Fabrication of mixed matrix heterogeneous ion exchange membrane by multiwalled carbon nanotubes: Electrochemical characterization and transport properties of mono and bivalent cations

• Selectivity was decreased by increasing MWCNTs and then increased for Na+ ions.
• Selectivity was improved by increasing MWCNTs and then decreased for Ba2 + ions.
• The monovalent ionic flux was enhanced by increase of MWCNTs' content.
• The bivalent ionic flux showed different trend by increasing MWCNTs.
• Membrane electrical resistance was decreased by increasing MWCNTs.

In this research, polyvinylchloride/multiwalled carbon nanotubes (MWCNTs) mixed matrix heterogeneous cation exchange membranes were prepared by solution casting technique. The effect of MWCNT concentration on membrane electrochemical characteristics was studied. Membrane water content was increased initially by increase of additive concentration up to 4 wt.% and then showed decreasing trend by more additive content. Increase of MWCNTs' loading ratio in casting solution also caused to decrease in ion exchange capacity. Membrane permselectivity and transport number were declined initially for monovalent ionic solution by increase of additive loading up to 4 wt.% and then increased by more additive concentration. Results revealed that membrane selectivity and transport number were improved slightly in bivalent ionic solution by increase of MWCNT concentration up to 8 wt.% and then decreased sharply by more additive concentration. The monovalent ionic flux was enhanced by increase of additive content. Also ionic flux was improved initially for bivalent ions by increase of additive concentration up to 2 wt.% and then decreased by more additive concentration from 2 to 8 wt.%. The bivalent ionic flux showed increasing trend with further increase in additive concentration. Membrane areal electrical resistance was decreased by increase of additive concentration.