Bismuth oxide synthesis using solution combustion method fuelled by hydrazine and urea has been conducted. This study aims to examine the effect of the applied fuels, urea and hydrazine, on product characteristics and photocatalytic activity in degrading rhodamine B dye. Bismuth oxide synthesis was initiated by dissolving bismuth nitrate pentahydrate (Bi(NO3)3.5H2O) in a nitric acid solvent. Fuel was added and then stirred. The solution formed was heated at 300 ºC for 8 hours. The product obtained was then calcined at 700 ºC for 4 hours. Bismuth oxide synthesized with urea (BO1) and hydrazine (BO2) as fuels both obtained form of yellow powder. The formation of bismuth oxide is indicated by the vibrations of the Bi–O–Bi and Bi–O groups and the crystal structure of a-Bi2O3 in both products. Photocatalytic activity test showed that BO1 has a photocatalyst activity in degrading rhodamine B higher than that of BO2 with constant values of  3.83×10-5 s-1 and 3.43×10-5 s-1, respectively. The high photocatalytic activity can be examined through several factors, such as: band gap values, crystal structure, morphology, and surface area, acquired as a result of the use of different fuels in the synthesis process. Copyright © 2020 BCREC Group. All rights reserved

Telah dilakukan penelitian pengolahan limbah cair industri batik dengan metoda elektrokoagulasi menggunakan besi bekas sebagai elektroda yang bertujuan untuk memisahkan zat warna naftol dari limbah. Selama proses elektrokoagulasi logam besi mampu membentuk Fe(OH)3 yang berperan sebagai adsorben zat warna, karena floks Fe(OH)3 mampu mengadsorpsi zat warna naftol sehingga zat warna dapat dipisahkan dari limbah. Pada proses elektrokoagulasi dilakukan penentuan kondisi terbaik yang meliputi potensial aplikasi, variasi pH dan waktu elektrolisis. Hasil penelitian menunjukkan bahwa diperoleh potensial aplikasi sebesar 5 volt dengan pH terbaik 2 dengan waktu elektrolisis selama 15 menit. Pada temperatur kamar, elektrokoagulasi limbah cair batik memberikan penurunan absorbansi sebesar 98,53%, sedangkan penurunan kandungan COD, TSS dan kekeruhan masing-masing adalah 83,64%, 99,27% dan 98,57%. Data FTIR menunjukkan adanya kemiripan serapan yang muncul antara limbah sebelum elektrolisis dan endapan hasil elektrolisis. Hal ini menunjukkan bahwa sebagian besar zat warna telah dapat dipisahkan dari limbah cair dan metoda ektrokoagulasi dapat diaplikasikan untuk mengatasi limbah cair berwarna.

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Study on decolourization of remazol black B (RBB) solution has been performed in a scale up reactor. As an artificial waste, the dye sample that contains azo groups is difficult to decompose under ordinary environmental conditions so it requires further treatment before discharging to open aquatic system. Many efforts have been reported and further developed toward other azo dyes. One of an outstanding approach is Fenton method. This study modified the method with PbO2 rather than Fe2+. In this modification, the dyestuff was degraded by radical •OH resulting from reaction between H2O2 and Pb2+ ion generated from PbO2. In Preliminary works, decolourization was performed and optimized in lab-scaled. Analysis were conducted and the best condition was applied to decolorize the sample in a scale-up size. Characteristics of the reactor was also determined. Results showed that at optimum condition, 100 mL of 50 ppm remazol black B was decolorized up to 98.82 % within 15 minutes. On scale up to 1 L-sized reactor, within the time highest percentages of remazol black B decolourization was reached 82.02 % by addition of 10 % H2O2 and COD decrease to 98.96 %. In the 1 L reactor, RBB sample with concentration of 50 ppm, PbO2 1 gram and H2O2 10 % obey the proposed decolourization equation of D = -0,0011x2 + 0.5705x – 0.6788 with x = volume peroxide (in mL), D = percent of decolourization.

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Heparin, an active sulfate group material, grafted onto blend membrane citric acid cross-linked chitosan/poly (vinyl alcohol)-poly(ethylene glycol) (PVA-PEG) to improve the membrane properties. The physical tests shown that grafting reaction of citric acid crosslinked chitosan increased the mechanical strength and membrane swelling. The permeability test results, it was found that the grafted chitosan membrane was improved permeability of both urea and creatinine as compared to chitosan pure and chitosan crosslinked membrane. The negative charge of the sulphonate group of heparin increased the number of the active side of the carrier in the membrane, which then correlated to the membrane’s permeability process.

Microbial Fuel Cell (MFC) adalah sistem bioelektrokimia yang mengubah energi kimia menjadi energi listrik yang melibatkan reaksi reduksi dan oksidasi dengan memanfaatkan mikroba. Tujuan penelitian ini adalah menentukan beda potensial yang dihasilkan sistem MFC pada substrat whey tahu menggunakan mikroba Lactobacillus bulgaricus dengan variasi bahan buffer fosfat dan pH. Penelitian ini menggunakan sistem MFC dual chamber dengan jembatan garam sebagai penghantar proton dari kompartemen anoda ke kompartemen katoda. Kompartemen anoda berisi campuran mikroba yang sudah dikultivasi dan buffer kalium fosfat atau buffer natrium fosfat dengan variasi pH, yaitu 5,5; 6; 6,5; 7. Pada katoda berisi elektrolit KMnO4 0,2 M, buffer fosfat, dan pH dengan variasi yang sama. Pengukuran beda potensial dilakukan pada suhu ruang selama 30 jam. Pengukuran kelistrikan pada sistem MFC menggunakan buffer kalium fosfat pada empat pH berbeda yaitu 7 ; 6,5 ; 6 ; 5,5 dalam 100 mL volume sistem masing-masing menghasilkan beda potensial yaitu sebesar 42,2 mV; 32 mV; 30 mV; 29,3 mV. Sedangkan dalam sistem buffer natrium fosfat dan 100 mL dengan variasi pH yang sama berturut-turut adalah 20 mV ; 18,6 mV ; 17 mV ; 4 mV. Buffer kalium fosfat menghasilkan beda potensial yang lebih besar dibandingkan dengan buffer natrium fosfat.

A r t i c l e I n f oA b s t r a c t