Improving the hydrophilicity of the poly(vinylidene fluoride) (PVDF) ultrafiltration membrane can change its adsorption fouling characteristics. Here, a novel amphiphilic material of PVDF grafted with N-methylolacrylamide (PVDF-g-NMA) was developed via photoinduced Cu(II)-mediated reversible deactivation radical polymerization (RDRP). The PVDF-g-NMA ultrafiltration membrane was prepared by the nonsolvent-induced phase-separation method. The PVDF-g-NMA copolymer was characterized by 1H NMR and Fourier transform infrared spectroscopy. The performance of the PVDF-g-NMA membrane was evaluated by determining the permeation flux, contact angle, roughness, and antifouling tests. The roughness data show that a low content of N-methylolacrylamide can effectively reduce the surface roughness of membranes by 50%, resulting in greater antifouling ability. The prepared ultrafiltration membrane containing 15 wt % PVDF-g-NMA exhibited the best hydrophilicity with an average pure water flux of up to 272.1 L·m–2·h–1, higher than that of the pure PVDF membrane (45.4 L·m–2·h–1). The contact angle of the PVDF-g-NMA ultrafiltration membrane decreased from 85.5 to 67.4°. The bovine serum albumin rejection rate of the PVDF-g-NMA membrane significantly increased from 85.7 to 92.6%, and the pure water flux recovery rate increased from 79.0 to 88.5%. The PVDF-g-NMA ultrafiltration membrane had excellent hydrophilicity and antifouling properties, which would be promising for wastewater treatment.
Xiaolong Zhang,Haowen Zhuang,Chenxuan Shao,Chen Wang,Xiaohui Ju,Qi Zhang,Yujia Tong,Weixing Li
Although membrane separation technology has been widely used for oily wastewater treatment in recent years, surface fouling still poses a great threat to application. Due to the strong adsorption of oil droplets onto membrane surface and within pores, pristine membranes are inadequate for long-term oil-water separation applications. Here, a novel photocatalytic nanofiber membrane via microchip grafting with in-situ mineralization was proposed. N-Methylolacrylamide (NMA) was successfully grafted on polyvinylidene fluoride (PVDF) by microfluidic electrospinning, and the grafting amount was 9 times that under conventional bottle reaction conditions. The in-situ mineralization time via the polyphenol-metal network was reduced from 27 h to 18 h, while the mineralization rate increased by threefold compared with the bottle-grafted membrane. For oil-water emulsion separation, the developed PVDF-g-NMA@FeOOH membrane successfully showed the high permeability of 38870 L·m −2 ·h −1 ·bar −1 with the outstanding rejection rate of 99.2%. It displayed great photocatalytic self-cleaning performance, and the flux recovery rate was up to 95.8% after cycle tests. Methhyllene blue (MB) removal rate reached 96.3% in 50 min. The developed membrane holds great promise for applications in oil-water separation and organic contaminant degradation.
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