Effect of the surface properties on filtration performance of Al₂O₃-TiO₂ composite membrane

Knowledge of the surface properties of ceramic membranes is useful for understanding and predicting their filtration performance. In this study focus was put on investigation of the effect of membrane surface properties on filtration performance. The TiO₂-doped Al₂O₃ composite microfiltration membrane with an average pore size of 0.2 μm was prepared by solid state sintering method. The surface wettability and surface charge properties of porous ceramic membrane were determined by measurement of the dynamic contact angle and streaming potential. The results indicate the TiO₂ doping improves membrane hydrophilicity and makes the isoelectric point shift towards lower pH. The Al₂O₃ and Al₂O₃-TiO₂ membrane were applied to separate oily wastewater to evaluate the filtration performance. The interactions between the membrane surface and oil droplets strongly influence the formation of membrane fouling. A higher and more stable permeate flux was observed through the Al₂O₃-TiO₂ composite membrane, which demonstrated that in the filtration of oily wastewater enhancing membrane hydrophilicity and having the same type of charge as the oil droplets can improve the membrane filtration performance.