Electricity-assisted antifouling ceramic membrane modified by Magnéli titanium sub-oxides for environmental and biological applications

Membrane fouling is a fatal disadvantage hindering the application of membrane separation technology, which decreases permeate flux and shortens membrane service life. This research aims to solve this problem by combining membrane separation technology with external electricity through electrophoretic or electro-oxidation effect. The Magnéli titanium sub-oxide Ti4O7, with robust physical properties and high electrical conductivity, was employed to modify the Al2O3 ceramic membrane to make a novel composite material. The Ti4O7 phase was obtained by dip-coating a TiO2 layer followed by chemical reduction at 1050℃ in H2 atmosphere. The fabricated Ti4O7 layer exhibited a conductivity of over 200 S·cm-1 with particle size of 200 - 300 nm, average pore diameter of 350 nm and water contact angle of 0°. The antifouling performance of the prepared tubular Ti4O7/Al2O3 membrane was evaluated through a home-made cross-flow electricity-assisted membrane filtration (EAF) module where the prepared membrane element served as both the electrode(s) and the filtration media. Two types of electrode configurations were explored for the design of EAF module, namely membrane-wire and membrane-membrane electrode configurations. For the former configuration, electricity was connected between the inner Ti4O7 layer and a wire electrode. For the latter, the inner and outer modified Ti4O7 layers served as electrodes. The filtration performance using the designed EAF module was first evaluated for the treatment of emulsified oily wastewater. The system was further examined using two other typical feed solutions that are known to foul easily, humic acid (HA) and whey proteins. It was found out that the membrane-wire electrode configuration was more effective, especially when electrophoresis