Fouling behaviours of PVDF-TiO2 mixed-matrix membrane applied to humic acid treatment

Abstract

The aim of this study was to analyses the fouling mechanism of polyvinylidene fluoride-titanium dioxide (PVDF-TiO2) mixed-matrix membranes (MMMs) embedded with three different types of TiO2 nanoparticles (NPs): PC-20, P25, and X500 applied to humic acid (HA) treatment. Although neat membrane has very often been used in a model adapted to cross-flow ultrafiltration (UF), MMM with TiO2 embedment has not been studied before. The identification of fouling mechanisms was determined by four typical modes of Hermia's models and the combined blocking model. The combined blocking model, which involves both cake filtration and pore blocking, taking place at different stages of the membrane filtration process, shows the best correlation with the experimental data. It was shown that the fouling behaviour of the membrane is governed by the nature of the membrane, especially membrane surface roughness. The fine and well dispersed X500 NPs on membrane polymeric matrix were found to have a significant effect on membrane anti-fouling property with a reduced pore blocking parameter, lowest cake layer resistance, and membrane resistance of 0.3261, 2.6201×106/m, and 10.2182×106/m respectively. This finding is attributed to the reduced surface roughness as well as increasing surface energy of X500 MMM.