Green synthesis of calcium oxide nanocatalyst and application in transesterification of waste cooking oil.

This study aims to synthesize calcium oxide nanoparticles by employing green synthetic methods and explore their potential as nano-catalyst based upon the utilization of waste into a value-based product. Waste orange peel extract has been utilized as a reducing medium. The reaction was optimized by varying the reactants' molar ratio to obtain calcium carbonate microparticles that were calcined to obtain calcium oxide nanoparticles with a particle size ranging from 70 to 100 nm. Various spectrochemical techniques analyzed the composition and morphology of the nano-catalyst. The nano-catalyst was further exploited in the one-pot transesterification of waste cooking oil. The biodiesel was analyzed for the presence of methyl ester groups by FTIR and GCMS analysis. The impact of varying reaction constraints, including temperature, contact time, nano-catalyst concentration, and methanol-oil molar ratio, were critically analyzed to optimize biodiesel yield. The study provided an economical and environmentally benign technique to successfully synthesize calcium oxide nano-catalyst to obtain biodiesel with 93.4% yield and effective waste minimization.