Engineering robust RGO/PVA composite membrane for acid recovery via electron beam irradiation

Abstract

As a cost-effective and eco-friendly approach to acid recovery, diffusion dialysis (DD) has attracted much attention but still suffers from dissatisfactory selectivity and low-efficiency, especially for low-concentration acidic wastewater. Herein, a robust graphene-based composite membrane was fabricated for high-selective acid recovery via DD process from low-concentration acidic solution by starting from graphene oxide (GO) and polyvinyl alcohol (PVA) mixed dispersion, which was treated by electron beam (E-beam) irradiation and vacuum-filtration in sequence. It was proved that the E-beam irradiation not only initiated the GO reduction, but also caused covalent PVA decoration on sheets, which endowed the obtained composite membrane with tolerance to intense ultrasonication and resistance to swelling in water. Tunable ability to block metal ion permeation and higher H+ permeation than coexisting metal ions also were substantiated, which contributed to around 5.1 × 10−3 m h−1 of H+ dialysis coefficients (UH+) from low-concentration mixed HCl solution (pH = 1, 0.2 mol L−1 metal chloride), rivaling that of commercial DD membrane (DF-120B) from high-concentration acid solution (≥1 mol L−1). More importantly, separation factor from the HCl/FeCl3 mixed solution reached up to 387.2, an order of magnitude higher than that of DF-120B membrane (24.3) and also superior to most of the reported DD membranes.