Gallic acid functionalized Ti₃C₂Tₓ MXene/SPES hybrid tight ultrafiltration membranes with improved interfacial stability for wastewater treatment

Abstract

The limited oxidation stability and affinity of Ti₃C₂Tₓ MXene with polymer restrict its application in polymeric membranes for wastewater treatment. Herein, polyphenol derivative gallic acid (GA) functionalized MXene (gMX) was incorporated into sulfonated poly (ether sulfone) (SPES) to fabricate novel gMX-SPES hybrid tight UF membranes. GA functionalization improved oxidation stability in water, dispersion of functionalized MXene (gMX) and interfacial affinity to SPES. The interfacial interactions influenced membrane morphology, pore-size distribution, average pore size, hydrophilicity, and surface charge characteristics. At an optimal gMX loading of 2 wt%, the corresponding membrane gMX2 achieved pure-water flux (J w ) of 16.4 L m⁻² h⁻¹ bar⁻¹, represents 4.3-fold enhancement over the pristine SPES membrane. In separate single-solute tests, the optimized membrane gMX2 achieved > 95% rejection of selected dyes and pharmaceuticals under synthetic feed conditions, while maintaining improved flux stability and antifouling performance during filtration of pharmaceutical-spiked hospital wastewater. During 24 h crossflow filtration of pharmaceutical-spiked hospital wastewater, the permeate flux (J p ) of gMX2 was lowered to 11 L m⁻² h⁻¹ bar⁻¹, with removal efficiencies of 77% for AMT and 54% for CIP compared to MX2. The findings further support gMX-SPES membranes as a pretreatment option for reducing pharmaceutical loads in hospital wastewater.