, pectin and lignin in adsorbing heavy metals, especially the heavy metal cadmium (Cd) and the optimum condition adsorption cadmium (Cd) ions metal.

Procedure Preparation biosorbent dragon fruit peel(Hylocereus polyrhizus) Dragon fruit peel is washed with running water to remove dirt, rinsed with aquabidestand drained. Dragon fruit peel then cut into small pieces and dried in the sun for 7 days. After that dragon fruit peel is heated at 80 ° C for 24 hours and stored in a desiccator. Afterwards, dragon fruit peel crushed using the crusher, and sieved with a 100 mesh size sieve but did not pass 230 mesh sieve. Dragon fruit peel powder then heated at 80 ° C and stored in a desiccator.

MATERIALS AND METHODS Production the Cd(II) solution Cd(NO3)2.4H2O powder weighed as much as2,7424 gram, then dissolved withHNO3 p.aand diluted with aquabidest until the volume of solution of 1 L. Subsequently standard solution ofCd(II) with a concentration of 1000 mg/L pipette 100 mL and diluted to a volume of solution 1 L to create a standard solution of Cd(II) 100 mg/L.

Materials research Materials used in this study were dragon fruit peel (Hylocereus polyrhizus), Cd(NO3)2.4H2O EMSURE (MERCK), HNO3 (p.a) 65 %, aquades,aquabidest, Whatman 42filter paper, alumunium foil, universal pH paper, and label paper. Instrumentationresearch Tools used in this study are tools glass commonly used, oven SPNISOSFDmodels, magnetic stirrer velp scientificamodels, digital scale Ohaus NO AP210models, sieve(100 mesh dan 230 mesh), cusher, atomic absorption spectrophotometer (AAS)buck scientific205 VGPmodels, desiccator, centrifugeangular 6 selectamodels, ultrasonic and FT-IR spectrophotometer SHIMADZU 8201 PCmodels, pH meter WTW 315imodels.

Determination of optimum time biosorption Cd(II) ion bydragon fruit peel powder(Hylocereus polyrhizus) Solution of Cd(II) with a concentration of 100 mg/L was prepared. Dragon fruit peel powder was weighed as much 200 mg and put in 50 mL solution of Cd(II). The mixture is shaken with a magnetic stirrer for 5 minutes, centrifuged and filtered with Whatman 42 filter paper. Absorbance of the filtrate was 18


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measured by AAS at a wavelength maximum 228.8 nm. Then repeated the experiment with a time of 10; 15; 20; 30; 40; 50; 60; 70; 80 and 90 minutes. Each experiment was

performed two repetitions. Blank experiments performed as above but without shaking with a magnetic stirrer. was performed two repetitions. Blank experiments performed as above but without shaking with a magnetic stirrer.

Determination of optimum pH biosorption of Cd(II) ion by dragon fruit peel powder(Hylocereus polyrhizus) Many as 200 mg of powdered dragon fruit peel put in 50 mL solution of Cd(II) with a concentration of 100 mg/L and pH 2. The mixture was then shaken for optimum time 20 minutes, centrifuged and filtered with Whatman 42 filter paper. The absorbance of the filtrate is measured by AAS. The above experiment was repeated with variations in pH 3, 4, 5, 6 and 7. Each experiment was performed two repetitions. Blank experiments performed as above but without shaking with a magnetic stirrer. The optimum pH is pH where the concentration of adsorbed (Cadsorption) the largest.

FT-IR analysis FT-IR (Fourier Transform Infra Red) spectrum analysis carried out for dragon fruit peel before and after adsorption at FT-IR spectrophotometer SHIMADZU 8201 PC models. Spectra were recorded, the wave number region 4000-340 cm-1with a resolution of 1 cm-1at room temperature with a detector DTGS (Deuterated Triglycine Sulphate). Samples crushed along KBr with a mass ratio of KBr and sample is 1:10. The mixture was then put in a special place that is round and then pressed for 10 minutes at a pressure of 72 Torr (8 to 20 tons per unit area) to produce a very thin circle. Observations on IR spectra is performed to determine changes in the functional groups that occur before and after the process adsorption of Cd(II) by biomass dragon fruit peel.

Determination capacity biosorption of Cd(II) ion by dragon fruit peel powder(Hylocereus polyrhizus) Dragon fruit peel powder was weighed as much as 200 mg and put in 50 mL solution of Cd(II) with a concentration of 50; 100; 150; 250; and 400 mg/L. The mixture shaken for optimum time 20 minute at optimum pH 5, centrifuged and filtered with Whatman 42 filter paper. The absorbance of each filtrate was measured by SSA. Each experiment

RESULTS AND DISCUSSION Optimum time biosorption Cd(II) ion by dragon fruit peel powder (Hylocereus polyrhizus) Data amount of metal ions Cd(II) adsorbed by dragon fruit peel at different contact time is shown in Figure 1. 19


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Total Cd(II) ion adsorbed (qe, mg/L)

Figure 1 shows that the adsorption of Cd(II) by dragon fruit peel increases with shaking time. But to a certain extent the addition shaking time does not affect significantly the amount of ions Cd(II) which is absorbed by dragon fruit peel powder. Adsorption of Cd(II) an increase of shaking time 5 minutes to 20 minutes. It can be seen from the increase in the amount of ions Cd(II) adsorbed in the 5th minute as much as 10.68 mg/g to 11.36 mg/g in the 20th minute. However, after the 20th

minute amount of ion Cd(II) adsorbed decreased relatively small. The relatively small amount of decrease indicates that the active site on the surface of the dragon fruit peel adsorbent has been saturated with ions Cd(II).

12.0 10.0 8.0 6.0 4.0 2.0 0.0 0

20

40

60

80

100

Time (minute)

Figure 1. Relationship between contact time (minutes) with the amount of Cd(II) ion adsorbed (mg/g) by the dragon fruit peel powder (pH 5, the initial concentration of Cd(II) ion = 100 ppm). time for absorption of ion Cd(II) by According Saikaew and using the sago pulp is 20 minutes. Kaewsarn (2010) removal of metal Based on data from this study, the ions Cd(II) from wastewater by using optimum time of adsorption ofCd(II) durian peel powder need adsorption by dragon fruit peel is 20 minutes. time during 15 minutes. Nailufar Time was then used to determine the (2010) reported that the optimum pH optimum and maximum capacity contact time for the adsorption of of adsorption of Cd(II) by dragon fruit Cd(II) by using the tofu pulp is 20 peel. minutes. It is also reported by Pabiban (2009) in which the optimum contact 20


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OptimumpHbiosorptionof Cd(II) ionbydragon fruit peel powder(Hylocereus polyrhizus) One of the most important factors in adsorption besides time is pH. The optimum pH biosorption of Cd(II) ion by dragon fruit peel is

determined by counting the amount of Cd(II) ions adsorbed (qe) as a function of pH. To determine the optimum pH in this study used a pH of 2-7. Effect of pH changes in ion biosorption of Cd(II) by dragon fruit peel powder can be seen in Figure 2.

14 12 10 8 6 4 2 0 0

2

4

6

8

pH

Figure 2. Relationship between the pH of the amount of Cd(II) ion adsorbed (mg/g) by dragon fruit peel powder (optimum time is 20 minutes, concentration of Cd(II) ion = 100 ppm). adsorbed decreased. Decrease the The higher the pH the higher the amount of metal ions adsorbed on the amount of Cd(II) ions which is adsorption process at high pH occurred absorbed by dragon fruit peel powder. before reaching a pH where the metal But after passing an optimum pH, the ions precipitate caused by the amount of ions Cd(II) which formation of hydroxyl complexes of isabsorbed by dragon fruit peel powder metal ions dissolved so that the metal began to decline. ion can not bind to the active groups At low pH (2), the amount of on the adsorbent(Ahmad, et al., 2009). Cd(II) ions which is absorbed very Cd(II) ion precipitated at pH 8.5 to 9 small at 1.18 mg/g. This is because at (Hawari dan Mulligan, 2006). + low pH H ion compete with the metal Based on Figure 2, the pH cation Cd2+ to bind at active groups on optimum adsorption of Cd(II) ion by the adsorbent (Ahmad, et al., 2009). At the dragon fruit peel powder is at pH pH 3-5 an increase in the amount of 5. This is also supported by previous Cd(II) ion which is absorbed by studies that get the same results by dragon fruit peel powder, which the using durian peel (Durio zibethinus) absorption of Cd(II) ion by the largest (Saikaew dan Kaewsarn, 2010), Rice dragon fruit peel powder occurred at Straw (Fatoni, et al., 2010), Red pH 5 in the amount of 12.47 mg/g. Meranti Wood powder(Shorea Then at pH 6 the amount of Cd(II) ion Pamifotia Dyer) (La Nafie, et al., 21


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2012), and the sagopulp (Pabiban, 2009) as an adsorbent for the adsorption of Cd(II) ion. The addition of acid on biosorption process allows the hydrolysis of cellulose and lignin that can break down the molecules that make available many -OH groups which can bind to Cd(II) ion. This is what might cause the optimum biosorption process occurs at a slightly acidic pH ie at pH 5.

dragon fruit peel powder as a function of ion concentration of Cd(II) ion in Figure 3. The bigger concentration of Cd(II) ion in solution, the more bigger the amount of Cd(II) ion can be absorbed by dragon fruit peel powder. Figure 3 shows that the adsorbent saturation has not been achieved, so the two models adsorption isotherm (isothermal Langmuir and Freundlich) is used. Graph showing the relationship between concentration of Cd(II) ion after adsorption (Ce) vs adsorption capacity (Ce/qe) was prepared according to the Langmuir adsorption models as shown in Figure 4 and the concentration of Cd(II) ion after adsorption(log Ce) vs adsorption capacity (log qe) was prepared according to Freundlich adsorption models as shown in Figure 5.

Biosorption capacity of Cd(II) ion by dragon fruit peel powder(Hylocereus polyrhizus). Concentration also affect the adsorption. The higher the concentration of a solute, the more the solutes which can be adsorbed by an adsorbent. It can be seen from the amount of Cd(II) ion adsorbed by


30 25 20 15 10 5 0 0

100

200

300

400

500

Concentration (ppm)

Figure 3. The relationship between concentration of Cd(II) ion (mg/L) by the amount of Cd(II) ion adsorbed (mg/g) by the dragon fruit peel powder at the optimum time 20 minutes and at optimum pH 5.

