Fabrication of Thin Film Heterogeneous Cation Exchange Membrane in Chitosan Nanocomposite Layer with Copper Oxide Nanoparticles

Hypothesis: 

The surface modification of a heterogeneous cation exchange membrane was carried out through a chitosan nanocomposite layer containing copper oxide nanoparticles in an electrodialysis process. The effect of the formed surface layer on the structure and transfer, separation and antibacterial properties of the membranes was investigated.   

Double layer membranes were produced by dip-coating method. Scanning electron microscopy (SEM), X-ray diffractometry (XRD) and Fourier transform infrared spectroscopy (FTIR-ATR), electrical resistance, ionic flux, ability to remove heavy metal ions, water content, water contact angle and antibacterial experiments were employed to examine the membranes.

The EDX and FTIR results confirmed the formation of chitosan-copper oxide nanocomposite layer on the surface of pristine membrane. The SEM images also showed the formation of a uniform layer on the modified membranes. The amount of water content for double-layer membranes showed an increasing trend compared to pristine membranes, although the contact angle results proved an increase in surface roughness for double-layer membranes. The results of ionic properties also showed that the electrical resistances of double-layer membranes decreased to 46% initially by utilizing CuO nanoparticles in the surface layer, whereas the monovalent ionic flux and bivalent flux for heavy metals were enhanced by 50% and >300%, respectively. At high ratios of CuO nanoparticles in the surface layer, the electrical resistance of membranes increased again and the flux showed a decreasing trend. Double-layer nanocomposite membranes showed a high ability to remove copper heavy metal ions and their antibacterial performance was suitable against Escherichia coli. Among the prepared membranes, the double-layer membrane containing 0.001% (by weight) copper oxide nanoparticles showed better performance compared to a pristine and other modified membranes.