Electrodialysis of a sodium sulphate solution with experimental bentonite-modified bipolar membranes

Abstract

The aim of this work is to study the characteristics of the electrodialysis of a sodium sulphate solution with experimental bipolar membranes based on the MA-41 anion exchange membrane and a liquid sulphonated cation-exchanger modified with bentonite clays. The conversion of sodium sulphate was conducted by electrodialysis with bipolar membranes obtained by applying a liquid sulphonated cation-exchanger containing particles of bentonite clay to the MA-41 anion-exchange membrane. To increase the performance of membranes in terms of hydrogen and hydroxyl ions, we carried out organomodifications of bentonite with alkyldimethylbenzylammonium chloride and stearic acid at various concentrations. The bipolar membrane with the addition of bentonite modified with alkyldimethylbenzylammonium chloride (2 wt%) showed a higher performance in terms of H+-ions. The bipolar membrane with bentonite modified with stearic acid (3 wt%) added to its cation-exchange layer is the most effective in terms of obtaining a flux of OH--ions. It was shown that a combination of alkyldimethylbenzylammonium chloride (2 wt%) and stearic acid (3 wt%) used to modify bentonite can increase the performance of the bipolar membrane during the conversion of sodium sulphate, both in terms of the acid and alkali.

Keywords

• electrodialysis
• bipolar membrane
• modification
• bentonite
• organobentonite
• sodium sulphate
• acid
• alkali