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14 12

y = 0.0274x + 2.9753 R² = 0.9913

Ce/qe

10 8 6 4 2 0 0

100

200

300

400

Ce (mg/L)

Log qe

Figure 4. Curve Langmuir isotherm for adsorption of Cd(II) ion by dragon fruit peel powder 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0

y = 0.5041x + 0.199 R² = 0.9889

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Log Ce

Figure 5. Curve Freundlich isotherm for adsorption of Cd(II) ion by dragon fruit peel powder dragon fruit peel is Langmuir Figures 4 and 5 show that the isotherm, where in the adsorbent and adsorption is more in line with the adsorbate form a single layer adsorption of Cd(II) by dragon fruit (monolayer). peel powder is Langmuir isotherm Based on previous studies that compared with the Freundlich reported by Nailufar (2010) on the isotherm models. This can be seen adsorption of Cd(II) ion by using the from the Langmuir isotherm equation tofu pulp, the adsorption capacity Qois 2 R value is0,9913while the Freundlich equal to 17,06 mg/g and Pabiban isotherm equation is 0,9889. Based on (2009) eported the adsorption of Cd(II) the Langmuir isotherm using the sago pulp value Qo= 11,79 valueQo(adsorption capacity) was mg/g. While the adsorption of Cd(II) obtained by36,50 mg/g or 0,32 ion by durian peel got valueQo= 18,55 mmol/g. According toPriyantha et al. mg/g (Saikaew dan Kaewsarn, (2013) isothermal more in line with 2010).This shows that the skin of the 23


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dragon fruit is more effective in adsorbing Cd(II) ion compared to pulp, pulp sago, and durian peel.

groups are functional groups involved in biosorption of Cd(II) ion by dragon fruit peel powder. To form complexes, empty orbital on 5s2experience hybridization provides 4 orbital is 5s and 5p, which is then filled by four pairs of electrons originating from the hydroxyl group(–OH) as a ligand. The bond that is formed is a covalent coordination bond because of the FTIR spectrum peaks (–OH) is not lost but only shifted, so that it can be concluded that the bond formed between groups(–OH)and Cd(II) ion is a covalent coordination bond. Then shift wave numbers become bigger, showing stronger bonding happens. Seeing the results of FT-IR in Figure 6, it is predicted that there is a bond between the hydroxyl functional groups (–OH) derived from lignin and cellulose with Cd(II) ion due to the hydroxyl group (–OH) on cellulose and lignin that are not stunted by steric effect while hydroxyl group of pectin stunted by steric effects and also groups (–OH) on pectin derived from the group (–COOH), oxygen in the group (–OH) and the group (–CO) has the same ability to withdraw electrons due to the effect of conjugation so possibility that shift is a group (–CO).

FT-IR analysis results Biosorbent dragon fruit peel was analyzed by FT-IR to determine the binding functional group Cd(II) ion. FT-IR analysis is done by looking at the change of the IR spectra before and after biosorption of Cd(II) ion by dragon fruit peel shown in Figure 6. Figure 6a shows a peak at wavenumber 1056,99 cm-1 (stretching C-O), 1643,35 cm-1 (stretching C=O), 2922,16 cm-1 (aliphaticC-H stretching), dan 3415,93 cm-1 (stretching–OH). The same peaks are also seen in the figure 6b, except peak at 3415,93 cm-1 (stretching –OH) shifted into 3441,01 cm-1. This shift shows the interaction between the Cd(II) ion with the hydroxyl functional groups (–OH) contained in the skin of dragon fruit. This is reinforced by the shift in wave numbers 761,88 cm-1and 524,64 cm-1respectively into771,53 cm-1 dan 536,21 cm-1. Uptake was found between500and700cm-1is derived from the uptake of bond between ions metal M and O are replaced with Cd(II) form a Cd-O bond (Jethva, 2015).This functional

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a

2922.16

761.88

125

50

771.53

1056.99

1643.35

2922.16

3415.93

75

0

4250

4000

3750

3500

1645.28

1058.92

25

3441.01

% Transmitan

b

536.21

524.64

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3250

3000

2750

2500

2250

2000

1750

1500

1250

-1

Bilangan Gelombang (cm )

a

25stunted by steric effects Figure 7. Hydroxyl Group (–OH) is

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totalenergy=74.029 kcal/mol

1 2

Figure 8. Hydroxyl group (–OH) is not stunted by steric effects H O

OH H H

OH H O

CH2

H

H O

CH2OH O H H OH

OH H3CO H

H

OH

2

OH

O

HO

OCH3 OH1

OH

Cd2+

OH

OH OCH3

OH

OH

O H OCH3

HO

OH H H

OH H

O CH2OH

CH2 H

H O

O H OH

H

H

OH

O H

Figure 9. Forms of bonding that occurred between Cd(II) ion with cellulose and lignin 26


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Figures 7 and 8 show the difference in bond energies on the hydroxyl group (–OH)1is stunted by steric effect and (–OH)2is not stunted steric effects in the structure of lignin. The bond energy difference indicates that the group tends to bind Cd(II) ion is a group (–OH)2is not stunted by steric effects. Group (–OH)2is smaller binding energy tends to be more stable and its structure group (–OH)2more freer than the group (–OH)1which stunted by steric effects. The proposed bond forms given in Figure 9.

Sorbents for Heavy Metals, Water Res., 33(11), 2469-2479. 4. Fatoni, A., Hindryawati, N., and Sari, N., 2010, Pengaruh pH Terhadap Adsorpsi Ion Logam Kadmium(II) oleh Adsorben Jerami Padi, J. Kimia Mulawarman, 7(5), 59-61. 5. Hawari, A.H., and Mulligan, C.N., 2006, Biosorption of Lead(II), Cadmium(II), Copper(II), and Nickel(II) by Anaerobic Granular Biomass, Bioresour. Technol.,97, 692-700. 6. Jethva, H.O., 2015, FTIR Spectroscopic and XRD Analysis of Gel-Grown, Cadmium LevoTartrate Crystals, IJAR, 1(4), 1-3. 7. La Nafie, N., Zakir, M., and Karoma, M.J., 2012, Pemanfaatan Serbuk Kayu Meranti Merah (Shorea parvifolia) Sebagat Biosorben Ion Logam Cd(II), Indo. Chim. Acta, 5(2), 32-40. 8. Mallampati, R., 2013, Biomimetic Synthesis Of Hybrid Materials For Potential Applications, A Thesis unpublished, Department Of Chemistry National University Of Singapore, Singapore. 9. Nailufar, A.A., 2010, Biosorpsi Ion Cd(II) oleh Ampas Tahu, Skripsi tidak diterbitkan, Jurusan Kimia, Fakultas Matematika dan Ilmu Pengetahuan Alam, Universitas Hasanuddin. 10. Pabiban, D., 2009, Biosorpsi Ion Cd(II) oleh Ampas Sagu, Skripsi tidak diterbitkan, Jurusan Kimia, Fakultas Matematika dan Ilmu Pengetahuan Alam, Universitas Hasanuddin.

CONCLUSIONS Contact time and pH optimum biosorption of Cd(II) ion by dragon fruit peel powder is 20 minutes and pH 5. Biosorption of dragon fruit skin towards Cd(II) ion is in accordance with the Langmuir isotherm with Qo(adsorption capacity) of 36,50 mg/g or 0,32 mmol/g. Functional group involved in ion biosorption of Cd (II) by dragon fruit peel is a hydroxyl group (-OH). REFERENCES 1. Achmad, R., 2004, Kimia Lingkungan, ANDI Yogyakarta, Yogyakarta. 2. Ahmad, A., Rafatullal, M., Sulaiman, O., Ibrahim, M.H., Chii, Y.Y., and Siddique, B.M., 2009, Removal of Cu(II) and Pb(II) ions from aqueous solutions by adsorption on sawdust of Meranti wood, Desalination, 250, 300-310. 3. Bailey, S.E., Olin, T.J., Bricka, R.M., and Adrian, D.D., 1999, A Review of Potentially Low-Cost 27


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11. Priyantha, N., Lim, L.B.L., Dahri, M.K.,and Tennakoon, D.T.B., 2013, Dragon Fruit Skin As a Potential Low-Cost Biosorbent For The Removal of Manganese(II) Ions, JASES, 8(3), 179-188. 12. Saikaew, M., and Kaewsarn, P., 2010, Durian Peels As Biosorbent For Removal Of Cadmium Ions From Aqueous Solution, J. Environ. Res., 32(1), 17-30. 13. Umar, M. R., and Liong, S., 2014, Efektifitas Serbuk Biji Kelor Moringa Oleifera Lamk.Dalam Menurunkan Kadar Kadmium (Cd) Pada Air, J. Alam dan Lingkungan, 5(8), 37-42. 14. Viera, R.H.S.F., and Volesky, B., 2000, Biosorption; a solution to pollution, Int. Microbiol, 3, 17-24. 15. Volesky, B., 2001, Detoxiﬁciation of metal-bearing eﬄuents. Biosorption for the next centry, Hydrometallurgy, 59(2), 203–216. 16. Widihati, I.A.G., Ratnayani, O., and Angelina, Y., 2010, Karakterisasi Keasaman dan Luas Permukaan Tempurung Kelapa Hijau (Cocos Nucifera) dan Pemanfaatannya Sebagai Biosorben Ion Cd2+, J. Kimia, 4(1), 7-14.

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UTILIZATION OF CACAO FRUIT PEEL (Theobroma cacao) AS A BIOSORBENT OF Ni(II) IONS METAL M. Malimongan 1*, N. La Nafie2, P. Taba3 Department of Chemistry Faculty of Mathematics and Natural Sciences Hasanuddin University Makassar 90245

Abstrak. Nikel merupakan salah satu logam berat yang sangat berbahaya karena bersifat karsinogenik dan menyebabkan berbagai penyakit akut dan kronik. Biosorpsi merupakan salah satu metode altenatif untuk menghilangkan keberadaan logam berat dari lingkungan dengan menggunakan biomaterial yang disebut biosorben. Penelitian biosorpsi ion Ni(II) dengan menggunakan kulit buah coklat (Theobroma cacao) dengan variasi waktu kontak, pH, dan konsentrasi telah diteliti. Konsentrasi ion Ni(II) sebelum dan setelah biosorpsi ditentukan dengan menggunakan Spektrofotometer Serapan Atom (SSA). Hasil penelitian menunjukkan bahwa kulit buah coklat (Theobroma cacao) mampu mengadsorpsi ion Ni(II) dan adsorpsi optimum terjadi pada waktu kontak 10 menit dan pada pH 5. Model Isotermal Langmuir dan Freundlich digunakan untuk mempelajari isotermal adsorpsi. Biosorpsi ion Ni(II) oleh kulit buah coklat (Theobroma cacao) lebih sesuai isotermal Langmuir dengan kapasitas biosorpsi 0,21 mmol/g. Gugus fungsi yang terlibat dalam biosorpsi ion Ni(II) oleh kulit buah coklat (Theobroma cacao) adalah gugus –OH dan N-H. Kata kunci: biosorpsi; isotermal adsorpsi; Ni(II); kulit buah coklat; SSA. Abstract. Nickel is one of the heavy metals which is very dangerous because it is carcinogenic and can cause a variety of acute and chronic diseases. Biosorption is one alternative method for the removal of heavy metals from the environment using a biomaterial called biosorbent. Biosorption of Ni(II) ion using cacao fruit peel (Theobroma cacao) with variation of contact time, pH and concentration has been investigated. The concentration of Ni(II) ion before and after adsorption was determined by Atomic Absorption Spectrophotometer (AAS). The result showed that cacao fruit peel (Theobroma cacao) was able to adsorb Ni(II) ion and the optimum biosorption occured at a contact time of 10 minutes and at a pH of 5. Langmuir and Freundlich isotherm models were used to study the adsorption isotherm. Biosorption of Ni(II) ion by cacao fruit peel (Theobroma cacao) fulfilled the Langmuir isotherm with a biosorption capacity of 0,21 mmol/g. The functional groups involved in the biosorption of Ni(II) ion by cacao fruit peel (Theobroma cacao) are –OH and N-H. Key Words : biosorption; adsorption isothermal; Ni(II); cacao fruit peel; AAS.

