Synthesis of ZnO nanoparticles by polyol and co-precipitation method and the application for photoesterification of candlenut oil under UV-LED irradiation

Abstract

Zinc oxide nanoparticles (ZnO NPs) were synthesized using the polyol and the coprecipitation method. ZnO NPs were characterized and analyzed by XRD, SEM, UV-DRS, and BET Surface area. The XRD results showed that both synthesis methods have successfully produced ZnO with a hexagonal crystal structure. The results of SEM micrographs show that the ZnO synthesized by coprecipitation method has a particle size around 200-500 nm with a seed-like particle shape and the ZnO synthesized by polyol method has a particle size around 50-100 nm with nanospheres and nanorod particle shape. However, the nanoparticles still undergo agglomeration. The BET analysis results revealed that the surface area of ZnO synthesized by coprecipitation and polyol method was 13.1894 m2/g and 15.5037 m2/g, respectively. The UV-DRS results showed that different synthesis methods generate the same bandgap energy of ZnO which was 3.2 eV for both synthesis methods. The photocatalytic activity of synthesized ZnO NPs was investigated on the application of the photoesterification reaction of candlenut oil in the presence of UV-LED irradiation. The GC-MS results showed that both ZnO polyol and coprecipitation have successfully convert FFA into FAME with %FAME results around 57% and 59% for ZnO coprecipitation and polyol, respectively.