Surface modification of heterogeneous cation exchange membranes by simultaneous using polymerization of (acrylic acid-co-methyl methacrylate): Membrane characterization in desalination process

• PAA-co-PMMA/PVC composite cation exchange membranes were prepared.
• PAA-co-PMMA was used as surface modifier by graft polymerization technique.
• Selectivity was improved by surface modification/SDBS ratio in used emulsion.
• Ionic flux was enhanced sharply by PAA-co-PMMA graft polymerization.
• E-resistance was decreased by graft polymerization/SDBS ratio increase.

In the current research poly(vinyl chloride) based composite heterogeneous cation exchange membranes were prepared by solution casting technique. Poly(acrylic acid)-co-poly(methyl methacrylate) was used as membrane surface modifier by emulsion/graft polymerization technique to improve the membrane electrochemical properties. Also the effect of used emulsifier content ratio in modifier emulsion on properties of membranes was studied. The FT-IR spectrum analysis decisively proved the graft polymerization of poly(acrylic acid)-co-poly(methyl methacrylate). SOM images showed uniform particle distribution and relatively uniform surfaces for the membranes. Results revealed that surface modification of membrane led to increase in membrane potential, transport number, selectivity, surface charge density, ion exchange capacity and ionic permeability in modified membranes. Also, results showed that increase of emulsifier (SDBS) ratio in used emulsion led to increase in membrane transport number, selectivity and ionic flux for the modified composite membranes. Conversely, opposite trends were found for membrane electrical resistance by AA-co-MMA polymerization.