Study on the effect of modified PVDF ultrafiltration membrane for secondary effluent of urban sewage

Abstract

The cross-linked poly(vinyl alcohol) (PVA)/poly(vinylidene fluoride) composite flat sheet membranes were successfully prepared by phase inversion method. Ferric trichloride (FeCl₃) particles were used as cross-linker. PVA is cross-linked during the membrane fabrication. The structures of formed membranes were investigated using scanning electron microscopy and Fourier transform infrared spectroscopy (FTIR). The hydrophilic contact angle, pure water flux, and tensile strength were measured to assess the membrane performance. The antifouling performance of modified membrane for the secondary effluent of urban sewage was evaluated by flux decline, washing recovery rate, fouling resistance analysis, and fractions distribution of different hydrophilicities. FTIR showed that the peak intensity, attributed to –OH groups, decrease gradually with the increase of FeCl₃, indicating the formation of a PVA–Fe³⁺ net work structure. The addition of cross-linking agent FeCl₃ confined the compaction of membranes, thus the fouling resistances of membranes were lower and the water flux was higher. When the weight ratio of PVA to FeCl₃ was 1/0.09, the modified membranes had the best UF performance and antifouling property.

Keywords:

• Antifouling
• Cross-linking
• Ultrafiltration
• Hydrophilic modification
• Secondary effluent

Acknowledgments

This research was financially supported by the National Natural Science Foundation of China (Grant No. 51008243, No. 51178378, No. 51278408); Shanxi Province technology and science innovation project (Grant No. 2012KTCL03-06) and the Fund of Shann’xi Educational Committee (2013JK0884).