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Some of biomaterial that is potentially as absorbent of heavy metals is generally derived from agricultural waste. According Sulistyawati 2008, corn cobs contain cellulose which can be used as adsorbents of heavy metals Pb (II). Pectin from citrus fruit peels can be used as adsorbent copper metal ion (Ina et al., 2013). Jengkol skin can be used as absorbent metal ions Cd (II) and Zn (II) (Isnaini et al., 2013). Mangrove bark is used as an absorber ion Cu (II) and Ni (II) (Rozaini et al., 2010). Activated charcoal leather brown fruit (Theobroma cacao l.) Serves as an adsorbent of heavy metals Cd (II) in the solvent water (Masitoh and Sianita, 2013). The results of these studies indicate that agricultural wastes containing functional groups can be further processed as an adsorbent that can be used to absorb heavy metals from waters. Cacao (Theobroma cacao) is one crop that produces waste in the form of skin with large amounts. So far fruit peel in large plantations used as fertilizer or giving nutrients to the plant and as fodder. Cacao fruit peel weighing up to 75% of the entire weight of the fruit, so it can be said that the main waste processing cacao fruit peel. Cacao fruit peel (Theobroma cacao) containing cellulose, pectin, and lignin potentially bind heavy metals such as nickel metal from solution. Based on the previous description of this study is to study the cacao fruit peel (Theobroma cacao) in a bind Ni (II) and determination of functional groups involved in the biosorption process using transfom Fourier infrared (FTIR).

INTRODUCTION This encourages the development of mature technology of rapid development in the sector, industry, transport, households, and even health. Advances in technology could have a negative impact in the form of environmental damage caused by heavy metal waste disposal without first processing (Kusuma, 2014). Heavy metals can not be decomposed by microorganisms and can accumulate in the human body and cause damage to organs (Sembodo, 2006). One of the heavy metals which are environmental pollutants coming from industrial activities are Nickel (Ni) (Aslam et al., 2010). If the concentration of Ni (II) is above the quality standards which when positioned above 0.05 ppm, a variety of acute and chronic diseases can arise in humans such as lung damage and disorders of the kidneys (Borba, et al., 2006). Nickel is carcinogenic and can cause asthma and skin allergies (Aslam et al., 2010). Several technologies have been developed to remove heavy metals in waters such as precipitation, filtration membranes, ion exchange, and coprecipitation. However, these methods have several shortcomings such as metal removal imperfect, expensive equipment, as well as losses caused by the production of a toxic chemical sludge and sewage treatment becomes unsustainable (Isnaini et al., 2013). Biosorption an alternative method to remove heavy metals from the water because it uses materials easily available biomaterial and the cost is relatively low (Alluri et al., 2007). 30



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MATERIALS AND METHODS Materials The materials used in these experiments are cacao fruit peel

(Theobroma cacao), Ni (NO3)2.6H2O EMSURE (Merck), NaOH, HNO3, distilled water, Whatman 42 filter paper, and paper labels.

Apparatus The apparatus used in this study are glass apparatus commonly used in the laboratory, Atomic Absorption Spectrophotometer (AAS) buck scientific VGP 205 models, Ohaus balance NO AP210 models, Crusher, oven, magnetic stirrer Velp scientica, sieve size 90- 100 mesh, stopwatch, desiccator, angular 6 selecta centrifuges, pH meter WTW 315i and FT-IR spectrophotometer Shimadzu prestige 21.

diluted to a volume of 1 L to create a standard solution of 100 ppm. Determination of Optimum Time for the Biosorption of Ni (II) Ions by Cacao Fruit Peel (Theobroma cacao) The Powder of the clean and dried cacao fruit peel (Theobroma cacao) each 0,2 g put into 11 pieces 100 ml Erlenmeyer flask and added 50 mL of Ni (II) ions solution with a concentration of 100 ppm and whipped by using a magnetic stirrer for 5,10, 15, 20, 30, 40, 50 and 60 minutes. Then the mixture is filtered using Whatman 42 filter paper and the absorbance of filtrate analyzed using AAS. All experiments were carried out in duplicate.

Experimental Procedures Preparation of the biosorbent Cacao Fruit Peel (Theobroma cacao) Cacao fruit peel (Theobroma cacao) was obtained from one of the gardens in Tana Toraja.Cacao fruit peel (Theobroma cacao) which has taken further cut into small pieces and washed up with distilled water for several times to remove dirt particles. Cacao fruit peel was then dried in the sun to dry. The clean and dried cacao fruit peel (Theobroma cacao) is put at 80 °C for 24 hours in oven and then stored in a desiccator. The dried cacao fruit peel (Theobroma cacao) is then crushed and sieved using a 100 mesh sieve.

Determination of Optimum pH for the biosorption of Ni(II) Ions by Cacao Fruit peel (Theobroma cacao) The powder of cacao fruit peel (Theobroma cacao) 0,2 g added to 50 mL of Ni (II) ions solution with a concentration of 100 ppm and at a pH of 2. The mixture was stirred for 10 minutes and filtered using whatman 42 filter paper. Absorbance of filtrate analyzed by AAS. The experiment was repeated with each of the different pH 3, 4, 5, 6, and 7. All experiments were carried out in duplicate. The optimum pH is pH where the concentration of adsorbed the largest.

Preparation Stock Ni(II) solution The stock Ni(II) Solution (1000 ppm) were preparated by dissolving 4.9564 g of Ni(NO3)2.6H2O in HNO3 and double distilled water up to a volume of 1 L. Furthermore, the stock solution of Ni (II) 1000 ppm was pipette 100 mL and

Determination of the biosorption capacity of Ni (II) Ions by Cacao Fruit Peel (Theobroma cacao) 31



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The powder of cacao fruit peel (Theobroma cacao) 0,2 g was put into 6 pieces 100 mL erlenmeyer, then added 50 ml of Ni (II) ions solution with a initial concentration was varied from 50, 100, 150, 250, and 400 ppm. The mixture is stirred for 10 minutes and at a pH of 5, then filtered using Whatman 42 filter

paper and the absorbance of filtrate analyzed using AAS All experiments were carried out in duplicate.. Biosorption capacity was calculated using the equation Freunlich or using the Langmuir equation.

FT-IR analysis Biosorbent of cacao fruit peel (Theobroma cacao) before and after being added with a solution of Ni (II) with a pH and a optimum time and dried at a temperature of 80 ° C and then analyzed by FT-IR (Fourier Transform Infra Red) Prestige-21 in the region 4500-340 cm-1 with a resolution of 1 cm-1 at room temperature using DTGS detector (deuterated triglycine sulphate). The sample was crushed with KBr with a mass ratio of 1:10. The mixture was compressed for 10 minutes at a pressure of 72 Torr (8 to 20 tons per unit area) to form a pellet.

10 min which total adsorbed of Ni (II) ions as much as 7.86 mg/g. The optimum time is used for further experimental. The results showed that the adsorption of Ni(II) ions by cacao fruit (Theobroma cacao) increased with the length of time that contact occurs between the adsorbent with adsorbat but at a certain time (optimum time) the total of Ni(II) ions which has adsorbed so that the maximum number of ions Ni(II) are adsorbed not increased. The optimum time biosorption Ni(II) ions in several other studies have shown different results, depending on the type biosorbent used. The optimum time obtained in the study biosorption Ni (II) and Cd (II) ions using rice straw by El-Sayed et al., (2010) is 90 minutes for ion Ni (II). Amaliah et al., (2012) in the study of coral biomass utilization as biosorbent Ni(II) ion also obtain the optimum time of 90 minutes. While the optimum time in the study of adsorption of Ni (II) using palm shell activated carbon by Onundi et al., (2010) is 75 minutes. The optimum time differences of biosorption process depends on compounds contained in biosorbent surface. According to Setiawan et al (2013), the optimum time is the time to reach equilibrium, when biosorbent have functional groups on the metal ion binding to the fullest and after equilibrium is reached bond between the

Results and Discussion Determination of Optimum Time for the Biosorption of Ni(II) Ions by Cacao Fruit Peel (Theobroma cacao) The optimum time biosorption Ni(II) ions by a cacao fruit peel (Theobroma cacao) is determined by calculated the number of Ni(II) ions adsorbed as a function of time. Charts the relationship between the contact time with the number of Ni(II) ions adsorbed by the powder of cacao fruit peel (Theobroma cacao) is shown in Figure 1. Total of Ni(II) ions adsorbed increases from the 5 min to 10 min and become constant even dropped after that. So while, maximum biosorption occur in 32



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Total is adsorp of Ni(II) ions (mg/g)

active groups on the surface of the metal ions biosorbent and weakened so that the desorption process occurs. The interactions between of the functional groups on the surface of the biosorbent of cacao fruit peel and the Ni(II) ions reaches equilibrium at 10 minutes and after equilibrium is reached the adsorbed of Ni(II) ions was dropped because the bond between of the Ni(II) ions and

functional groups on the surface biosorbent weakened and eventually escape back into solution. The time required is relatively fast because the ion Ni (II) adsorbed chemically to form a layer on the surface biosorbent and after coating the surface is covered then no longer able to adsorp of the Ni(II) ions to the maximum.

9 8 7 6 5 4 3 2 1 0 0

10

20

30

40

50

60

70

Time (min) Figure 1. The relationship between of the contact time and the total adsorbed of Ni(II) ions (qe) by cacao fruit peel (pH = 5.1 and Co = 100 ppm) competition between metals and H+ ions that cause the binding of metal ions is reduced. With increasing pH, electrostatic repulsion decreases due to reduction of positive charge density on the sorption sites thus resulting in an enhancement of metal adsorption (Amaliah et al., 2012). Total adsorbed of Ni(II) ion decreased at pH 6-7 because the soluble hydroxyl complexes of Nickel ions is formed (Ahmad et al., 2009). Nickel which are not in the form of ionic is difficult bind to the active groups on the surface of the biosorbent consequently the amount of Ni(II) ions adsorbed is likely to be

Determination of Optimum pH for the biosorption of Ni(II) Ions by Cacao Fruit peel (Theobroma cacao) pH is one of the important factors governing biosorption of metal ions whitout time. Effect of pH change in the biosorption of Ni(II) ion by cacao fruit peel is shown in Figure 2. Figure 2 shows that the total of Ni(II) ions adsorbed is low at low pH values, and increased with increasing pH of the solution up to obtained the optimum pH at pH of 5 which the total absorbed of Ni(II) ions is 5.53 mg/g. The influence of pH can be related with the fact that in an acid environment 33



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Total is adsorp of Ni(II) ions (mg/g)

decreased. The optimum (pH 5) is used to

determine of the capacity biosorption.

6 5 4 3 2 1 0 1

2

3

4

5

6

7

8

pH

Figure 2. The relationship between of the pH and the total adsorbed of Ni(II) ions (qe) by cacao fruit peel (contact time = 10 min and Co = 100 ppm) metal ions solution. Effect of the concentration from the Ni(II) ions in the biosorption process is shown in Figure 3. Graph of relations between qe and Ce in Figure 3 shows that the total adsorbed of Ni(II) ions increases with increasing concentration of the adsorbate.

Total is adsorp of Ni(II) ions (qe mg/g)

Determination of the biosorption capacity of Ni (II) Ions by Cacao Fruit Peel (Theobroma cacao) Total adsorbed (qe) of Ni(II) ion as a function of concentration is determined to calculate of the biosorption capacity. Biosorption capacity is determined by the concentration of the 12 10 8 6 4 2 0 0

100

200

300

400

500

concentration Ce mg/L

Figure 3. The relationship between of the total adsorbed of Ni(II) ions (qe) by cacao fruit peel with concentration (Ce) at the equilibrium (contact time = 10 minutes and pH = 5) 34



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Figure 3 shows that the saturation of the adsorbent has not happened so Langmuir equation and Freundlich equation were used to determine of the

capacity biosorption of Ni(II) ions by cacao fruit peel (Theobroma cacao). The result is shown in Figures 4 and 5.

