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Abstrak :
Pada penelitian ini, mineral gibsit (Al2(OH)6) digunakan sebagai adsorben untuk adsorpsi fosfat pada media air. Dilakukan empat perlakuan pada mineral gibsit untuk mengetahui perbedaan daya adsorpsinya. Gibsit di purifikasi dengan metode Tributh Lagaly dan diinterkalasi dengan LiCl selama 24 jam untuk meningkatkan daya adsorpsi nya. LiCl yang terinterkalasi ke dalam gibsit akan membentuk struktur [LiAl2(OH)6]+ dan akan terjadi pertukaran anion Cl- pada saat proses adsorpsi pada lapisan interlayer gibsit. Gibsit hasil purifikasi terinterkalasi litium (LiG purifikasi) memiliki kapasitas adsorpsi paling besar dan pH 4,5 merupakan kondisi dimana gibsit memiliki kapasitas adsorpsi optimum sebesar 5,173 mg P/g gibsit dan berdasarkan data hasil EDX terdapat unsur fosfor sebesar 1,04% (%Wt). Daya adsorpsi menurun seiring menurunnya jumlah spesi ion H2PO4-/HPO42- dalam larutan. Hasil ini menunjukkan LiG purifikasi dapat digunakan sebagai adsorben alternatif untuk adsorpsi fosfat pada air. ......In this study, gibbsite mineral (Al2(OH)6) was used as an adsorbent for the adsorption of phosphate in water. There are 4 treatments for gibbsite mineral to know the differences in adsorption capacity. In this study, Tributh Lagaly method was applied for purification of gibbsite. Gibbsite was intercalated with LiCl for 24 hours to increase the adsorption. LiCl intercalatig into gibbsite giving a structure of [LiAl2(OH)6]+ and anion exchange process of Cl- will occur during the adsorption process on the gibbsite interlayer. Purified and lithium-intercalated Gibbsite (purified LiG) in the aquos solution at pH 4,5 has given the highest adsorption capacity of 5.173 mg P/g gibbsite when 0,3 g of gibbsite was applied and based on the results of EDX measurement, it contained 1.04% (%Wt) of elemental phosphorus. The adsorption decreased with decreasing amount of H2PO4-/HPO42- species. These results showed purified LiG can be used as an adsorbent for phosphate removal from water.

Abstrak :
ABSTRACT
Zeolite Clinoptilolite from Lampung, located in South of Sumatra, had been modified with surfactant hexadecyltrimethylammonium bromide (HDTMA-Br) as chromate anion exchanger. Surfactant modified zeolite (SMZ) Clinoptilolite in particle size range of 1.5 - 2.0 mm, which contained 196.7 mmol HDTMA-Br/kg zeolite, was used for anion exchange of chromate at neutral pH. This experiment was conducted in a glass column filled with 5 gram SMZ. The breakthrough chromate exchange capacity was found 1.262 mg/g SMZ, while the total capacity was found 2.107 mg/g SMZ. The regeneration of SMZ saturated with chromate was conducted using a mixed solutions of 0.28 M Na2CO3 and 0.5 M NaOH, compared with using a solution of 0.01 M Na2S2O4. The desorption of chromate achieved 92% with the mixed solutions of Na2CO3 and NaOH and 90% with the Na2S2O4 solution. The regenerated SMZ with Na2CO3-NaOH solutions was prior washed with HCl solution to remove the carbonate from SMZ, before being used for chromate sorption again. Its breakthrough capacity was reduced to 1.074 mg/g SMZ, and to 0.724 mg/g SMZ when regenerated with Na2S2O4 solution. These results indicated that regeneration of SMZ affected its exchange capacity for anion chromate. However, it is still could be acceptable, when Na2CO3/NaOH solutions were used for the regeneration of SMZ saturated with anion chromate.

