Synthesis and catalytic properties of calcium oxide obtained from organic ash over a titanium nanocatalyst for biodiesel production from dairy scum

The fatty acid methyl ester (FAME) production from dairy effluent scum as a sustainable energy source using CaO obtained from organic ash over titanium dioxide nanoparticles (TNPs) as the transesterification nano-catalyst has been studied. The physical and chemical properties of the synthesized catalysts were characterized, and the effect of different experimental factors on the biodiesel yield was studied. It was revealed that the CaO–TiO₂ nano-catalyst displayed bifunctional properties, has both basic and acid phases, and leads to various effects on the catalyst activity in the transesterification process. These bifunctional properties are critical for achieving simultaneous transesterification of dairy scum oil feedstock. According to the reaction results, the catalyst without and with a low ratio of TNPs showed a low catalytic activity. In contrast, the 3Ca–3Ti nano-catalyst had the highest catalytic activity and a strong potential for reusability, producing a maximum biodiesel yield of 97.2% for a 3 wt% catalyst, 1:20 oil to methanol molar ratio for the dairy scum, and a reaction temperature of 70 °C for a period of 120 min under a 300 kPa pressure. The physical properties of the produced biodiesel are within the EN14214 standards.