Summary: Batch experiments of adsorption of heavy metals cations from aqueous solution by using carboxymethyl cellulose-graft-poly(acrylic acid)/monmorilonite (CMC-g-PAA/MT) hydrogel composite were carried out. The parameter such as different pH and the presence of other ions as competitor were studied to observe their effects on the adsorption capacity of the hydrogel composite. The results showed that the adsorption of metal ions by the hydrogels was higly pH dependent, and maximum adsorption was obtained at pH 5.0. At this pH, the adsorption capacities of hydrogels for the Pb 2þ and Zn 2þ ions were 146.19 mg/g and 286.67 mg/g, respectively. The hydrogels can be regenerated after releasing metal ions by washing with low pH solution and reused two times. Based on the scanning electron microscope (SEM) images and Fourier transform infrared spectroscopy (FTIR) spectra before and after adsorption by the hydrogels revealed that the complex formation between heavy metal ions and carboxyl groups of the hydrogels was the main adsorption mechanism.

ABSTRAKMicrobial fuel cell (MFC) merupakan salah satu teknologi sel bahan bakar alternatif yang dapat diperbarui. MFC memanfaatkan proses oksidasi senyawa kimia oleh biokatalis untuk menghasilkan energi listrik daya rendah. Tujuan dari penelitian ini adalah mengetahui kinerja MFC dengan dan tanpa mediator elektron metilen biru (MB) menggunakan biokatalis Acetobacter aceti dan substrat glukosa agar diperoleh energi listrik. Metode yang dilakukan adalah peremajaan kultur A. aceti, persiapan inokulum, persiapan reaktor MFC, persiapan media MFC dengan substrat glukosa 2% dengan dan tanpa mediator MB, pencuplikan secara periodik, penentuan kurva pertumbuhan, arus, potensial, kerapatan daya, energi, kadar glukosa dan tingkat keasaman (pH). Hasil penelitian menunjukkan bahwa MFC dengan mediator menghasilkan kuat arus sebesar 0,040 mA, potensial 878 mV, kerapatan daya 0,395 mW/cm 2 , energi maksimum 3,685 kJ, pemanfaatan glukosa 93,02% dan pH akhir 3,33, sedangkan MFC tanpa mediator menghasilkan kuat arus 0,035 mA, potensial 773 mV, kerapatan daya 0,290 mW/cm 2 , energi maksimum 2,434 kJ, pemanfaatan glukosa 90,16% dan pH akhir 3,24. Perolehan kerapatan daya pada kedua jenis MFC masih tergolong kecil dan tidak berbeda secara signifikan. Berdasarkan hasil penelitian dapat disimpulkan bahwa penggunaan mediator MB hanya berpengaruh terhadap perolehan potensial pada MFC dengan kondisi perlakuan yang diterapkan dalam penelitian ini.Kata kunci: Microbial fuel cell, Acetobacter aceti, metilen biru, mediator elektron THE EVALUATION OF METHYLENE BLUE AS ELECTRON MEDIATOR IN MICROBIAL FUEL CELL WITH ACETOBACTER ACETI BIOCATALYST ABSTRACTMicrobial fuel cell (MFC) is one of alternative renewable fuel cell technologies. MFC utilizes oxidation processes of chemical compounds by biocatalyst to produce low power electrical energy. The objective of the present study was to investigate the performance of MFC with and without methylene blue (MB) as electron mediator utilizing Acetobacter aceti as biocatalyst and glucose as substrate to generate electrical energy. Methods performed comprise of the A. aceti bacterial culture rejuvenation, preparation of the inoculum, preparation of the MFC reactor, preparation of MFC media 2% of glucose with