Abstrak :
Enzim selulase merupakan enzim hidrolase yang mengkatalisis reaksi pemecahan selulosa menjadi unit glukosa. Enzim ini akan digunakan dalam pemanfaatan limbah pertanian (dedak padi) yang kaya akan selulosa untuk dijadikan senyawa lain seperti bioetanol. Pada penelitian ini telah dilakukan isolasi dan pemurnian enzim selulase dari mikroorganisme jamur Trichoderma viride (T051) melalui fermentasi padat menggunakan dedak padi sebagai substratnya. Pemurnian ekstrak kasar enzim dengan pengendapan bertingkat (fraksinasi) menggunakan garam ammonium sulfat, menghasilkan aktivitas spesifik selulase paling tinggi pada tingkat kejenuhan ammonium sulfat 20 -50% (11,4530 mU/mg) dengan tingkat kemurnian 5,3 kali dari ekstrak kasarnya. Pemurnian lebih lanjut dengan kromatografi kolom penukar anion (DEAE-Streamline) menghasilkan 6 puncak protein dengan aktivitas CMCase. Puncak protein ke-1 memiliki aktivitas spesifik paling tinggi (85,6703 mU/mg) dengan tingkat kemurnian 39,1 kali dari ekstrak kasarnya. Aktivitas selulolitik enzim ini ditentukan sebagai aktivitas CMCase (endoglukanase) menggunakan substrat CMC (carboxymethyl cellulose). Enzim selulase hasil pemurnian parsial memiliki aktivitas optimum pada pH 5,5 dan suhu inkubasi 50oC dan enzim ini diinhibisi oleh ion-ion Mg2+, Mn2+, dan Cu2+ (konsentrasi ion logam 100 mM) dengan persen inhibisi berturut-turut sebesar 16,4; 64,2; 60,2 %.

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Cellulase is a hydrolase enzyme that catalyzes the reaction of the breakdown of cellulose into glucose units. This enzyme will be used in the utilization of agricultural waste (rice bran) that is rich in cellulose to be used as other compounds such as bioethanol. In this study has been carried out isolation and purification of the cellulase from Trichoderma viride fungal microorganisms (T051) through solid fermentation using rice bran as a substrate. Purification of crude enzyme extract with multilevel deposition (fractionation) using ammonium sulfate salt, generating the highest specific activity of cellulase (11.4530 mU / mg) at 20 -50% level of saturation of ammonium sulfate, with a purity level of roughly 5.3 times of the extract. Further purification by anion-exchange chromatography column (DEAE-Streamline) produces 6 protein peaks with CMCase activity. Peak-1 protein to have the highest specific activity (85.6703 mU / mg) with a purity level of roughly 39.1 times of the extract. Cellulolytic enzyme activity was determined as CMCase activity (endoglucanase) using the substrate CMC (carboxymethyl cellulose). Partial purification of cellulase enzyme has optimum activity at pH 5.5 and incubation temperature 50oC, and this enzyme had inhibition by ions Mg2+, Mn2+, and Cu2+ with inhibition percent respectively at 16.4, 64.2, 60. 2%.

Abstrak :
ABSTRACT
There are many conventional technologies used for recovery of precious metals from wastewater, but most of them are chemical intensive and consume high energy. This paper focuses on silver recovery using bio-electrochemical system (BES), which basically consists of two separated chambers, the anode and cathode chamber. The anolyte, containing either acetate or glucose as substrate, was fed into the anode chamber, in which microorganisms were employed to produce electrons through anaerobic oxidation. The catholyte was a synthetic mixed metals solution containing silver Ag(I), copper Cu(II), and iron Fe(III), which acted as terminal electron acceptors. Two BES reactors, in which anion exchange membrane (AEM) and a cation exchange membrane (CEM) served as separators, were investigated. Experiments were conducted at different initial Fe(III) concentrations (10 mM and 20 mM), while the concentrations of Ag(I) (10 mM), and Cu(II) (1 mM), were kept constant. The silver recovery obtained in the CEM-based reactor (> 99%) was higher than that in AEM-based reactor (58-75%). However, diffusion of Ag(I), Fe(III), and Cu(II) through the CEM was unavoidable. In terms of power generation, a power density of 4515.63 mW/m3 was found in AEM-based reactor, which was higher than that in CEM-based reactor (1542.56 mW/m2). However, the substrate loss was found in the AEM-based reactor due to the transport of negative-charged organic matter through the AEM, which caused a fast decrease of cell voltage. This study successfully demonstrated the feasibility of using a bio-electrochemical system to recover silver coupled with power generation from a synthetic mixed metals solution.