Novel PVDF hollow fiber ultrafiltration membranes with antibacterial and antifouling properties by embedding N-halamine functionalized multi-walled carbon nanotubes (MWNTs)

Abstract

Multi-walled carbon nanotubes grafted with (3-chloro-2-hydroxypropyl)-(5,5-dimethylhydantoinyl-1-ylmethyl)-dimethylammonium chloride (MWNTs-g-CDDAC) are doped in a PVDF spinning solution to prepare a kind of novel PVDF/MWNTs-g-CDDAC hollow fiber ultrafiltration membrane with antibacterial and antifouling properties. The MWNTs-g-CDDAC are firstly synthesized and characterized by FTIR, XPS and TGA. With the addition of MWNTs-g-CDDAC in the dopes, the sponge-like structure is suppressed and the finger-like macrovoids grow wider for the PVDF/MWNTs-g-CDDAC hollow fiber membranes. The surface hydrophilicity and antifouling ability of the membranes are evidently improved by introducing MWNTs-g-CDDAC onto the membranes. The pure water permeability gradually increases with the loading of MWNTs-g-CDDAC in the hybrid membranes, and the highest value of 94.7 L m⁻² bar⁻¹ h⁻¹ is obtained with 0.5 wt% MWNTs-g-CDDAC addition in the dope. The permeation flux recovery ratio (R_f) increases with the addition of MWNTs-g-CDDAC, and M-75 (0.75 wt% MWNTs-g-CDDAC loading in dope) exhibits the highest R_f value of 90.6% after two ultrafiltration-cleaning cycles for a BSA aqueous solution. The fabricated PVDF/MWNTs-g-CDDAC membranes have favorable antibacterial efficacy, and M-75 shows the utmost sterilization ratios of 92.7% and 95.2% against E. coli and S. aureus, respectively.