Silane functionalized graphene oxide-bound polyelectrolyte layers for producing monovalent cation permselective membranes

Abstract

This study reports a novel layer-by-layer (LbL) strategy for producing a monovalent cation perm-selective membrane with an improved antifouling property. LbL architectures were fabricated by using the polyvinyl chloride (PVC) based heterogeneous cation exchange membrane as the substrate and chitosan (CS) and polyacrylic acid (PAA) as the polycation and polyanion, respectively. The coating layers on the substrate consist of 1.5 bilayers with CS as the initiating and terminating layer and PAA blended with silane functionalized graphene oxide (S-f-GO) as the middle layer. Molecular electrostatic potential (MEP) of the utilized materials proved the availability of appropriate reactive sites in their structures. FTIR spectra, EDX analysis, zeta-potential measurement, and FESEM images verified successful LbL assembly of CS and PAA blended with S-f-GO. The presence of S-f-GO in the anionic layer of the LbL architectures caused more compactness of the terminating cationic layer and increased the porosity of the anionic layer. LbL membranes containing S-f-GO possessed lower surface roughness and more hydrophilic surface and provided higher antifouling property, monovalent selectivity, and electrical conductivity than LbL architecture without additive. Results showed that utilizing 2 wt% S-f-GO in the anionic layer led to increasing permselectivity (PMg2+Na+)from 1.03 to 6. Also, the incorporation of S-f-GO was found to enhance the regeneration ability of the LbL membranes. This novel strategy for producing the MCPM can open up a new insight into designing advanced monovalent selective ion exchange membranes.