Biodiesel synthesis via metal oxides and metal chlorides catalysis from marine alga Melanothamnus afaqhusainii

Abstract This research article demonstrates the most comprehensive comparative catalytic study of different metal oxides and metal chlorides towards the methanolysis of triglycerides of marine red macroalga Melanothamnus afaqhusainii . CaO was found to be the most reactive metal oxide that yielded 80% biodiesel while ZnCl 2 was the most reactive metal chloride that produced 60% biodiesel by mechanical stirring for 6 h at 100–110 °C. The overall reactivity order of the catalysts was found to be CaO > MgO > PbO 2  > ZnCl 2  > TiCl 4  > PbO > HgCl 2  > ZnO > AlCl 3  > SnCl 2  > TiO 2 whereas, CaCl 2 , MgCl 2 , Al 2 O 3 , HgO, PbCl 2 , MnO 2 , MnCl 2 , Fe 2 O 3 and FeCl 3 were found to be non-reactive for transesterification of triglycerides. In addition, a detailed study of the screening of mobile phases and spraying reagents was conducted which showed that petroleum ether : chloroform : toluene (7:2:1) is the best mobile phase, whereas iodine crystals/silica gel is the best visualizing agent for the thin layer chromatography (TLC) examination of biodiesel. Biodiesel production was confirmed by comparative TLC examination. It was further supported by the determination of fuel properties of biodiesel, which were found to be similar to the standard limits of American Society for Testing and Materials (ASTM).