Highly active and recyclable CuO/ZnO as photocatalyst for transesterification of waste cooking oil to biodiesel and the kinetics

Since people have a strong interest in the potential replacement of fossil fuels by renewable energy biodiesel, this study uses low-cost waste cooking oil as raw materials and CuO/ZnO photocatalyst transesterification to prepare biodiesel. In this experiment, the precipitation method was used to prepare CuO/ZnO photocatalyst. The XRD, HR-TEM, SEM-EDS, BET, UV-Vis, and Raman spectra were all used to characterize the morphology, functional groups, and photocatalytic activity of the photocatalyst. The optimal reaction conditions were 5 wt% catalyst dosage with 9:1 molar of ethanol to waste cooking oil at 65 degrees C for 2 h, the yield of biodiesel was 93.5%. In the sixth cycle experiment, the yield of biodiesel can still reach more than 80%, which proves that the catalyst has strong activity and stable operability. At the same time, the reaction mechanism and kinetics of the experiment were explored. After comparing with the standard database (GB/T 20828-2015 and ASTM D6751), the biodiesel produced by this designed process conforms to the standard specifications. This research has proposed an efficient and green biodiesel preparation method, which uses waste cooking oil as raw material to achieve realizable waste utilization and reduce production costs. At the same time, a novel, stable and reusable photocatalyst was prepared as well, which opened up a new way for the production of biodiesel.

Automated summary

This study uses low-cost waste cooking oil and CuO/ZnO photocatalyst transesterification to prepare biodiesel. The optimal reaction conditions were determined and the reaction mechanism and kinetics were explored. The biodiesel produced by this method conforms to standard specifications, achieving waste utilization and cost reduction.