In this study, silicon dioxide nanoparticles (SiO2 NPs) were functionalized by polyacrylic acid (PAA) then used as the modifier agent in polyvinyl chloride (PVC)-based heterogeneous cation exchange membranes (CEMs). FTIR technique and SEM images were employed to characterize the synthesized SiO2/PAA. All the experiments were carried out at ambient condition. According to the experiments, CEMs modified by SiO2/PAA have more hydrophilic and smoother surface. Membrane water content reduced from 32.2% for the base membrane to 20.1% for modified membrane containing 4.0%wt SiO2/PAA. Modified CEMs showed an improved potential, transport number, selectivity, and electrical conductivity. The selectivity of modified membrane (containing 0.5%wt SiO2/PAA) is 87.3%, and its electrical conductivity is about 37%less than the base membrane. The mechanical stability of prepared membranes was also improved about 25.4%. Moreover, sodium flux increased sharply (21%) loading 0.5%wt NPs in the structure and then reduced by more SiO2/PAA concentration. In addition, membrane ionic flux decreased obviously for bivalent ions by using SiO2/PAA nanoparticles. The prepared membranes showed higher permeability/flux for monovalent ions compared to bivalent type.
