Inorganic mesoporous membranes showed potential for water purification and desalinization by nanofiltration.
In this work, a composite mesoporous inorganic membrane was synthesized with a two layer structure. The supporting layer was a macroporous α-Al2O3 substrate prepared with the colloidal filtration technique. The functional layer was a mesoporous γ-alumina thin film prepared with the sol-gel method. The synthesis of each layer was systematically studied and carefully optimized to obtain defect free membranes.
The membrane device was then tested with a homemade water pressurization chamber under various experimental conditions to systematically characterize the water purification performance of the membrane. The experiments determined limiting salt rejection at various testing conditions. The purification behavior was studied for three types of electrolyte aqueous solutions, NaCl, CaCl2 and AlCl3 at a concentration range from 0.001 M to 0.1 M.
A model based on surface charge adsorption and electrokinetic mass transportation was established with commercial FEM modeling software, COMSOL 3.2b, to study the purification mechanism and the performance limitations. Qualitative agreement between the experiment and the modeling results was obtained.