Abstract
X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to investigate the structural, surface and particles properties of a series of zinc oxides (ZnO) doped with polyvinyl alcohol (PVA) that were prepared using the sol-gel method. The results demonstrated that the crystallinity of the catalysts decreased as the PVA content increased beyond 5 PVA/ZnO. However, on raising the calcination temperature up to 500 °C, the average crystal size of the PVA/ZnO nanoparticles increased. Next Pyridine adsorption was used to measure the surface acidity of the catalysts, and the results showed that doping ZnO with PVA and raising the calcination temperature to 500 °C increased the catalyst's surface acidity. Furthermore, the data indicates that raising the ratio of the Brønsted to Lewis acid sites enhanced the catalytic activity for the synthesis of coumarin derivatives. We concluded that the structural and acidity characteristics of the catalysts under study had a significant impact on the catalytic activity. Furthermore, a study examining the biological activity of ZnO/PVA and pure ZnO revealed that 5PVA/ZnO performed the best in terms of improving the kidney functions of diabetic rats.