Fabrication and modification of PVDF membrane by PDA@ZnO for enhancing hydrophilic and antifouling property

There is an urgent need for an antifouling membrane to treat the large volume of dye-containing wastewater generated annually by the dyeing and printing industry. PDA@ZnO/PVDF membranes were synthesized by doping polydopamine (PDA) and zinc oxide (ZnO) nanoparticles into the polyvinylidene fluoride (PVDF) membranes via non-solvent induced phase separation (NIPS) method in which polyvinylpyrrolidone (PVP) and lithium chloride (LiCl) were chosen as the porogens respectively. Their microstructures were characterized, and the membranes were examined for antifouling properties and membrane separation performance. The presence of PDA@ZnO nanoparticles on the PVDF membrane was evidenced by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) measurements. The addition of PDA@ZnO enhanced the mechanical strength and hydrophilicity of the nanocomposite membranes. The PVDF membranes' water permeability and antifouling properties improved following mixing modification, according to the dye filtration test. The pure water flux of PDA@ZnO/PVDF hybrid membranes changed from 260.0 L·m-2·h-1·bar-1 to 1339.2 L·m-2·h-1·bar-1 by varying the concentration of PDA@ZnO nanoparticles from 0 wt% to 1.6 wt%. The retention performance of the modified membranes was shown to be significantly superior to the pure PVDF membrane. The modified membranes with the addition of 2.0 wt% LiCl and 1.2 wt% PDA@ZnO nanoparticles had highly disperse blue 79 (DB 79) retentions (90.5%) and pure water flux (379.2 L·m-2·h-1·bar-1), indicating that the modified membrane possessed the characteristics of a promising membrane for the purification of dye. Tests found that PDA@ZnO significantly improved the membrane's antifouling performance.