Temperature resistant cross-linked brominated poly phenylene oxide-functionalized graphene oxide nanocomposite anion exchange membrane for desalination

Abstract

A new age strategic route to synthesize cross-linked nanocomposite anion exchange membranes (AEMs) from functionalized graphene oxide was reported here. Nanocomposite crosslinking networks were formed by reacting aminopropylsilane graphene oxide (AGO) with brominated poly (2,6-dimethyl-1,4-phenylene oxide) (BPPO). Amine ended functionalized graphene oxide; AGO was synthesized by condensation reaction between graphene oxide and 3-aminopropyltrimethoxysilane. A variety of nano cross-linker; AGO loading was introduced into membrane casting solution and the prepared membranes were explored based on physicochemical and electrochemical properties. The best optimized AEM; PPO/AGO-8 showed ion exchange capacity 2.2 mmol·g−1, water uptake 37.91%, swelling ratio 9.8%, conductivity 8.38 × 10−2 S·cm−1, counter ion transport number (0.97) and 108 A·m−2 limiting current density (Ilim) with maintaining good thermo-mechanical stability due to covalent interaction between polymer and nanofiller. Desalination performances were evaluated on the basis of removal ratio (RRNaCl), current efficiency (η) and energy consumption (EC) over a whole range of temperatures (25 °C to 55 °C). On being applied in ED, the PPO/AGO-8 membrane showed slightly higher RRNaCl (47.23%), η (86.0%) and lower EC (2.85 kWh·kg−1 NaCl) than commercial Fumatech FAB-PK-130 membrane (RRNaCl: 43.8%, η: 82.34% and EC: 3.21 kWh·kg−1 NaCl) under same temperature (55 °C). The superior ED performance of synthesized cross-linked nanocomposite AEM is suggested to be a promising candidate for electrodialytic desalination and temperature based separation and purification processes for industrial applications.