40 35

Ce/qe

30 25 20

y = 0.080x + 3.087 R² = 0.997

15 10 5 0 0

50

100

150

200 C 250 e

300

350

400

450

Figure 4. Langmuir isotherm using cacao fruit peel (Theobroma cacao)

1.2

log qe

1 0.8 0.6

y = 0.248x + 0.436 R² = 0.913

0.4 0.2 0 0

0.5

1

1.5

2

2.5

3

log Ce

Figure 5. Freundlich isotherm using cacao fruit peel (Theobroma cacao) Figures 4 and 5 show that the Langmuir isotherm is better obeyed than (Theobroma cacao), as is evident from the values of R2 obtained for Langmuir

the Freundlich isotherm by the adsorption isotherm of Ni(II) ions by cacao fruit peel isothermal is 0.997 and for the Freundlich isotherm is 0.913. 35



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Biosorption parameters of Ni(II) ions by cacao fruit peel (Theobroma cacao) which calculated using the

Langmuir isothermal and isothermal Freunlich are shown in Table 1.

Tabel 1. parameters of Ni(II) ions by cacao fruit peel (Theobroma cacao) Langmuir Model Freunlich Model Qo

b

(mmol/g)

(L/mg)

0,21

0,03

R2

K

n

R2

(mmol/g) 0,997

The higher values of regression coefficient (R2) of Langmuir isothermal is indicates the metal ion biosorption process has scope single layer (monolayer) on the cacao fruit peel (Theobroma cacao). In other words, the biosorption of Ni(II) occurs with the functional groups on the surface of the cacao fruit peel (Theobroma cacao) which is considered as monolayer adsorption. Different biosorbent can give different adsorption characteristics, so that the suitability of the adsorption isotherm is very dependent on the type of biosorbent used.

0,05

4,03

0,913

peel (Theobroma cacao) before and after adsorption. Several peaks appearing before the adsorption, such as the wave number 3402.43 cm-1 was assigned of OH group. -OH group supported by CO group from alcohol at the band of 1253.73 cm-1. The band at 1614.42 cm-1 is assigned the NH group from amine, this group is estimated to come from protein of the cacao fruit peel which amplified by the band at 1737.86 cm-1 which is assigned the C = O (peptide bond). After adsorption occurred some shift wave number. This band at 3402.43 cm-1 was shifted to 3419.79 cm-1, which indicated an interaction between the –OH group of the cacao fruit peel biosorbent with the Ni(II) ions. This band at 1614.42 cm-1 shifted to 1625.99 cm-1 which indicate the interaction of the NH group from biosorbent with the Ni(II) ions . This proves that the Ni(II) ion bound to the functional -OH and NH groups. The shift also occurs in the band at 526.57 cm-1 to 514.99 cm-1 assigned to Ni-O bond. And the shifted of the band at 366.48 cm-1 to 376.12 cm-1 assigned to Ni-N bond. It is appropriate of literature that the vibration of metal Ni with O group from the ligand will appear at 600-

Determination of the Functional Groups Involved in Biosorption of Ni(II) Ion by Cacao Fruit peel (Theobroma cacao) The powder of cacao fruit peel before adsorption and after adsorption were analyzed using FTIR. Interaction between of the Ni(II) ion with a cacao fruit peel (Theobroma cacao) is shown on the spectrum of IR spectroscopy. Figure 6 shows the FTIR spectra of cacao fruit 36



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400 cm-1, and vibration of Ni metal bond with group N from the ligand will appear

at 300-390 cm-1 (Triyani et al. , 2013).

2 3 6 2 ,8 0

100

3 4 1 9 ,7 9

4 0 1 ,1 9 3 6 6 ,4 8

5 2 6 ,2 7

6 6 7 ,3 7

4 2 2 ,4 1

3 7 6 ,1 2

6 6 5 ,4 4

5 1 4 ,9 9

8 9 6 ,9 0

1 0 6 0 ,8 5 1 0 5 8 ,9 2

1 3 7 5 ,2 5

1 2 5 3 ,7 3

1 1 0 3 ,2 8

1 2 5 3 ,7 3

1 5 2 3 ,7 6 1 4 4 0 ,8 3

1 6 2 5 ,9 9 1 4 2 7 ,3 2

1 1 0 1 ,3 5

20

1 4 5 0 ,4 7

1 6 2 5 ,9 9

1 7 3 9 ,7 9

2 9 2 9 8 7

3 4 0 2 ,4 3

40

1 6 1 4 ,4 2

2 3 6 2 ,8 0

2 9 2 9 ,8 7

% T ra n s m ita n s

60

1 3 7 7 ,1 7 1 3 1 9 ,3 1

1 7 3 7 ,8 6

8 9 3 ,0 4

80

Serbuk Kulit buah coklat sebelum biosorpsi Serbuk kulit buah coklat setelah biosorpsi

0

4000

3000

2000

1000 -1

Bilangan Gelombang (cm

)

Figure 6. Infrared spectra of cacao fruit peel (Theobroma cacao) before biosorption and after biosorption

Based on the shifted of wave number, it is predicted that the interaction between Ni(II) with a hydroxyl group (OH) of lignin and cellulose and Ni(II) with the NH group of the protein. Forms

of possible interactions between Ni(II) with lignin, cellulose, and protein is shown in Figures 7, and 8.

Figure 7. Forms of interaction between Ni(II) with lignin and cellulose 37



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O HO NH

OH

O

O

N H

H N

HN

O

O H N

O

HO

N H

Ni

H N

2+

OH N H

O

O NH NH

HN

O

O

HN

O

OH O OH

Figure 8. Forms of interaction between Ni(II) with protein Conclusion From the results of the present study, it is be concluded that the optimum time biosorption of Ni(II) ion by cacao fruit peel (Theobroma cacao) is 10 minutes. The optimum pHof biosorption Ni(II) ions by cacao fruit peel (Theobroma cacao) is pH 5. Biosorption of Ni(II) ion by cacao fruit peel (Theobroma cacao) fulfilled the Langmuir isotherm with a biosorption capacity of 0,21 mmol/g. The functional groups involved in the biosorption of Ni(II) ion by cacao fruit peel (Theobroma cacao) are –OH and N-H.

3.

4.

5.

References 1. Ahmad, A., Rafatullah, M., Sulaiman O., Ibrahim, M.H., Chii, Y.Y., dan Siddique, B.M., 2009, Removal Of Cu(Ii) And Pb(II) Ions from Aqueus Solutions by Adsorption on Sawdust of Meranti Wood, Desal, 250, 300310. 2. Alluri, H.K., Ronda, S.R., Settaluri, V.S., Singh, Bondili, J.S., Suryanarayan, V., and Venkateshwar,

6.

38

P., 2007, Biosorption: An Ecofriendly Alternative for Heavy Metal Removal, Afr. J. Biotechnol., 6(25): 2924-2931. Amaliah, R., La Nafie, N., and Fauziah, S., 2012, Pemanfaatan Karang sebagai Biosorben Ion Logam Ni(II), Mar. Chim. Acta., 13(1): 3645. Aslam, M.Z., Shahid, N.R., dan Feroze, N., 2010, Ni(II) Removal By Biosorption Using Ficus Religiosa (Peepal) Leaves, J. Chil. Chem. Soc., 55(1): 81-84. El-Sayed, G.O., Dessouki H.A., and Ibrahim S.S., 2010, Biosorption of Ni (II) and Cd (II) Ions From Aqueous Solutions Onto Rice Straw, Chem. Sci. J., 1-11. Ina A.T., Yulianti, L.I.M., dan Pranata, F.S., 2013, Pemanfaatan Pektin Kulit Buah Jeruk Siam (Citrus nobilis var. microcarpa) Sebagai Adsorben Logam Tembaga (Cu), Skripsi tidak diterbitkan Fakultas Teknobiologi Universitas Atma Jaya, Yogyakarta.



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7. Isnaini, P., Zein, R., dan Munaf, E., 2013, Penyerapan Ion Cd (II) dan Zn (II) dalam Air Limbah Menggunakan Kulit Jengkol (Pithecellobium jiringa Prain), J. Kim. Unand, 2(3): 20-30. 8. Kusuma, I.D.G.D.P., Wiratini N.M., dan Wiratma I.G.L., 2014, Isotermal Adsorpsi Cu2+ oleh Biomassa Rumput Laut, e-Journal Kim. Visvitalis Univ. Pen. Ganesha, 2(1): 1-10. 9. Masitoh, Y.F., dan Sianita, M.M., 2013, Pemanfaatan Arang Aktif Kulit buah Coklat (Theobroma cacao L.) sebagai Biosorben logam berat Cd (II) dalam Pelarut Air, J.Chem., 1(1): 2328. 10. Onundi, Y. B., Mamun, A. A., AlKhatib, M. F., and Ahmed, Y. M., 2010, Adsorption of copper, nickel and lead ions from synthetic semiconductor industrial wastewater by palm shell activated carbon, Int. J. Environ. Sci. Tech., 7 (4): 751-758. 11. Rozaini, C.A., Jain, K., Tan, K.W., Tan, L.S., Azraa, A., and Tong, K.S., 2010, Optimization of Nickel and Copper Ions Removal by Modified Mangrove Barks, Int. J. Chem. Eng. Appl., 1(1): 84-89. 12. Sembodo, B.S.T., 2006, Model Kinetika Langmuir untuk AdsorpsiTimbal pada Abu Sekam Padi, Ekuilibrium, 5(1): 28-33. 13. Setyawan, F.L., Darjito, dan Khunur, M.M., 2013, Pengaruh pH dan Lama Waktu pada Adsorspi Ca2+ Menggunakan Adsorben Kitin Terfosforilasi dari Limbah Cangkang Bekicot (Achatina Fulica), Kim. Student J., 1(2): 201-207. 14. Sulistyawati, 2008, Modifikasi Tongkol Jagung Sebagai Adsorben Logam Berat Pb(II), Skripsi tidak

diterbitkan, Departemen Kimia Fakultas Matematika dan Ilmu Pengetahuan Alam Institut Pertanian Bogor, Bogor. Triyani, N.P., Suhartana, dan Sriatun, 2013, Sintesis dan Karakterisasi Kompleks Ni(II)EDTA dan Ni(II)-Sulfanilamid, Chem Info, 1(1): 354-361.

