Separation of Chloride and Sulfate Ions from Desulfurization Wastewater Using Monovalent Anions Selective...

The high concentration of chloride ions in desulphurization wastewater is the primary limiting factor for its reusability. Monovalent anion selective electrodialysis (S-ED) enables the selective removal of chloride ions, thereby facilitating the reuse of desulfurization wastewater. In this study, different concentrations of NaCl and Na₂SO₄ were used to simulate different softened desulfurization wastewater. The effects of current density and NaCl and Na₂SO₄ concentration on ion flux, permselectivity (PSO42-Cl-) and specific energy consumption were studied. The results show that Selemion ASA membrane exhibits excellent permselectivity for Cl^- and SO₄^2-, with a significantly lower flux observed for SO₄^2- compared to Cl^-. Current density exerts a significant influence on ion flux; as the current density increases, the flux of SO₄^2- also increases but at a lower rate than that of Cl^-, resulting in an increase in permselectivity. When the current density reaches 25 mA/cm², the permselectivity reaches a maximum of 50.4. The increase in NaCl concentration leads to a decrease in the SO₄^2- flux; however, the permselectivity is reduced due to the elevated Cl^-/SO₄^2- ratio. The SO₄^2- flux increases with the increase in Na₂SO₄ concentration, while the permselectivity increases with the decrease in Cl^-/SO₄^2- ratio.