Novel poly (ionic liquid)-based anion exchange membranes for efficient and rapid acid recovery from industrial waste

Owing to the less energy consumption, positive impact on the environment, and prospect of providing clean water resources, anion exchange membranes (AEMs) are promising materials for acid recovery from various industrial wastewater/effluent. Based on the diffusion dialysis process, AEMs selectively allow rapid proton permeation while efficiently retaining metal ions. To enhance the efficiency of the acid recovery process, precise control of macromolecular architecture and chemical composition that enables high hydrophilicity, proton conductivity through the membrane, and ion exchange capacity is required. In this direction, we report on the one-step fabrication of novel poly (ionic liquids)-based AEMs by the free radical polymerization of 1-butyl-3-vinyl imidazolium bromide, acrylic acid, styrene, and acrylonitrile under sunlight. The effect of monomer composition in an AEM matrix on the structural, physicochemical, surface, thermal, and proton conductivity is investigated. The experimentally determined acid dialysis coefficient (U_H⁺) obtained with synthesized poly (ionic liquid) based membranes PILM-1 and PILM-2 were 7.3 ± 2 and 9.2 ± 2 mh⁻¹ at room temperature (25 °C), while separation factors (SF) were 88.9 ± 3 and 50.1 ± 2, respectively. Both the U_H⁺ (>700 times) and SF (>4 times) are significantly values higher compared to the commercial AEM DF-120 (0.009 mh⁻¹ and 18.8 for U_H⁺ and SF, respectively). Thus, this study demonstrates the potential of the prepared AEMs as an alternate to deliver cost-effective, scalable, and rapid acid recovery compared to the currently existing technology.