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Synthesis and Characterization of Nanoporous Carbon from Sugarcanne Bagasse (Saccharum officianarum) with ZnCl2 Activator by Ultrasonic Irradiation as Electrochemical Energy Storage Material Arniati Labanni’, Maming, Muhammad Zakir2 Jurusan Kimia, Fakultas Matematika dan Ilmu Pengetahuan Alam, Universitas Hasanuddin Jl. Perintis Kemerdekaan Km. 10 Makassar 90245 email:[email protected] Abstrak. Penelitian tentang sintesis dan karakterisasi karbon nanopori ampas tebu (Saccharum officianarum) melalui iradiasi ultrasonik dengan aktivator ZnCl2 sebagai bahan penyimpan energi elektrokimia telah dilakukan. Karbon aktif ini merupakan material dasar pembuatan elektroda yang akan dikembangkan menjadi material penyimpan energi elektrokimia. Karbon nanopori dibuat dari bahan ampas tebu, yang melewati 3 tahapan proses yakni karbonisasi pada suhu 350 0C, ekstraksi silika, dan aktivasi dengan ZnCl2 dengan perlakuan iradiasi ultrasonik. Karbon aktif ampas tebu dengan proses iradiasi ultrasonik menunjukkan terjadi peningkatan intensitas yang tajam pada rentang gugus –OH pada bilangan gelombang 3419,79 cm-1. Hasil analisis XRF menunjukkan senyawa dengan kandungan tertinggi daam karbon aktif adalah ZnO sebesar 97,06%, dan hasil analisis XRD menunjukkan karbon aktif memiliki struktur fase amorf dan kristal. Selain itu, hasil SEM menunjukkan pembentukan pori pada karbon aktif dengan iradiasi lebih baik daripada karbon tanpa iradiasi, dengan ukuran pori 1,5 sampai 2 µm. Luas permukaan karbon aktif yang diiradiasi dengan gelombang ultrasonik pada suhu optimum 30 0C selama 60 menit adalah 171,2802 m2/gram dengan nilai kapasitas penyimpanan energi sebesar 0,3284 x 10-5 F/g. Kata kunci: energi elektrokimia, karbon nanopori, ampas tebu, ekstraksi silika, aktivator ZnCl2, iradiasi ultrasonic Abstract. A study on synthesis and characterization of nanoporous carbon derived from sugarcane bagasse (Saccharum officianarum) by ultrasonik irradiation using ZnCl2 activator for electrochemical capasitor application has been investigated. Nanoporous carbon is a basic material for the electrode in the electrochemical energy storage. Nanoporous carbon has been synthesized based on three-steps procedures, i.e. carbonization in temperature of 350 0C, silica extraction, and activation using ZnCl2 with ultrasonic irradiation. Activated carbon with irradiation showed an increasing in intensity of the –OH functional group stretch at wave number of 3419,79. The results of XRF analysis showed the highest content of oxide compound in the activated carbon was ZnO as 97,06%, and result of XRD analysis showed that activated carbon has both amorphous and crystalline. The result of SEM analysis showed that the pores evolvement of irradiated activated carbon was better than un-irradiated activated carbon, with diameter of the pores 1,5 to 2 µm. The surface area of the carbon in optimum temperature of 30 oC for 60 minutes was 171, 2802 m2/g and the energy storage capacity was 0,3284 x 10-5 F/g. Keywords: electrochemical energy storage, nanoporous carbon, sugarcane bagasse, silica extraction, ZnCl2 activator, ultrasonic irradiation

2

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milking of sugar cane, which can be used as starting materials in the manufacture of carbon nanopori application of electrochemical capacitors (Wei, X., Et al., 2011). Activated carbon is made through two stages of carbonization and activation process which is both chemically and physically (Sudibandriyo and Lydia, 2011; Shofa, 2012). Carbonization is the process of burning organic material in the raw materials that cause decomposition of organic material and impurities expenditure and non-carbon compounds. Activation is the process of improvement of the carbonization process. In the carbonization process, carbon adsorption capacity is still low because there is still a residue covering the surface of the pore. In the activation process occurs release of hydrocarbons, tar, and carbon covers inorganic compounds (Aisah, 2010). One of the methods to increase the value of specific capacitance of activated carbon is to use ultrasonic wave irradiation. On ultrasonic waves irradiation occur acoustic cavitation effects which is bubble formation, bubble growth, and bubble solution so that more pores are formed (Suslick, et al., 1996). In this study, activated carbon has been made of bagasse through carbonization, silica extraction, and activation with ultrasonic wave

INTRODUCTION World energy demand is increasing from time to time. But the problem is the source of fossil fuels as the only reliable source of energy that is now diminishing. This leads to a national energy crisis that required of other renewable energy sources. One of them is an electrochemical energy storage. Electrochemical energy is energy derived from chemical processes. Electrochemical energy storage consists of three types of system as batteries, fuel cells and electrochemical capacitors (Winter and Brodd, 2004). The electrochemical capacitor is a system of energy storage that is much better than batteries and fuel cells. Electrochemical capacitors made from nanoporous carbon (Frackowiak and Beguin, 2011). Nanoporous carbon is carbon that has a nano-sized pores. Nanoporous carbon has been widely used as an energy storage material due to large surface area, stable, easily polarized, and cheap. Physically porous carbon consists of a solid material that contains carbon (matrix) and empty cavities (pores) (Sembiring and Sinaga, 2003). Nanoporous carbon can be made from a variety of raw materials as long as it contains carbon such as bagasse, rice husks, coconut shell, coal, etc. (Prabowo, 2009). Bagasse is a by product of the 41


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irradiation treatment. Furthermore, the irradiatied and un-irradiatied activated carbons were characterized of pore morphology with SEM (Scanning Electron Microscope), characterization of surface area with methylene blue method, and specific capacitance with LCR-745 Meter.

Bagasse samples first washed with distilled water and then dried under the sun and in the oven. Clean and dried bagasse burned with an electric stove to fabricated and burned with a furnace at 350 ° C for 1 hour. The resulting carbon is cooled and then sieved to 100 mesh size.

METHOD Materials

Silica Extraction Bagasse carbon from the carbonization process then silicaextracted to obtain carbon-free silica. Carbon sample was added with NaOH with a concentration variation 2.5 and 5M and without extraction of silica as a comparison. The three samples were then stirred for 60 minutes accompanied by heating at a temperature of 95 oC. Then, samples were filtered and the resulting carbon is washed with distilled water until neutral pH then dried in oven at 110 oC. The oxide compounds of three types of carbon were analyzed by XRF to determine levels of silica in the carbon.

The materials used in this study was the waste bagasse, the solid ZnCl2, solid NaOH, 300 ppm methylene blue solution, distilled water, PVA powder, natrosol powder, 1 M H2SO4 solution, aluminum foil, pH universal paper, and filter paper. Tools The tools used in this study is the furnace (Muffle Furnace type 6000), Oven (type SPNISOSFD), porcelain cup, magnetic stirrer (Fisher Type 115), 100 mesh size sieve, mortar, analytical balance (Shimadzu AW220) , pumpkin plastic spray, ultrasonic cleaner (Elmasonic S40H), LCR Meter (LCR-745 type Leader), vacuum pump (Vacuubrand type ME4C), Büchner funnel, desiccator, stative, laboratory glassware, thermometer, FTIR (Shimadzu, IR Prestige21 ), SEM (Tescan Vega3 Bruker), UV-Vis Spectrometer 20D + Shimadzu.

Activation Free silica-carbon then activated using 10% ZnCl2 activators. Carbon mixed with a solution of 10% ZnCl2 then homogenized. Mixed container then sealed and allowed to stand for 24 hours. The mixture is then treated with and without irradiation of ultrasonic waves. Previously, the specified time and temperature of the irradiation optimum temperature of 15, 30, 45, and 60 ° C and a time of 10, 30, 60, 90, and 120 minutes.

Procedure Carbonization 42


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After that the two types of samples were filtered and washed with distilled water until neutral pH. Then carbon was dried in oven at 110 °C and then burned in a kiln at a temperature of 350 ° C for 1 hour.

S N mol-1) Xm (mg/g) A

Characterization Bagasse activated carbon characterized of surface area by using methylene blue method, pore morphology characterization by Scanning Electron Microscope (SEM), and characterization of specific capacitance with LCR-Meter.

Mr

: Adsorbed adsorbate weight : Wide closure by one molecule methylene blue (197 .10-20 m2) : Relative molecular mass of methylene blue (320,5 g/mol)

Determination of Spesific Capacitance of Bagasse Activated Carbon Bagasse activated carbon have been synthesized then made into electrodes and molded to measure their storage capacity. Capacitors are made by making two pieces of electrodes separated by an electrolyte hydrogels using a simple mold. In this study, the mold is made from a 1,5” PVC pipe with a length of 3 cm which one side in the cover with aluminum foil. Molding was done by mixing 2 mL 1M H2SO4, 2 mL of 5% Polyvinyl Alcohol (PVA), and 0,25 grams of carbon, then stirred. Once added to natrosol, the mixture immediately poured into a mold. After the first carbon electrode layer is formed, then a hydrogel layer of electrolyte made in the same way that a mixture of 2 mL H2SO4, 2 mL of 5% PVA, and 0,5 grams natrosol and immediately poured over the electrode layer in the mold. Once the hydrogel layer of electrolyte, then made another one like carbon electrode layer on the first layer, thus resulting electrochemical capacitor consists of two layers of carbon

Determination of Surface Area by Methylene Blue Method Determination of the surface area with methylene blue method is based on the ability of activated carbon to absorb substances methylene blue. A total of 0,3 grams of activated carbon is added to the erlenmeyer containing 50 mL of 300 ppm methylene blue solution, then closed. The mixture is stirred with a magnetic strirer for 30 minutes, then filtered. The absorbance of the filtrate then measured with UV-Vis spectrometer at a wavelength of 658 nm. Absorbance data obtained is used to calculate the concentration after adsorption of the calibration curve. Final concentration value is then used to calculate the surface area of the carbon by the following equation. S=

: Adsorben surface area (m2/g) : Avogadro number (6,022 .1023

Xm . N . a Mr 43


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electrodes flanking bagasse hydrogel layer electrolyte. Capacitors which have been printed then dried at room temperature for 3 days. Electrochemical capacitors that have been made then was storage capacity measured using LCRmeters.

Figure 1. Cleaned and dried bagasse samples

by using an electric stove for 20 minutes to be charcoal (C). At the time of combustion, the container used must be sealed to avoid direct contact with O2 in the atmosphere to prevent oxidation which can cause carbon continues to ashes. This combustion would form a lot of smoke which indicated evaporation of volatile compounds and water vapor contained in the material bagasse. Combustion was stopped when it was not formed smoke anymore. The second phase, the combustion was done by using a furnace at 350 °C for 1 hour. The optimum temperature carbonization o bagasse is 350 C. Too high temperature would cause the formation of ash. At this stage, there would be breaking of C-C bonds in lignin and cellulose in materials and non-carbon compounds will be lost. After carbonization, carbon sifted with a 100 mesh size sieve to reduce its size. Due to the small size of the carbon particles provide a large surface area. Moreover, this was done to have same size of carbon particles. Carbon bagasse was sieved with a 100 mesh size is shown in the following figure.

Carbonization Carbonization is the process of burning organic material in the raw material that would cause decomposition of the organic material and impurities expenditures where most non-carbon elements will be lost at this stage. Carbonization process bagasse is done through two stages. The first stage, carried out by burning bagasse

Figure 2. Bagasse carbon after carbonization

RESULTS AND DISCUSSION Sugarcanne Bagasse Preparation Preparation of materials made with bagasse washed with water and distilled water to be cleaned from impurities. After that, the material is dried under direct sunlight for 5 hours in 5 days, and in the oven at 110 °C for 2 hours to remove the water content in the carbon. Furthermore, bagasse materials chopped into small pieces.

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form sodium silicate (Mujiyanti, et al 2010). After that, the mixture was filtered to separate the filtrate and residue. The residue is then washed with distilled water until neutral pH. This washing is done to remove the sodium silicate which is still contained in the residue. Then carbon was dried in oven at 110 °C for 4 hours. In the silica extraction process, three types of carbons were namely bagasse without silica extraction (KatEks0), silica extracted bagasse carbon using 2.5 M NaOH (Kat-Eks2,5), and silica extracted bagasse carbon using 5 M NaOH (Kat-Eks5). This three types of carbon and oxide compounds characterized by XRF obtain the data in Table 1.

