Dynamically coated photocatalytic zeolite–TiO2 membrane for oil-in-water emulsion separation

Abstract

This paper evaluated the effectiveness of polyester (PS)/poly(vinyl alcohol) (PVA) dynamic membrane (DM) incorporating photocatalytic zeolite/TiO2 for oil-in-water (O/W) emulsion separation. The photocatalytic zeolite/TiO2 was established onto the membrane surface via self-forming and pre-coating method with the aims of reducing membrane fouling during O/W emulsion treatment. The results obtained showed that the pre-coated composite DM could decrease support membrane fouling by improving flux recovery rate by 5.8%, while the use of the self-forming composite DM exhibited lower flux recovery rate after three filtration cycles in O/W emulsion treatment. The results were confirmed by cleaning and oil removal efficiency. The cleaning efficiency of composite DM was further enhanced by substitution of deionized water with sodium dodecyl sulfate as a cleaning agent in the treatment of O/W emulsion. Using sodium dodecyl sulfate, the pre-coated composite DM showed higher flux recovery rate (81%) than the self-forming composite DM. In addition, the photocatalytic effects of zeolite/TiO2 on the DM with respect to flux recovery rate and oil rejection under UV light source were investigated. It was found that by combining cleaning process and UV irradiation, the fouling of DM was further decreased, recording high flux recovery rate (up to 83.6%) without compromising oil rejection rate (85.3%).