Potential of Textile Wastewater Decolorization Using Cation Exchange Membrane Electrolysis Coupled with Magnesium Salt Precipitation (CEM-MSP)

To overcome the low efficiency, high cost and less environmentally friendly limitations in existing textile wastewater disposal technology, an innovative approach of cation exchange membrane electrolysis coupled with magnesium salt precipitation (CEM-MSP) was implemented. This method simultaneously achieved the high-efficiency adsorption decolorization of dyes and the recovery of lye. The results indicated that cation exchange membrane electrolysis with MgSO4added to the anode chamber (CEM-EA) exhibited excellent decolorization performance on DB86 dye and achieved low residual Mg2+concentration. Furthermore, the adsorption mechanism of Mg(OH)2on DB86 was systematically investigated. The adsorption process fitted with the first-order kinetic, where the adsorption of DB86 by Mg(OH)2was dominated by electrostatic attraction. Detailed comparison of the four systems demonstrated that CEM-EA was superior to the single magnesium addition method (85.24%) or the stand-alone membrane electrolysis method (10.36%), with 99% decolorization efficiency. In comparison to the cation exchange membrane electrolysis with MgSO4added to the cathode chamber (CEM-EC), the CEM-EA could diminish the Mg2+concentration in the effluent to facilitate the lye recovery while guaranteeing the decolorization efficiency. In addition, the DB86 adsorption behavior during the formation of Mg(OH)2in the cathode chamber was investigated. The Mg(OH)2particles were relatively dense copper-blue agglomerates with a thin lamellar layer on the surface. Notably, only slight mass contamination was observed on the cation exchange membrane (CEM) surface after multiple cycles. Minor CEM contamination illustrated the stable treatment efficiency of the CEM-EA after several cycles. This study constructed a novel approach integrating membrane electrolysis with magnesium salt precipitation, delivering valuable technical solutions for textile wastewater disposal.