Biodiesel production from theChlorella vulgarisandSpirulina platensismicroalgae by electrolysis using CaO/KOH-Fe3O4and KF/KOH-Fe3O4as magnetic nanocatalysts

Based on the results from recent studies on biodiesel production, in addition to cost reduction, the electrolysis method has both quantitative and qualitative advantages over the reflux method. Thus, in this study, biodiesel was produced by the electrolysis of the oil of two sea microalgae strains, namelyChlorella vulgarisandSpirulina platensis, using methanol and prepared CaO/KOH-Fe(3)O(4)and KF/KOH-Fe(3)O(4)magnetic nanocatalysts. At the first step, magnetic nanocatalysts were prepared, Scanning electron microscope and X-ray diffraction patterns of the prepared nanocatalysts were studied, and the calculated average crystal size of CaO/KOH-Fe(3)O(4)and KF/KOH-Fe(3)O(4)was 55.91 nm and 42 nm, respectively. Brunauer-Emmett-Teller analysis was performed for the determination of the active surface area. Then, two types of mentioned nonfood microalgae were cultured, and the oil of them was extracted. The most suitable microalgae between these two types with regard to the culture condition was chosen for the last step. Then, electrolysis technique contains two graphite plate electrodes (3 cm x 3 cm) that are separated by a distance of 2 cm and potential difference of 54 V with the electrolysis cell which was filled with 100 mL of reaction mixture containing methanol, the aforementioned microalgae oil, Tetrahydrofuran (THF), water, and nanocatalysts was performed for biodiesel production. The effect of catalyst weight percentage (1, 1.5, 2 wt%), molar ratio of alcohol to oil (5:1, 6:1, 7:1), and the reaction time (30, 60, 120, 180 min) in the efficiency of biodiesel production was investigated, and the physical properties of the prepared biodiesel were quantified. Based on the results,Chlorella vulgarismicroalgae because of the more obtainable oil shows the priority of microalgae overSpirulina platensisand KF/KOH-Fe(3)O(4)is an optimal choice catalyst for biodiesel production. The optimal condition was using 1.5 wt% of catalyst, methanol/oil molar ratio of 1:6, temperature of 25 degrees C, stirring speed of 400 rpm, and the reaction time of 2 h. Furthermore, B20 was prepared using the obtained biodiesel, and the quality was in accordance with the world standard of fuel ASTM D975, with the process yield of 96.8%, and no saponification side reaction, and KF/KOH-Fe(3)O(4)showed the higher mass yield in transesterification reaction.

Automated summary

In this study, biodiesel was produced from two sea microalgae strains using the electrolysis method and magnetic nanocatalysts. The effects of different factors on biodiesel production efficiency and quality were investigated, and Chlorella vulgaris microalgae and KF/KOH-Fe(3)O(4) were found to be the optimal choices. The prepared biodiesel met the world standard and showed high process yield.