Surface Modification of Cation Exchange Membranes Using Amorphous Zirconium Phosphate to Remove Chlorine Ions From Desulfurization Wastewater

ABSTRACT In order to eradicate chloride ions and impede cathodic scaling in the single‐membrane, dual‐cell electrolytic process for desulfurization wastewater treatment, an in situ chemical modification technique was employed to directly introduce amorphous zirconium phosphate to the surface and within the pores of the IONSEP‐CIM cation exchange membrane. The surface morphology, crystal structure, and elemental valence states of the prepared membrane were characterized using scanning electron microscopy (SEM), x‐ray diffraction (XRD), x‐ray photoelectron spectroscopy (XPS), and attenuated total reflection Fourier transform infrared (ATR‐FTIR) spectroscopy. It was established that the zirconium phosphate particles were present on the surface of the modified membrane, and that they had partially filled the surface pores of the membrane, thereby forming a bilayer structure along the pore surfaces. Furthermore, the recently incorporated phosphate groups on the modified membrane exhibited potent coordination with divalent ions, efficaciously adsorbing calcium and magnesium ions and diminishing their transport through the membrane. The membrane's Na/Mg selectivity coefficient exhibited a marked increase from 56% to 171%, while the Na/Ca selectivity coefficient demonstrated a substantial rise from 37% to 105%.