Biodiesel from microalgae Nannochloropsis oculata and Tetraselmis chuii by sonication technique and K2CO3 catalyst

The way out of the energy crisis is to divert national energy needs with the use of new and renewable energy. Bioenergy such as biodiesel is the expected one of those. Algae which has the potential to be used as raw material for making biodiesel is microalgae because it is easier in its cultivation. The microalgae used in this study were Nannochloropsis oculata and Tetraselmis chuii . Microalgae that have been harvested in the pasta form are extracted to obtain the oil then processed into biodiesel with an ultrasonic device. The transesterification reaction ran at 65 o C with a 1% K 2 CO 3 catalyst. The variables applied were the ratio of oil: methanol (1:5; 1:10; 1:15) and reaction time (1 and 3 hours). The biodiesel produced was then tested for acid numbers, %FFA, density, viscosity, and GC-MS analysis. The amount of N. oculata and T. chuii obtained from harvesting was 591.75 and 460.11 grams, respectively. The yield of oil extracted from N. oculata and T. chuii was 46.47% and 39.31%. Biodiesel yield obtained from N. oculata between 72.19-74.33% with the highest yield for N3 sample, meanwhile in T. chuii between 69-72.95% with the highest gain for T3 sample. In general, biodiesel samples meet national standard SNI for Biodiesel in density, viscosity and acid number. The methyl ester content of the GC-MS test in the best biodiesel samples is N1 sample at 68.4% and T6 sample at 79.49%.