Quaternized poly(vinyl toluene-co-α-methyl styrene)/poly(vinyl alcohol) interpenetrating anion exchange membrane for efficient acid reclamation

Abstract

With increasing urbanization and better lifestyle, more industries are being set up worldwide. Eco-friendly treatment of industrial waste is one of the major challenges to be resolved. Membrane can be a better option to treat industrial waste in sustainable manner. Herein, we report synthesis of anion exchange membrane (AEM) via. interpenetrating type crosslinked-network of N-methyl morpholine functionalized poly(vinyl toluene-co-α-methyl styrene) (PVM) and poly(vinyl alcohol) (PVA). The composition of QPVM to PVA varied from 1:1, 1:1.25, and 1:1.50 to optimize for better membrane performance in terms of ionic conductivity, proton diffusion coefficient and selectivity towards metal ions. AEM with composition of 1:1.25 PVA:QPVM (PVM-1.25) exhibits overall better physicochemical and electrochemical traits bearing ∼63% of water uptake and ⁓10.5 mS cm-1 of ionic conductivity (IC) with counter-ion transport number of 0.93. The structural and functional group analysis of prepared membranes were performed by 1H nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy. All synthesized AEMs were systematically evaluated for acid reclamation application, and results were corroborated in terms of proton diffusion coefficient (UH+), metal diffusion coefficient (UMn+)and separation factor (Sf) using variable divalent and trivalent metal ions in simulant acidic waste models. PVM-1.25 membrane showed highest proton diffusion coefficient of 39.35 × 10−3 m h−1 with separation factor of 42.57 in presence of Al3+ ions, which is ∼42% and ∼66% higher than Fe2+ (UH+= 27.71 × 10−3 m h−1 and Sf=19.87) and Zn2+ (UH+= 23.62 × 10−3 m h−1 and Sf=12.27), respectively. PVM-1.25 membrane also showed chemical, thermal and mechanical stability. Based on the results, PVM-1.25 can be considered a good candidate for reclamation of acid from industrial waste stream.