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Electrical energy needs in Indonesia are expected to continue to rise. The use of petroleum as a source of energy still dominates, although oil reserves in Indonesia are increasingly being depleted. Therefore, there is a need to develop alternative sources of sustainable energy, such as microbial fuel cell (MFC). In this study, Lactobacillus bulgaricus was used as an electricity producer in a dual-chamber MFC reactor. We investigated the maximum electrical energy by varying the bacterial optical density (OD), the operational time of MFC, the reactor volume, the electrolyte solution, and the configuration of MFC reactor. In this study, the maximum electrical energy (201.8 mW/m 2 ) was generated at an OD of 0.5 in an MFC reactor series using potassium permanganate as the electrolyte solution. AbstrakOptimasi Kinerja Microbial Fuel Cell (MFC) dengan Bakteri Lactobacillus bulgaricus. Kebutuhan energi listrik di Indonesia diperkirakan akan terus meningkat. Namun penggunaan minyak bumi sebagai sumber penghasil energi masih mendominasi, padahal cadangan minyak bumi di Indonesia kian menipis. Oleh karena itu, perlu dikembangkan alternatif penghasil sumber energi yang berkelanjutan, salah satunya adalah microbial fuel cell (MFC). Pada penelitian ini, digunakan bakteri Lactobacillus bulgaricus sebagai penghasil listrik pada reaktor MFC dual-chamber. Untuk memperoleh energi listrik yang maksimum, dilakukan variasi optical density (OD), waktu operasi, volume reaktor, larutan elektrolit, dan konfigurasi reaktor MFC. Dari penelitian ini, dihasilkan energi listrik maksimum berupa power density sebesar 201,9 mW/m 2 pada reaktor MFC seri dengan OD 0,5 dan kalium permanganat sebagai larutan elektrolit.

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In this research, we studied the preparation of nanochitosan from the addition of potassium persulfate as an initiator for monomer polymerization and monocarboxylic acid-namely acetic acid, lactic acid, and formic acid-to a chitosan solution. To obtain the dried form of chitosan nanoparticles, we investigated the effects of oven and spray drying systems toward the physicochemical properties and morphology of chitosan nanoparticles. Successfully prepared chitosan nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR), Field Emission Scanning Microscopy/Energy Dispersive X-ray Analysis (FESEM-EDX), and a particle size analyzer (PSA). The structures of nanochitosan prepared in different acids were quite similar based on the FTIR spectra. By increasing the concentrations of potassium persulfate, the yields of chitosan nanoparticles also increased. The concentration of potassium persulfate had a significant influence on the production of chitosan nanoparticles. The lowest concentration of potassium persulfate (0.6 mmol) did not produce an observable formation of chitosan nanoparticles. By using formic acid and potassium persulfate in various concentrations from 1.2-3.0 mmol, chitosan nanoparticles were obtained. A particle size distribution of chitosan nanoparticles was produced from a formic acid solution having a smaller size compared to others. The acidity effect of monocarboxylic acids in the formation of chitosan nanoparticles was better compared to the addition of other acids. Furthermore, synthesized chitosan nanoparticles (50-110 nm) produced from formic acid solutions have potential applications for drug carrier purposes.

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