Fabrication and characterization of hierarchically macroporous Al2O3 ceramic supported ZnO/ZnS photocatalyst

Abstract

Hierarchically macroporous Al2O3 ceramic carriers were prepared by direct-foaming combined gel-freezing method. ZnO/ZnS photocatalyst was loaded on the porous carrier through hydrothermal method. The effects of solid content, polyvinyl alcohol content, stirring speed, and sintering temperature on the pore structure, porosity, and compressive strength of the porous carrier were investigated. The pore forming mechanism was also studied. The morphology of ZnO/ZnS photocatalyst was adjusted by changing the pH value during hydrothermal process. The results show that the porous ceramic contains four different sizes of pores, spherical pore, through pore, unidirectional pore, and interstitial pore. The pore structure and strength can be regulated through optimizing process parameters. The porosity and compressive strength of porous carrier prepared with 1.2 % PVA content, 22 % solid content, 1500 r/min stirring speed and 1500 °C sintering temperature are 89.4 % and 1.45 MPa, respectively, which is suitable to be used as the photocatalyst carrier. When the pH value is 10, the size and distribution of ZnO/ZnS photocatalyst are matched with the pore structure of porous carrier. The supported ZnO/ZnS has high photocatalytic activity and good reusability.