Fabrication of nanoporous aluminum-oxide composite membranes

To overcome the poor mechanical property of anodic aluminum-oxide (AAO) membranes, we tried to develop AAO/Al composite membranes consisting of membrane cells with straight-pore channels of 40 to 100 nm in diameter and a mesh-like pattern acting as a supporting layer by using UV-light lithography followed by wet-etching for the formation of a mesh-like pattern and anodic oxidation followed by wet-etching for the formation of nano-pores with desired specifications. As a result, AAO/Al composite membranes with breaking pressures of over 5 bar, which is an upper bound for ultra- and micro-filtration, could be fabricated. An AAO/Al composite membrane with a water permeability as high as 130 L/m2·h·bar could be fabricated. The composite membranes developed in the present study can be used in micro- and ultra-filtration of severe environments with relatively high economic efficiency and large margins in the flow rate and the breaking pressure.