Functional surface modification of PVDF membrane for chemical pulse cleaning

Membrane fouling research has become a focus, significant amount of work has been dedicated to membrane surface modification for improving anti-fouling performance. However, fouling still occurs, which means cleaning is inevitable. The present method is mainly inefficient offline chemical cleaning using specialized chemicals. So we put forward a new method of online chemical pulse cleaning accomplished by designing a kind of pH responsive molecular structure on the PVDF membrane surface, which was prepared through wet chemical strategy, under basic conditions, by using diethylenetriamine (DETA) as carrier of amino groups, and then these amino groups were activated with maleic anhydride (MAH) in order to introduce carboxyl groups. The modified membranes were characterized by attenuated total reflectance-Fourier transform infrared spectra (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), mechanical property, streaming potential and contact angle measurements. The results of water flux and swelling degree revealed the flexible chains had excellent pH responsive. And the modified membranes showed outstanding anti-pollution capability and online chemical pulse cleaning effect when used to separate soybean oil-in-water emulsion and BSA solution. Meanwhile, the flux recovery rates after five times circulation could still reach 90.3% and 95.2%, respectively. This study provides a new way for building antifouling surface and improving cleaning efficiency.