Fabrication of novel mixed matrix electrodialysis heterogeneous ion-exchange membranes modified by ilmenite (FeTiO3): electrochemical and ionic transport characteristics

Abstract

Novel mixed matrix polyvinylchloride-based electrodialysis heterogeneous cation-exchange membranes were prepared by casting technique. Ilmenite (FeTiO3) was employed as additive in membrane fabrication. The effect of additive concentration on electrochemical properties of membranes was studied. Water content was decreased slightly by increase of FeTiO3 concentration. Ion-exchange capacity was improved initially by increase in additive content to 16 wt.% and then showed decreasing trend by more additive loading. Membrane potential, transport number and selectivity were enhanced initially in NaCl solution by increase of FeTiO3 content up to 16 wt.% and then decreased by more additive loading. Increment of FeTiO3 concentration led to decrease of selectivity and transport number in BaCl2 solution. Permeability and flux were declined slightly by increase in additive content up to 8 wt.% and then began to increase sharply by more additive content from 8 to 16 wt.%. Permeability and flux were decreased again by more additive concentration from 16 to 32 wt.%. Electrodialysis experiment results in laboratory scale showed higher dialytic rate for modified membrane compared to pristine one. Membrane areal electrical resistance was declined by increase of additive concentration. Membranes exhibited higher selectivity and flux for monovalent ions compared to bivalent ones.