Fabrication of ZIF-67@PVDF ultrafiltration membrane with improved antifouling and separation performance for dye wastewater treatment via sulfate radical enhancement

Abstract

• PVDF ultrafiltration membranes were prepared using pristine ZIF-67 nanoparticles. • ZIF-67 were exhibited excellent catalytic activity in the PVDF membrane. • Utilizing ROS generated from PMS-activated ZIF-67@PVDF to enhance dye removal. • The flux/ FRR of the ZIF-67@PVDF-1.0 membrane were 4.25/2 times that of PVDF. • On-line cleaning achieved an average AO7 maximum removal of 98.9% within pH = 11.0. Efficient separation and excellent antifouling performance of ultrafiltration (UF) membrane are highly desirable for sustainable wastewater treatment. This work reports a novel ZIF-67-imbedded PVDF (ZIF-67@PVDF) mixed-matrix UF membrane fabricated by nonsolvent-induced phase separation (NIPS) technique to reinforce efficient removal of dye wastewater via sulfate radical enhancement. The imbedded ZIF-67 well-dispersed within the membrane improved the membrane pore structure and benefited peroxymonosulfate (PMS) activation to generate sulfate radical that were confirmed by Electron spin resonance (ESR) spectroscopy. As a synergistic effect of pore structure and sulfate radical generation, the separation, antifouling and catalytic performance of the ZIF-67@PVDF membranes were greatly enhanced over a wide pH range. Even at a high pH of 11, the PMS on-line cleaning assisted ZIF-67@PVDF-1.0 membrane achieved high dye removal efficiency for orange Ⅱ (AO7, 97.3%), Methylene blue (98.2%), Rhodamine B (90.5%). The ZIF-67@PVDF membrane also showed good reusability and stability. This work demonstrates great potential of using self-cleaning UF membranes to treat dye wastewater.