Effect of the Peptization Process and Thermal Treatment on the Sol-Gel Preparation of Mesoporous α-Alumina Membranes

Compared to traditional membrane materials, alumina membranes are particularly beneficial for industrial wastewater treatment. However, the development of mesoporous alpha-alumina membranes for ultrafiltration applications is still a challenge due to uncontrolled pore size. In this study, we optimized the sol-gel method for the fabrication of a high-performance mesoporous alpha-alumina membrane. The peptization conditions (pH and peptization time) and phase transformation of boehmite were investigated to achieve better properties of the alpha-alumina membrane. The surface properties of the membrane were observed to be improved by reducing the system pH to 3.5 and increasing the peptization time to 24 h. The effect of sintering temperature on the phase transformation behavior, microstructures and performance of the membranes was also elucidated. An alpha-alumina ultrafiltration membrane with an average thickness of 2 mu m was obtained after sintering at 1100 degrees C. The molecular weight cut-off of the alpha-alumina membrane, as obtained by the filtration of aqueous PEG solution, was approximately 163 kDa (12.5 nm). This is the smallest pore size ever reported for pure alpha-alumina membranes.

Automated summary

In this study, a high-performance mesoporous alpha-alumina membrane was successfully fabricated using the sol-gel method. The surface properties of the membrane were improved and the membrane achieved the smallest reported pore size for pure alpha-alumina membranes.