CB[6]/ZnO chelated superoleophobic-hydrophilic PVDF membranes for one-step remediation of multi-contaminant in wastewater

Abstract

Industrial wastewater, despite undergoing primary and secondary treatments with conventional methods, continues to pose challenges due to the presence of multiple contaminants. Membrane separation has emerged as an effective solution to streamline the treatment process, yet it often results in surface fouling. This study introduces a single platform designed for simultaneous removal of dyes, oils, and proteins during the tertiary treatment stage, thereby eliminating the need for multiple separation steps. To enhance membrane robustness and address common fouling issues, polyvinylidene fluoride-montmorillonite-cucurbit[6]uril/zinc oxide (PV-M-CB[6]ZnO) mixed-matrix membranes have been developed. The incorporation of montmorillonite (M), cucurbit[6]uril (CB[6]) host-guest encapsulation, and zinc metal chelation significantly improves the membrane's capability in eliminating cationic dyes, treating oil-water emulsions, and separating bovine serum albumin. With an optimal CB[6]/ZnO loading of 1.6 wt%, the PV-M-CB[6]ZnO membranes exhibit superior performance with high water permeability (4114 L/m².h.bar) and exceptional separation efficiencies: 95.5% for malachite green, 93.2% for methylene blue, and 98.2% for crystal violet, compared to pristine PVDF membranes. Additionally, these membranes demonstrate an impressive oil-water rejection rate of 97.6% and a bovine serum albumin rejection rate of 76%, with a flux recovery ratio exceeding 86% after seven filtration cycles. Thus, the PV-M-CB[6]ZnO membranes offer enhanced hydrophilicity, improved antifouling properties, and increased efficiency for the removal of multiple contaminants from industrial wastewater, providing a promising solution for sustainable environmental remediation.