Alumina double-layered ultrafiltration membranes with enhanced water flux

In the present work, γ-alumina double-layered ultrafiltration (UF) membranes with novel gradient pore-sized active layers and single-layered UF membranes were produced using an approach of tightening the pore size of alumina microfiltration (MF) membranes. With the processes of sol-gel, dip coating and sintering, the achieved single- and double-layered UF membranes displayed similar performance in particle size retention, and the double-layered membrane expressed better properties than the single-layered UF membrane in terms of water flux, resistance and anti-fouling. Compared to the MF membrane, the prepared UF membranes displayed improved hydrophilicity and enhanced particle size retention behavior, but lower flux, higher resistance and weaker anti-fouling performance. However, the UF membrane with double layers exhibited values of flux and resistance in the same order of magnitude as those of the MF membrane. The produced alumina double-layered membranes with enhanced flux are of great potential in UF of water.