Preparation of Heterogeneous Cation- and Anion-Exchange Membranes by Eco-Friendly Method: Electrochemical Characterization and Desalination Performance

Abstract

This paper emphases on the preparation, characterization and application of heterogeneous cation- and anion-exchange membranes. Membranes were made by solution casting method from the blends comprises of ion-exchange resins and eco-friendly polymer binder polyvinyl alcohol (PVA). Dimensional stability of membranes in water was controlled by crosslink density of binder. Physicochemical and electrochemical characteristics of ion-exchange membranes such as ion-exchange capacity (IEC), swelling (%), water uptake (%), surface electrical resistance, and transport number have been optimized by varying the resin:binder ratio. Thermal properties of the membranes were studied using the thermogravimetric analysis and differential scanning calorimetry to evaluate the thermal degradation pattern/stability and transition temperature, i.e., Tg of ionic membranes. The morphology of membrane samples were studied using scanning electron microscope. Heterogeneous ion-exchange membranes (HIXM) prepared from the water soluble binder showed superior electrochemical properties and homogeneous morphology compared to HIXMs prepared using the organic solvent based polymer binder polyvinyl chloride (PVC) and when used for desalination in Electrodialysis stack exhibits 85.5% salt reduction.