Double-side active TiO2-modified nanofiltration membranes in continuous flow photocatalytic reactors for effective water purification

A chemical vapour deposition (CVD) based innovative approach was applied with the purpose to develop composite TiO2 photocatalytic nanofiltration (NF) membranes. The method involved pyrolytic decomposition of titanium tetraisopropoxide (TTIP) vapor and formation of TiO2 nanoparticles through homogeneous gas phase reactions and aggregation of the produced intermediate species. The grown nanoparticles diffused and deposited on the surface of gamma-alumina NF membrane tubes. The CVD reactor allowed for online monitoring of the carrier gas permeability during the treatment, providing a first insight on the pore efficiency and thickness of the formed photocatalytic layers. In addition, the thin TiO2 deposits were developed on both membrane sides without sacrificing the high yield rates. Important innovation was also introduced in what concerns the photocatalytic performance evaluation. The membrane efficiency to photo degrade typical water pollutants, was evaluated in a continuous flow water purification device, applying UV irradiation on both membrane sides. The developed composite NF membranes were highly efficient in the decomposition of methyl orange exhibiting low adsorption-fouling tendency and high water permeability. (c) 2011 Elsevier B.V. All rights reserved.