Silica Extraction The content of silica in the carbon bagasse according to Kristianingrum et al. (2011) amounted to 73.5%. According to Wei, et al (2011), extraction of silica on carbon will provide the initial structure thus generated pure carbon. In addition, if the silica in the carbon extracted, it will form more space in the carbon. In this research, the extraction of silica done by using a solution of NaOH with variation concentration of 2.5 M and 5 M, and without extraction silica as a comparison. Variations of concentration intended to determine the optimum concentration of NaOH are used to extract all of the silica. Silica extraction is done by mixing 5 grams of carbon bagasse with 100 mL of NaOH solution. The mixture is then stirred with a magnetic stirrer for 1 hour at a temperature of 95 oC. Stirring aims to optimize the extraction of silica on carbon. Beside that, the heating is done to accelerate the pace of extraction and rising temperatures will increase the amount of silica dissolved into the extractant. The reaction is here below. SiO2(s) + 2NaOH(l)  Na2SiO3(s) + H2O(aq) On silica (SiO2), O atom has high electronegativity so Si becomes more electropositive and formed intermediates [SiO2OH]– which is not stable. In this process, there will be dehydrogenation and second hydroxyl ions will bind with hydrogen to form water molecules. Two Na+ ions will balance the negative charge formed and interact with SiO32- ions to

Table 1. Oxide compound in carbon after silica extraction

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Dominant oxide compounds in the carbon bagasse were SiO2, Fe2O3, K2O, CaO, P2O5, MnO, TiO2, and SrO. While other oxide compounds only at concentrations of less than 1% of the weight of the samples analyzed. Kat-Eks0 sample containing 53.16% silica. In the sample Kat-Eks2,5 silica content is reduced to 10.93%, and finally run out on samples Kat-Eks5. It is proved that the silica in the carbon successfully extracted by using 5M NaOH. Silica-free carbon would then be activated. Activation Activation aims to activate carbon by lifting residues on the surface of the pore so that it can be produced carbon with a large surface area (Aisah, 2010). In this research, the activation done by using ZnCl2 10%. Activation of carbon bagasse done by mixing 5 grams of carbon bagasse with 60 mL of 10% ZnCl2 activator then soaked for 24 hours. Soaking done to maximize the contact between the carbon with activator so residues that cover the carbon pores will be lifted so that the pores of the carbon would be open. Thus, the active side of the carbon would be formed. The more pores are formed, the more space available for storage of electrical charge in the form of ions in the electrolyte in nanoporous carbon (Rosi, et al., 2013). After soaking, then carbon was treated with ultrasonic waves irradiation and un-irradiation. After treating

Compound

Kat-Eks0 (% w/w)

KatEks2,5 (%w/w)

KatEks5 (%w/w)

SiO2

53,15

10,93

-

Fe2O3

29,16

64,08

72,53

K2O

5,01

3,58

3,59

CaO

4,90

0,974

10,81

P2O5

3,11

0,94

0,83

MnO

2,52

6,17

6,94

TiO2

1,45

3,75

4,33

Cr2O3

0,194

-

-

ZnO

0,169

0,232

0,185

SrO

1,132

0,389

0,397

NiO

0,092

-

0,198

irradiation and un-irradiation of ultrasonic waves, the carbon then burned in a kiln at a temperature of 350 °C for 1 hour. This was done to eliminate impurities on activated carbon. Activated carbon obtained with and without irradiation of ultrasonic waves then characterized. Surface Morphology Analysis of Bagasse Activated Carbon The surface morphology of bagasse activated carbon was done by using Scanning Electron Microscope (SEM) Tescan Vega3 Bruker. 46


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irradiated activated carbon has a diameter size of 1,5 to 2 µm. While the unirradiated activated carbon has a pore diameter of 1.6 to 3 µm. In the irradiated activated carbon, more equitable distribution of pores, more number of pores, and the pore sizes tend to be smaller than the pores in un-irradiated activated carbon. In addition, the pores in irradiated activated carbon are formed up to the inside of the carbon. In contrast to un-irradiated activated carbon, which pores are formed not too good and only formed at the surface of the carbon. Better pore distribution proved that ultrasonic irradiation treatment cavitation effect, which occurs on the bubble formation and breakdown of activated carbon to form more number of pores in the irradiated carbon than un-irradiated activated carbon.

(a) (b) Figure 3. SEM image of activated carbon bagasse on a scale of 2 μm (a) without irradiation of ultrasonic waves, (b) the irradiation of ultrasonic waves Figure 3 shows the results of SEM of bagasse activated carbon with magnification on a scale of 2 μm. In both types of activated carbon either treated with irradiation or not, pores formed due to the evaporation of volatile components as well as the release of inorganic compounds that cause the formation of pores in activated carbon. There is a clear difference between irradiated activated carbon and un-irradiated activated carbon. Based on the known pore image formed on the Surface Area Analysis of Irradiated and Un-irradiated Bagasse Activated Carbon Table 2. Data of irradiated and un-irradiated bagasse activated carbon surface area

Sample

Absorbance

Final conc.

Initial conc.

(ppm)

(ppm)

Volume (L)

Carbon Weight (g)

Xm (mg/g)

Un-irradiated activated carbon

4,388

22,69791

300

0,05

0,3

46,217 00

Irradiated

4,412

21,81770

300

0,05

0,3

46,196

47

(Na.a) /Mr

S (m2/g)

3,706

171,2802

3,706

171,2030


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activated carbon

Results of surface area determination with methylene blue method showed that the irradiated activated carbon bagasse provide a larger surface area of 171.2802 m2/gram than un-irradiated bagasse activated carbon of 171.2030 m2/gram, although the difference was not significant which only amounted to 0.0772 m2/gram. This proves that ultrasonic waves irradiation affect the surface area of activated carbon. Irradiated activated carbon experience the effects of cavitation where bubbles are forming and breaking. Bubble breaking then formed more pores in the activated carbon, so that the surface area of irradiated activated was bigger than the un-irradiated activated carbon. These data correspond to pore characterization with SEM on the previous discussion, where the smaller the pore size, the more pores are formed, so that the value of the surface area of activated carbon increases.

3.5 cm, with a thickness of 0.6 cm, and weight of 3.3 grams, shown in Figure 4.

Figure 4. Electrochemical capacitors of bagasse activated carbon Electrochemical capacitors that have been made subsequently storage capacity measured using LCR-meter, so it obtained the storage capasity data of irradiated and un-irradiated bagasse activated carbon shows in Table 3. Table 3. Data of specific capacitance of irradiated and un-irradiated bagasse activated carbon Storage Electrochemical capacitance capasitor samples (F/gram)

Determination of Spesific Capacitance of Bagasse Activated Carbon Bagasse activated carbon had been synthesized then made into electrodes and printed to create a simple electrochemical capacitors. Electrochemical capacitors shaped like a sandwich, where there were two layers of electrodes sandwiching a layer of hydrogel electrolyte. Electrochemical capacitors were made had a diameter of

Un-irradiated activated carbon

0,4624 x 10-5

Irradiated activated carbon

0,3284 x 10-5

Table 3 shows the specific capacitance value of the electrochemical 48


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capacitors which the un-irradiation activated carbon has a bigger storage capasitance value gthan the irradiated bagasse activated carbon although the difference was not too significant. This indicates that ultrasonic waves irradiation affect the value of specific capacitance of activated carbon storage as a capacitor electrode. This may be influenced by the chemical content in the activated carbon due to the effect of cavitation on irradiation ultrasonic treatment.

2.

3.

CONCLUSION Ultrasonic wave irradiation treatment gives effect to the pore morphology on bagasse activated carbon. Irradiated activated carbon had smaller pore structure, a lot, and distributed evenly than un-irradiated activated carbon. The surface area of irradiated bagasse activated carbon in optimum condition at a temperature of 30 ° C for 60 minutes is 171.2802 m2/g with a specific capacitance value of 0.3284 x 105 F/gram, while the surface area of the unirradiated activated carbon was 171.2030 m2/g with a specific capacitance value of 0.4624 x 10-5 F/gram.

4.

REFERENCES 1. Aisah, S., Yulianti, E., san Fasya, A.G., 2010, Penurunan Angka Peroksida dan Asam Lemak Bebas(FFA) pada Proses BleachingMinyak Goreng Bekasoleh KarbonAktif Polong Buah Kelor (Moringa oleifera.

8.

5.

6.

7.

9. 49

Lamk) dengan Aktivasi NaCl, Alchemy, 1( 2), 53-103. Frackowiak, E., AND Beguin, F., 2001. Carbon materials for the electrochemical storage of energi in capacitors, Carbon, 39(1): 937950. Kristianingrum, S., Siswani, E.D., Fillaeli, A., 2011, Pengaruh Jenis Asam pada Sintesis Silika Gel dari Abu Bagasse dan Uji Sifat adsorptifnya Terhadap Ion Logam Tembaga (II), Skripsi, Universitas Negeri Yogyakarta. Mujiyanti, Nuryono, Kunarti, 2010, Sintesis dan karakterisasi Silika Gel dari Abu Sekam Padi yang diimobilisasi dengan 3-(Trimetoksisilil)-1propantiol. Jurnal Sains, 4(2), 150-167. Prabowo, A. L., 2009, Pembuatan Karbon Aktif dari Tongkol Jagung serta Aplikasinya untuk Adsorbsi Cu, Pb, dan Amonia, Skripsi, Universitas Indonesia, Depok. Rosi, M. Iskandar, F., Abdullah, M., Khairurrijal., 2013, Sintesis nanopori Karbon dengan Variasi Jumlah NaOH dan aplikasinya sebagai Superkapasitor, Seminar Nasional Material, ITB. Sembiring and Sinaga R., 2003, Arang Aktif (Pengenalan dan Proses Pembuatannya), USU Digital Library, Medan, http://library.usu.ac.id/download/f t/industri-meilita.pdf. Shofa, 2012, Pembuatan Karbon Aktif Berbahan Baku Ampas Tebu


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dengan Aktivasi Kalium Hidroksida, Skripsi, Universitas Indonesia, Depok. 10. Wei, X., Xiao, Li., Jin Zhou, dan Ping, Z. S., 2011, Nanoporous Carbon Derived from Risk Husk for Electrochemical Capacitor Application, Adv. Mater. Res. J., 239-242, www.scientific.net 11. Sudibandriyo, M., and Lydia, 2011, Karakteristik Luas Permukaan Karbon Aktif dari Ampas Tebu dengan Aktivasi Kimia, Skripsi, Universitas Indonesia, Depok. 12. Winter, M., dan Brodd, R.J., 2004., What are batteries, fuel cells, and supercapacitors?, Chem. Rev., (104), 4245-4269.

