Abstract:

Poly(styrene sulfonic acid)-graft-poly(vinylidene fluoride)(PSSA-g-PVDF) membrane was prepared via phase bulk modification with tetramethylammonium hydroxide(TMAH), grafting styrene sulfonic acid(SSA) onto PVDF with benzoyl peroxide(BPO) as an initiator. After that, the copolymer was casted into a flat membrane via immersion phase inversion. It was investigated that TMAH content has effect on grafting degree(GD) and the oil/water separation membrane performance of PSSA. At the same time, Fourier transform infrared spectrum(FTIR), scanning electron microscope(SEM) and video optical contact angle measuring test were adopted to measure the membrane structure and surface contact angle. The results showed that the partial HF was eliminated from PVDF by TMAH forming carbon double bonds and styrene sulfonic acid was grafted onto the modified PVDF skeletons. The GD of PSSA-g-PVDF membrane increased as more TMAH used. The optimized hydrophilicity of modified PVDF membrane was obtained with 20% of TMAH, when the GD of membrane was 22.1%. The contact angle of the separation membrane was reduced to 37.2° within 30 s. Water flux was 643.3 L/(m·h). Rejection rate was 90.6% and the water flux recovery rate was 93.7%. The attenuation rate was 7.1%. The cycle test showed that the water flux recovery rate and oil-water flux recovery rate of the membrane were both above 90%.

Key words: oil/water separation membrane, one-step, tetramethylammonium hydroxide, poly(vinylidene fluoride), styrene sulfonic acid