A novel layer-by-layer heterogeneous cation exchange membrane for heavy metal ions removal from water.

A novel layer-by-layer (LbL) cation exchange membrane was prepared for heavy metal ions removal from water via electrodialysis. LBL membranes fabricated by coating of [chitosan-co-activated carbon nanoparticles] layer on polyvinyl chloride-based heterogeneous cation exchange membrane. Betterment in adherence of layers was achieved through glutaraldehyde cross linking. FTIR, FESEM, 3D-surface images and BET analysis were used for LBL membrane characterization. Membrane surface hydrophilicity, flux, membrane potential, transport number, and their permselectivity were studied. FTIR spectra confirm LbL formation decisively. FESEM images and BET analysis demonstrated that coating of second layer on PVC membrane led to a compact structure. LbL membrane showed smoother and more hydrophilic surface compared to pristine membrane. The transport number and permselectivity increased by deposition of second layer whereas sodium flux showed up-down trend. ED experiment showed good ability in heavy metal ions removal for LBL membrane that follows (Cu> Ni> Pb) sequence. EDX analysis showed a competitive adsorption for heavy metal ions on LBL membrane as (Pb> Cu≥Ni). The effect of ultrasonic waves on regeneration of fouled membranes by heavy metals was investigated. The results showed improved performance for the regenerated membrane. Mechanical resistance also improved by utilizing of ACNs in chitosan layer.