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Phytochemical Test, Tokxicity and Antioxidant Activity Leaves Kerehau (Callicarpa longifolia Lam.) With DPPH Method Erwin, Redda An Nisa, dan Daniel

Jurusan Kimia FMIPA Universitas Mulawarman Jl. Barong Tongkok No. 4 Gn. Kelua Samarinda. Telp. 0541-749152 Email address: [email protected]

Abstract Phytochemical analysis, toxicity test by the brine shrimp lethality test (BSLT) against Artemia salina L, and antioxidant activity evaluation of the extracts of Kerehau leaves (Callicarpa longifolia Lam.) have been carried out. The ethanol extract obtained from Kerehau leaves was concentrated by using a rotary vacuum evaporator. Furthermore, the crude extract was fractionated with n-hexane and ethyl acetate solvent, successively. The phytochemical analysis of crude extract constitutes alkaloids, phenolics, flavonoids and steroids. n-hexane fraction contains alkaloids, flavonoids and steroids and ethyl acetate fraction contain alkaloids, phenolics and flavonoids. n-Hexane fraction exhibited highest toxic activity with LC50 value 90.05 ppm against Artemia salina L and ethyl acetate fraction has the highest antioxidant activity with IC50 value 38.94 ppm compared with other extracts. Keyword: Phytochemical, toxicity, antioxidant, and Artemia salina L

Abstrak Analisis fitokimia, uji toksisitas dengan udang Artemia salina, dan uji aktivitas antioksidan terhadap ekstrak daun Kerehau (Callicarpa longifolia Lam.) telah dilakukan. Ekstrak total yang diperoleh dari hasil maserasi daun Kerehau dengan metanol, dievaporasi dengan rotary evaporator. Ektrak kasar kemudian difraksinasi dengan n-heksana dan pelarut etil asetat, secara berturut-turut. Berdasarkan hasil uji fitokimia menunjukkan bahwa ekstrak kasarl mengandung alkaloid, fenolik, flavonoid dan steroid. fraksi n-heksana mengandung alkaloid, flavonoid dan 50


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steroid. Sedangkan fraksi etil asetat mengandung alkaloid, fenolik dan flavonoid. Hasil uji toksisitas menunjukkan bahwa frakasi n-heksan dengan nilai LC50 90,05 terhadap udang Artemia salina L dan fraksi etil asetat mempunyai aktivitas antioksidan yang paling tinggi dengan nilai IC50 38,94 ppm dibandingkan dengan ekstrak yang lain. Kata Kunci: Fitokimia, toksisitas, antioksidan, dan Artemia salina L

PENDAHULUAN Sekitar 150 tumbuhan berupa semak dan pohon termasuk dalam genus Callicarpa yang tersebar di America, Asia tenggara, Pulau pulau di Pasifik, dan Australia (Harden 1992) . Sekitar 11 spesies terdaftar sebagai tumbuhan endemik di Australia, beberapa diantaranya juga terdapat di Malaysia dan Indonesia (Rasikari, 2007). Calicarpa adalah salah satu genus tumbuhan yang merupakan sumber senyawa alam dan obat-obatan tradisioanal (Harley, 2004). Ada sekita 20 jenis spesies yang telah digunakan secara etnobotani and etnomedikal. Pemanfaatan secara etnomenikal telah dilaporkan untuk mengobati hepatitis, rematik, demam, sakit kepala, pencernaan dan penyakit lainnya. Beberapa spesies Callicarpa telah dilaporkan berpotensi sebagai antikanker (Jones dan Kingnghorn, 2009). Salah satu spesies Callicarpa yang dimanfaatkan sebagai obat tradisional oleh salah satu suku asli Kalimantan yaitu suku Dayak Tunjung adalah kerehau (Callicarpa longifolia Lam.). Kerehau (Callicarpa longifolia Lam.) dimanfaatkan oleh suku Dayak Tunjung sebagai obat masuk angin dan bengkak pada bagian akar, sedangkan pada bagian daun digunakan sebagai bedak basah (Setyowati, 2010) di samping itu tanaman ini mempunyai bunga yang berwarna ungu sehingga juga biasanya ditanam sebagai tanaman hias dipekarangan rumah sekaligus sebagai tumbuhan obat (Susiarti et al, 2000). Pemanfaatan tumbuhan ini pada suku Aborigin sepertinya informasinya masih terbatas namun di north Qld (Australia), imigran Jepang mengunya Callicarpa longifolia sebagai pengganti sirih bersama dengan kapur untuk mendapatkan efek stimulan (Rasikari, 2007). Hasil penelitian sebelumnya dilaporkan telah diisolasi steroid dari fraksi kloroform (Novadiana et al, 2013) dan flavonoid dari fraksi etil asetat (Pasaribu, et al, 2014) daun Kerehau, oleh sebagai penelitian lanjutan akan dilaporkan hasil penelitian lanjutan tentang aktivitas antioksidan dari ekstrak daun Kerehau. 51


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METODOLOGI PENELITIAN Alat dan Bahan Alat-alat yang digunakan dalam penelitian ini adalah seperangkat alat destilasi, neraca analitik, blender, rotary evaporator, beaker gelas, erlenmeyer, gelas ukur, tiang statif, klem, corong pisah, tabung reaksi, pipet volume, pipet tetes, mikropipet ukuran 100-1000 µL, labu ukur, batang pengaduk, bohlam lampu, hot plate dan spektrofotometer UV-Vis. Bahan-bahan yang digunakan adalah daun tumbuhan kerehau (Callicarpa longifolia Lam.), kertas saring Whatman no. 1, aluminium foil, etanol, etil asetat, kloroform, heksana, dietil eter, H2SO4 2 M, asam asetat glasial, Bi(NO3)3.5H2O, HgCl2, HNO3 pekat, KI, FeCl3, HCl, serbuk Mg, aquadest, air laut, DPPH (2,2-diphenyl-1-picrylhidrazyl) dan Vitamin C.

PROSEDUR PENELITIAN Ekstraksi dan Fraksinasi Sampel daun kerehau (Callicarpa longifolia Lam.) yang telah dihaluskan ditimbang kemudian diekstraksi dengan cara maserasi yaitu merendam sampel dengan pelarut etanol pada suhu ruang. Filtrat yang diperoleh disaring dengan kertas saring whatman dan corong kaca. Kemudian pelarut diuapkan dengan rotary evaporator sehingga diperoleh ekstrak kasar. Selanjutnya ekstrak kasar difraksinasi dengan n-heksan kemudian dilanjutkan fraksinasi dengan etil asetat. Ektrak kasar, fraksi n-heksana dan fraksi etil asetat yang diperoleh diuji fitokimia, toksisitas dengan menggunakan larva udang Artemia salina L(Brine Shrimp Lethality Test) dan aktivitas antioksidan dengan menggunakan metode peredaman radikal bebas 2,2diphenyl-1-picrylhidrazyl (DPPH) dengan menggunakan spektrofotometer.

Uji Fitokimia Sampel masing-masing ekstrak ditimbang 10 mg dilarutkan dengan 20 mL etanol, kemudian dibagi dalam 6 tabung reaksi. Uji alkaloid dilakukan dengan pereaksi Dragendroff, uji steroid/triterpenoid dengan pereaksi Lieberman-Burchard, uji flavonoid dengan pita Mg dan HCl pekat, uji fenolik dengan penambahan larutan FeCl3 dan uji saponin dengan cara penambahan air panas kemudian dikocok kuat. 52


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Uji Toksisitas (Brine Shrimp Lethality Test) Sampel masing-masing ekstrak ditimbang 1 mg, dilarutkan dalam 100 µL DMSO sambil diaduk, kemudian diencerkan dengan 150 µL air laut sehingga volume total menjadi 250 µL. Selanjutnya, sampel yang sudah diencerkan diambil 200 µL lalu diencerkan lagi dengan 600 µL aquades. Volume total menjadi 800 µL, sehingga konsentrasi menjadi: 200µL⁄250µL × 1 mg 0.8 = = 1000 ppm 800 µL 800µL Larutan kontrol dibuat sama dengan prosedur di atas tanpa menggunakan sampel. Bibit udang (±1000 bibit) dimasukkan ke dalam 100 mL air laut yang sudah disaring dengan menggunakan aquarium kecil selama 48 jam diberi pencahayaan. Setelah itu benih udang siap untuk uji toksisitas. Dua plat mikro standar masing-masing disiapkan untuk plat uji dan plat kontrol. Ke dalam baris I dan II masing-masing tiga kolom, sampel dimasukkan 100 µL pada plat uji dan 100 µL larutan kontrol pada plat kontrol. Pada larutan baris II diencerkan dengan 100 µL air laut kemudian diaduk, kemudian dipipet kembali 100 µL dimasukkan ke dalam baris III, larutan baris III diencerkan kembali dengan 100 µL air laut sambil diaduk dan dimasukkan ke dalam baris dan dilakukan dengan cara yang sama sampai baris terakhir. Sehingga konsentrasi larutan untuk masing-masing baris sebagai berikut, baris I = 1000 ppm, baris II = 500 ppm, baris III = 250 ppm, baris IV = 125 ppm, baris V = 62,5 ppm, baris VI = 31,25 ppm, baris VII = 15,625 ppm, dan baris VIII = 7,8 ppm. Selanjutnya ke dalam larutan sampel pada plat uji dan larutan kontrol pada plat kontrol ditambahkan 100 µL air laut yang mengandung 8-15 larva udang, kemudian dibiarkan selama 24 jam. Setelah itu dihitung jumlah rata-rata larva udang yang mati dan yang hidup untuk setiap baris pada plat uji. Nilai LC50 lalu ditentukan dengan uji probit menggunakan SAS (Statistical Analysis System).

Uji Aktivitas Antioksidan Pengujian aktivitas antioksidan dilakukan dengan menggunakan spektrofotometer pada suhu kamar (25 oC) dengan panjang gelombang antara 512-517 nm namun dicari gelombang 53


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optimumnya terlebih dahulu menggunakan larutan blanko dan larutan DPPH (2,2-diphenyl-1picrylhidrazyl) digunakan sebagai radikal bebas untuk pengujian. Larutan DPPH dibuat dengan cara menimbang DPPH dan dilarutkan dalam etanol tepat pada konsentrasi 0,024 mg/mL. Ekstrak sampel sebanyak 3 mg dilarutkan dalam DMSO sehingga didapat konsentrasi 100 ppm. Untuk masing-masing ekstrak ditimbang 20 mg, kemudian dilarutkan dengan etanol sampai volumenya 40 mL. Dengan demikian konsentrasi larutan ekstrak sampel (ekstrak kasar etanol dan masing-masing fraksi) adalah 500 ppm. Ekstrak kasar dan fraksi n-heksana dengan konsentrasi 500 ppm diencerkan untuk mendapatkan konsentrasi 12,5; 25; 50; 75 dan 100 ppm dengan menggunakan mikro pipet dan masing-masing konsentrasi dibuat 3 kali pengulangan. Sedangkan pada fraksi etil asetat dibuat seri konsentrasi dalam 3; 5; 12,5; 25; 50; 75 dan 100 ppm. Untuk pembanding (vitamin C baku) ditimbang sebanyak 1 mg dan dilarutkan dengan etanol sampai volumenya 1000 mL menggunakan labu ukur coklat, sehingga didapat larutan induk vitamin C dengan konsentrasi 1000 ppm, kemudian diambil 1 mL larutan induk vitamin C dan dilarutkan dengan etanol sampai volumenya 10 mL menggunakan labu ukur coklat, sehingga didapat konsentrasi vitamin C 100 ppm. Setelah itu, dari konsentrasi vitamin C 100 ppm dibuat seri konsentrasi larutan vitamin C dengan konsentrasi berturut-turut 3; 5; 12,5; 25; 50 75 dan 100 ppm dengan menggunakan mikro pipet dan masing-masing konsentrasi dibuat 3 kali pengulangan. Selanjutnya masing-masing konsentrasi ekstrak dan vitamin C dipipet sebanyak 1 mL dan dimasukan ke dalam tabung reaksi. Kemudian ditambahkan 1 mL larutan DPPH 0,024 mg/mL, dihomogenkan dan dibiarkan selama 30 menit di tempat gelap. Selanjutnya diukur absorbansinya dengan spektrofotometer UV-Vis pada panjang gelombang optimum. Aktivitas antioksidan ditentukan berdasarkan persentase daya hambat radikal bebas. Analisa kuantitatif terhadap aktivitas penghambatan radikal/DPPH dilakukan dengan menggunakan rumus :

%AA = 100 – {[(AB – AA)] x 100 / AKN} Keterangan : %AA = Persentase aktivitas antioksidan 54


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AA

= Absorbansi blanko (berisi 1 mL ekstrak dalam etanol + 1 mL etanol)

AB

= Absorbansi sampel (berisi 1 mL ekstrak dalam etanol + 1 mL DPPH)

AKN

= Absorbansi kontrol negatif (berisi 1 mL etanol + 1 mL DPPH) (Karamac et al., 2002) Pengujian ini bertujuan untuk mengindikasi adanya aktivitas antioksidan yang

ditunjukkan melalui dekolorisasi warna radikal DPPH dari ungu menjadi kuning sampai bening dan terjadi penurunan nilai absorbansi ekstrak terhadap kontrol, yang ditunjukkan pada monitor pada spektrofotometer. Jika terdapat indikasi tersebut dapat dinyatakan bahwa telah terjadi penghambatan ekstrak terhadap radikal DPPH, yang artinya ekstrak memiliki potensi antioksidan karena telah mampu menghambat kerja radikal bebas.

