Effect of hydrophilic modification with nano-titania and operation modes on the oil–water separation performance of microfiltration membrane

Abstract

The tubular Al₂O₃ microfiltration membranes modified with nano-TiO₂ coating were applied in the separation of waste oil-in-water emulsion. The separation performances of the MF membranes with and without nano-TiO₂ modification were studied under two different operation modes, i.e. the circulation mode and the concentration mode, respectively. The circulation mode in which the oil concentration in feed keeps constant simulates the condition of the great amount of feed to be treated, while the concentration mode in which the oil concentration in feed increases with the extraction of the filtrate simulates the condition of a small amount of feed to be treated. The results show that the operation mode has a less effect on the flux of the MF membranes, but has an important effect on the oil concentration of filtrate for the unmodified membrane. The oil concentration in filtrate under concentration mode is higher than that of circulation mode. For the modified membrane, the operation mode has a less effect on the flux and the oil concentration of filtrate, because the hydrophilic nano-TiO₂ coating prevents oil droplets from penetrating the membrane pores. Under both operation modes, the fluxes of the modified membranes are higher than those of the unmodified membranes.

Keywords:

• Microfiltration membrane
• Membrane modification
• Oil-in-water separation
• Operation mode
• Membrane fouling

Acknowledgments

The authors gratefully acknowledge the financial support provided by Sino-French International Science and Technology Cooperation Program (No. 2011DFA52000), by National Natural Science Foundation of China (Nos. 51062006 and 51262012), and by Natural Science Foundation of Jiangxi Province (Nos. 20114BAB213012, 2011BAB206022, and 2013ACB20007).