Double layer Cation Exchange Membranes (DLCEMs) have been prepared by surface polymerization of dopamine-co-POSS nanoparticles on a PVC based heterogeneous cation exchange membrane. FTIR and FESEM images proved relatively uniform forming of intended DLCEMs. The FESEM images illustrated almost integrity dispensation of nanoparticles through the surface layer. Results represented that developing nanocomposite layer resulted in surface hydrophilicity enhancement. The obtained data for Cu2+ and Cr2+ removal percentage for the prepared membranes represents higher capacity for DLCEMs to remove heavy metals compared to pristine cationic membrane. Also membranes showed higher Cr2+ removal capacity rather than Cu2+. The membrane surface modification by introducing PDA nanocomposite also caused to improving sodium permeability and flux. Furthermore, transport number and permselectivity of the prepared CEMs generally follow an increasing procedure nearly. It should be noticed that incorporation of POSS nanoparticles into the surface layer resulted in electrical resistance reduction obviously.