HASIL DAN PEMBAHASAN

Ekstraksi dan Fraksinasi Sampel daun Kerehau (Callicarpa longifolia Lam.) dimaserasi

dengan etanol secara

berulang sampai larutan ekstrak tidak berwarna lagi. Kemudian maserat disaring dan filtratnya dipekatkan menggunakan rotary evaporator. Selanjutnya difraksinasi dengan pelarut n-heksana dan etil asetat secara berturut-turut. Adapun berat dari ekstrak total, fraksi n-heksan dan fraksi etil asetat yang diperoleh masing-masing adalah 18,79 gram, 5,30 gram dan 4,47 gram, seperti yang tercantum dalam table 1 berikut.

Tabel 1 Berat dari ekstrak kasar dan masing-masing fraksi No. Jenis Ekstrak 1.

Ekstrak kasar

Berat (gram) 18,79

etanol 2.

Ekstrak fraksi

5,30

n-heksana 3.

Ekstrak fraksi

4,47

etil asetat 55


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Uji Fitokimia Berdasarkan hasil uji fitokimia yang telah dilakukan terhadap ekstrak total, fraksi nheksana dan fraksi etil asetat dari tumbuhan kerehau (Callicarpa longifolia Lam.) diketahui jenis senyawa metabolit sekunder yang dapat dilihat pada tabel 2 berikut.

Tabel 2 Hasil uji fitokimia dari ekstrak kasar dan masing-masing fraksi daun tumbuhan kerehau

Jenis Senyawa

Ekstrak Total

Alkaloid Fenolik Flavonoid Saponin Steroid Triterpenoid

+ + + + -

Jenis Ekstrak Fraksi Fraksi n-Heksana Etil Asetat + + + -

+ + + -

Keterangan : + : Mengandung senyawa metabolit sekunder ˗ : Tidak mengandung senyawa metabolit sekunder

Uji Toksisitas (Brine Shrimp Lethality Test) Sebagai skrining awal senyawa toksik dilakukan uji toksisitas dengan menggunakan larva udang (Artemia salina L.). Hasil uji toksisitas ini dapat diketahui dari jumlah kematian larva udang yang dinyatakan dalam LC50. Nilai LC50 merupakan angka yang menunjukkan konsentrasi ekstrak yang dapat menyebabkan kematian sebesar 50% dari jumlah hewan uji. Berdasarkan perhitungan dengan analisis probit SAS (Statistic Analysis System) terhadap ekstrak total, fraksi n-heksana dan fraksi etil asetat pada daun tumbuhan kerehau (Callicarpa longifolia Lam.) diperoleh LC50 (Lethal Concentration 50%) yang diperlihatkan pada tabel 3 berikut.

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Tabel 3 Nilai LC50 uji mortalitas larva udang ekstrak kasar etanol dan masing-masing fraksi No.

Jenis Ekstrak

LC50 (ppm)

1.

Ekstrak kasar

447,90

2.

fraksi n-heksana

90,04

3.

fraksi etil asetat

275,00

Menurut Meyer (1982), nilai tersebut menunjukkan ekstrak termasuk dalam tingkat toksik yang berkisar pada 31 ppm ≤ LC50 ≤ 1000 ppm. Berdasarkan hasil perhitungan diperoleh bahwa ekstrak kasar mempunyai potensi toksisitas yang paling rendah dibandingkan dengan fraksi n-heksana dan fraksi etil asetat. Hal tersebut berkaitan dengan senyawa metabolit sekunder yang terkandung dari masing-masing ekstrak, di mana pada kadar tertentu memiliki tingkat toksik yang lebih tinggi sehingga dapat menyebabkan kematian yang lebih besar pada larva udang.

Uji Aktivitas Antioksidan Adapun data uji yang dihasilkan dari uji aktivitas antioksidan dengan metode peredaman radikal DPPH untuk masing-masing ekstrak dan vitamin C dapat dilihat pada tabel berikut ini 4.

Tabel 4 Persen peredaman radikal DPPH (%AA) dari ekstrak total, fraksi n-heksan, fraksi etil asetat, dan vitamin C pada berbagai konsentrasi

Sampel Ekstrak total Fraksi n-heksan Fraksi etil asetat Vitamin C

3 ppm 39,62% 44,25 %

5 ppm 40,57% 48,16 %

Konsentrasi 12,5 ppm 25 ppm 50 ppm 35,75% 39,66% 46,44% 27,59% 33,33% 39,54% 42,64% 45,98% 54,37% 51,03 % 55,17 % 67,47 %

75 ppm 54,48% 46,67% 60,80 % 76,44 %

100 ppm 60,85% 53,33% 65,98% 90,92 %

Berdasarkan hasil data di atas, maka dapat dilihat grafik hubungan antara konsentrasi masingmasing ekstrak terhadap peredaman radikal DPPH (%AA) pada gambar 1 berikut.

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Gambar 1. Kurva hubungan antara %AA Vs masing masing ekstrak dan vitamin C sebagai pembanding

Adapun besarnya nilai IC50 pada ekstrak total, fraksi n-heksana, fraksi etil asetat dan vitamin C sebagai pembanding dapat diketahui dari persamaan regresi linier sederhana pada grafik di atas. Nilai IC50 untuk ekstrak total diperoleh 61,38 ppm, fraksi n-heksana diperoleh 87,18 ppm, pada fraksi etil asetat diperoleh 38,94 ppm sedangkan pada vitamin C diperoleh 12,30 ppm. Parameter yang digunakan untuk uji penangkapan radikal DPPH adalah nilai IC50. IC50 didefinisikan sebagai besarnya konsentrasi ekstrak yang dapat menghambat aktivitas radikal bebas DPPH sebesar 50 %. Nilai IC50 diperoleh dari suatu persamaan regresi linear yang menyatakan hubungan antara konsentrasi ekstrak uji dengan persen penangkapan radikal. Nilai IC50 yang semakin kecil menunjukkan aktivitas antioksidan pada bahan yang diuji semakin besar. Secara spesifik, suatu senyawa dikatakan sebagai antioksidan sangat kuat apabila nilai IC50 kurang dari 50 ppm, kuat apabila nilai IC50 antara 50-100 ppm, sedang apabila nilai IC50 antara 101-150 ppm dan lemah apabila nilai IC50 lebih dari 151 ppm. Berdasarkan klasifikasi di atas, dapat disimpulkan bahwa pada ekstrak kasar dan fraksi nheksana memiliki potensi sebagai antioksidan kuat, karena nilai IC50 yang diperoleh berada dalam rentang 50-100 ppm, yaitu diperoleh nilai IC50 sebesar 61,38 ppm pada ekstrak kasar dan 87,18 ppm pada fraksi n-heksana. Sedangkan pada fraksi etil asetat nilai IC50 yang diperoleh sebesar 38,94 ppm sehingga aktivitas antioksidan yang dimiliki fraksi etil asetat dapat dikategorikan sangat kuat, dikarenakan nilai IC50 yang dimiliki kurang dari 50 ppm. Fraksi etil 59


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asetat memiliki aktivitas antioksidan paling kuat jika dibandingkan dengan ekstrak yang lain, hal ini dikarenakan terdapat kandungan senyawa golongan alkaloid, fenolik dan flavonoid yang dimiliki fraksi etil asetat yang sudah diketahui memiliki aktivitas sebagai antioksidan. Dugaan ini diperkuat di mana sebelumnya telah diisolasi flavonoid dari fraksi etil asetat daun Kerehau (Pasaribu et al, 2014). Untuk ekstrak total juga mengandung senyawa alkaloid, fenolik, flavonoid dan steroid, namun tidak sekuat pada fraksi etil asetat dikarenakan belum terkonsentrasi, masih bercampur antara senyawa yang polar dan non polar. Sedangkan pada fraksi n-heksana mengandung senyawa alkaloid, flavonoid dan steroid. Aktivitas antioksidannya tidak sekuat bila dibandingkan dengan ekstrak kasar etanol dan fraksi etil asetat, diduga karena tingginya kandungan steroid sehingga tidak dapat bersinergis dengan baik sebagai antioksidan. DPPH bereaksi dengan senyawa antioksidan melalui pengambilan atom hidrogen dari senyawa antioksidan untuk mendapatkan pasangan elektron. Senyawa yang bereaksi sebagai penangkap radikal akan mereduksi DPPH yang dapat diamati dengan adanya perubahan warna DPPH dari ungu menjadi kuning ketika elektron ganjil dari radikal DPPH telah berpasangan dengan hidrogen dari senyawa penangkap radikal bebas yang akan membentuk DPPH-H tereduksi. Antioksidan fenolik biasanya digunakan untuk mencegah kerusakan akibat reaksi oksidasi pada makanan, kosmetik, farmasi dan plastik. Senyawa ini mempunyai aktivitas sebagai penangkap radikal bebas sehingga dapat dimanfaatkan sebagai obat untuk mencegah penyakit yang disebabkan oleh radikal bebas seperti penyakit kanker. Flavonoid merupakan senyawa alami yang tergolong dalam sebagai senyawa aromatis merupakan senyawa pereduksi yang baik, menghambat banyak reaksi oksidasi, baik secara enzim maupun non enzim. Senyawa flavonoid dapat bertindak sebagai antioksidan dan merupakan donor hidrogen, seperti halnya dengan fenolik, radikal bebas yang terbentuk akibat dari donor hidrogen mempunyai energi yang rendah sebagai akibat dari terjadinya delokalisasi elektron dalam cincin benzen sebelum menjadi senyawa yang stabil.

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KESIMPULAN Berdasarkan hasil uji fitokimia terdapat beberapa jenis metabolit sekunder pada ekstrak kasar etanol yaitu, alkaloid, fenolik, flavonoid dan steroid, sedangkan pada fraksi n-heksana terdapat alkaloid, flavonoid dan steroid dan pada fraksi etil asetat terdapat alkaloid, fenolik dan flavonoid. Berdasarkan hasil uji BSLT, fraksi yang memiliki sifat toksik paling tinggi adalah fraksi n-heksan dengan nilai LC50 sebesar 90,05 dan fraksi yang paling baik digunakan sebagai antioksidan adalah fraksi etil asetat dengan IC50 sebesar 38,94 ppm.

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STUDY OF COMPOUNDS FROM EXTRACT OF Melochia umbellata (Houtt.) Stapf var. Degrabrata K. (PALIASA) LEAVES THAT HAS POTENTIAL AS ANTIBACTERIAL

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