Biodiesel production of avocado seed oils has been carried out using the heterogeneous catalyst of Mg-Al/hydrotalcite. Transesterification process was conducted by varying temperature reaction and oil-methanol molar ratio. The reaction temperature was 30, 40, 50, and 60°C, whereas the oil-methanol molar ratio was 1:3, 1:6, 1:9, and 1:12, respectively. As-synthesized Mg-Al/hydrotalcite catalyst was characterized using X-ray diffraction and FTIR. Meanwhile, the biodiesel was analyzed their density, viscosity, water content and 1H-NMR analysis. The results showed that optimum condition in biodiesel production was oil-methanol molar ratio of 1:6 at a reaction temperature of 60°C for 60 minutes and catalyst quantity of 2% yielding biodiesel conversion percentage was approximately 15.90%. However, this preliminary findings showed that Mg-Al/hydrotalcite was able to convert the avocado seed oils into biodiesel even if still need further analysis and research so that produces a higher percentage of biodiesel conversion.

The highly active photocatalyst of Ag3PO4 could be synthesized under ammonia solution using the facile co-precipitation method with the starting material of AgNO3 and Na2HPO4.12H2O. The variation of ammonia concentration was designed at 0.00, 0.05, 0.15, and 0.30 M. The products were characterized using X-ray diffraction, UV-diffuse reflectance spectroscopy, and scanning electron microscopy. The photocatalytic activities were evaluated using the Rhodamine B degradation under blue light irradiation. The effect of calcination, pH condition, and visible light source irradiation was carried out in the experiment. The highest photocatalytic activity was found in the sample prepared using the addition of ammonia solution at the concentration of 0.05 M. This photocatalytic activity was 4.13 times higher compared to the Ag3PO4 prepared without the ammonia. The effective condition of photocatalytic activity was achieved at the sample prepared without calcination, degradation at pH of 7 and under blue light irradiation. dye removal. Silver orthophosphate has the band gap energy of 2.36 eV, that can absorb solar energy shorter than ~530 nm [1-6], possess stronger photo-oxidative capability than the previous photocatalyst [7-9], generating O2 from water splitting with a quantum efficiency nearly 90% in visible light irradiation [10]. In order to improve its photocatalytic activity in the visible light region, many approaches have been performed especially in catalyst fabrication design

Microbial fuel cell (MFC) merupakan suatu teknologi yang memanfaatkan mikroba untuk mendegradasi bahan organik dan anorganik menjadi energi listrik, dapat dilakukan menggunakan sistem satu bejana atau dua bejana. Sistem MFC dua bejana menggunakan membran penukar proton yang berfungsi untuk mengalirkan proton yang dihasilkan dari ruang anoda ke ruang katoda, salah satu alternatif membran yang digunakan yaitu komposit kitosan-karagenan. Penelitian ini bertujuan untuk menentukan perbandingan komposit kitosan-karagenan sebagai membran penukar proton pada MFC, menentukan kinerja MFC dalam menghasilkan elektrisitas, serta menentukan kinerja penurunan beban polutan limbah cair pada MFC. Nilai elektrisitas MFC diukur menggunakan multimeter dengan parameter yang diuji adalah tegangan listrik, serta arus listrik. Parameter uji yang digunakan untuk mengukur penurunan beban polutan limbah cair adalah chemical oxygen demand (COD), biologycal oxygen demand (BOD) dan total amonia nitrogen (TAN). Membran komposit kitosan-karagenan dibuat dengan perlakuan perbedaan komposisi kitosan dan karagenan 1:1; 1,5:1; 3:1 (v/v). Perbedaan rasio kitosan dan karagenan pada membran komposit kitosan-karagenan memberikan pengaruh terhadap sifat mekanik membran, nilai elektrisitas MFC, serta beban polutan cair pada MFC. Membran komposit kitosan-karagenan dengan perbandingan 1:1 menghasilkan nilai konduktivitas proton tertinggi sebesar 1,15x10-3 S/cm, kuat tarik tertinggi 7,047 MPa, tegangan listrik 0,97 V, arus 7,02 mA, serta daya listrik 6,84 mW. Nilai COD, BOD, serta TAN limbah cair pemindangan ikan mengalami penurunan sebesar 90%, 76% dan 32%.