Controlling pore size and its distribution of γ-Al2O3 nanofiltration membranes

The preparation process of gamma-Al2O3 nanofiltration membranes were studied by N-2 absorption and desorption test and retention rate vs thickness gradient curve method. It was found that template and thermal treatment were key factors for controlling pore size and its distribution. Under the optimized experimental conditions, the BJH (Barret-Joyner-Halenda) desorption average pore diameter, BJH desorption cumulative volume of pores and BET (Brunauer-Emmett-Teller) surface area of obtained membranes were about 3.9 nm, 0.33 cm(3)/g and 245 m(2)/g respectively, the pore size distribution was very narrow. Pore size decreased with the increasing of thickness and no evident change after the dense top layer was formed. The optimum thickness can be controlled by retention rate vs thickness gradient curve method.