Sulfonic nanohydrogelled surface-modified microporous polyvinylidene fluoride membrane with excellent antifouling performance for treating water-oil separation of kitchen wastewater

Abstract

Kitchen wastewater containing high concentration of suspended solids, salt and oil is a comprehensive wastewater that requires urgent treatment. Organic fouling limits the use of membranes for treating kitchen wastewater. Herein, we propose a novel sulfonic nanohydrogel membrane with superhydrophilicity and underwater-superoleophobicity. A 32-nm-diameter sulfonic nanohydrogel Poly(SPP-co-MA-co-FLUORAL-P), developed by the polymerization technique in an aqueous medium, was grafted onto the polyvinylidene difluoride (PVDF) microfiltration membranes. The developed PVDF-g-Poly(SPP-co-MA-co-FLUORAL-P) membrane exhibited excellent antifouling properties for treating kitchen wastewater. The influence of organics (edible oil, surfactant, protein and humic acid) and salts on the membrane filtration was thoroughly investigated. The Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy techniques were used to confirm the successful surface modification. The experimental results revealed that the pure water flux was 2161 L m−2 h−1. A high oil rejection rate was achieved when the fabricated membrane was used for treating the simulated kitchen wastewater (˃99.7%). The excellent antifouling properties of the membrane significantly improved the circulation stability of the simulated kitchen wastewater filtration. The recovery rate of permeation flux was up to 100%. The chemical oxygen demand removal rate of the real kitchen wastewater was 61% and the flux recovery rate arrived at 98%. The PVDF-g-Poly(SPP-co-MA-co-FLUORAL-P) membrane can be potentially used for treating kitchen wastewater.