Surface Modification of Poly(vinylidene fluoride) Ultrafiltration Membranes with Chitosan for Anti-Fouling and Antibacterial Performance

Abstract

A graft copolymer (PVDF-g-PAA) having poly(vinylidene fluoride) (PVDF) backbones and poly(acrylic acid) (PAA) side chains was synthesized using the radical polymerization method and the PVDF-g-PAA copolymer membrane was prepared via immersion phase inversion. Then the chitosan was immobilized on the surface of the copolymer membrane by covalent bond. The morphology, surface chemical structure and performance of the modified membranes were characterized by scanning electron microscopy, attenuated total reflection-Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, water contact angle, permeation measurement, antifouling and antibacterial tests. The results showed that the contact angle of the modified membrane decreased, and the water flux increased from 37.74 Lm-2h-1 for pure PVDF membrane to 119.43 Lm-2h-1, which indicated that the modified membrane had higher hydrophilicity than unmodified membrane. The modified membrane has better antifouling properties than pure PVDF membrane due to the increase of surface hydrophilicity, and the highest water flux recovery ratio can achieve 93.2%. Furthermore, the modified membrane showed good antibacterial activity (E. coli), and the maximum antibacterial ratio of the modified membrane was 89.6%.