Binary hetero-structured PVDF/TiO2@MXene composite membranes for the removal of antibiotics from wastewater

Abstract

The presence of pharmaceuticals in hospital wastewaters has generated significant interest among researchers. Current membrane technologies face limitations in effectively removing these emerging contaminants, which has led to continuous advancements in the field. Two-dimensional (2D) nanomaterial-based membranes have proved their ability in providing high water permeability without compromising separation performance. In this study, a binary hetero-structured PVDF/TiO2@MXene composite 2D membrane was prepared and utilized for the rejection of antibiotics, namely tetracycline and meropenem. Vacuum-assisted filtration was employed to fabricate the photocatalytic and highly selective multi-layer TiO2@MXene stacked sheets on hydrophilic PVDF microfilters. The attachment of TiO2 nanoparticles in the MXene structure has significantly improved the wettability and permeation of the PVDF/TiO2@MXene membrane, with a water contact angle of 19.5° and a permeation capacity of 293 L.m−2.h−1.bar−1. In terms of antibiotic rejection, the developed membrane demonstrated a rejection of 87.8% and 60.7% for tetracycline and meropenem solutions, respectively, through interlayer sieving, adsorption, and photocatalysis. The membrane also performed ideally in neutral pH conditions often present in hospital wastewaters, when compared to acidic and alkaline conditions, aiding in the membrane's adsorptive interactions under UV irradiation. When studied in antibiotic mixtures and spiked real hospital wastewater feed solutions, the membrane exhibited a rejection rate of 77.4% and 70.1% for tetracycline, respectively. This research represents a promising approach to addressing the challenges posed by pharmaceuticals in hospital wastewaters through the synergistic utilization of MXene and anatase TiO2.