Sulfonated poly(ether ether ketone)/imidized graphene oxide composite cation exchange membrane with improved conductivity and stability for electrodialytic water desalination

Abstract

Sulfonated poly(ether ether ketone) (SPK)/imidized graphene oxide (IGO) composite cation exchange membrane (CEM) with varied composition was prepared and assessed as a promising candidate for water desalination by electrodialysis (ED). Incorporation of multi-functionalized (SO3H and COOH) IGO in SPK matrix leads a high performance CEM with improved electrochemical and physicochemical properties (conductivity, permselectivity, water content and ion-exchange capacity), stabilities (thermal, mechanical, and chemical) essential for diversified electro-membrane processes. Due to the presence of multi-functional oxygenated groups, strong hydrogen bonding between IGO and SPK led suitable hydrophobic–hydrophilic architecture and formation of ionic clusters responsible for ion conducting channels. Well optimized SPK/IGO-8 composite CEM exhibited good water uptake (32.56%), ion-exchange capacity (2.16 meq·g−1), high permselectivity (0.87), and conductivity (5.40 × 10−2 S cm−1) due to high molality of sulphonic acid groups. Relatively high limiting current density (Ilim) value for SPK/IGO-8 composite CEM provide a broad window for applying high current density across the electrodialyser to achieve fast water desalination without any unwanted water splitting. Further, low frictional coefficient between counter-ion and membrane matrix plus good electrodialysis performance of SPK/IGO-8 composite CEM revealed its potential candidate for water desalination.