Study on the Influence of Key Process Parameters of Electro‐Deionization on Nickel Ion Removal Efficiency from Coating Wastewater

Electrodeionization (EDI), which combines electrodialysis and ion exchange, was employed to remove nickel ions (Ni 2+ ) from electroplating wastewater. A three‐chamber electrolytic cell with ion exchange resin was used to evaluate the effects of key operational parameters such as voltage (10–25 V), temperature (20 °C–60 °C), pH (1–7), and sodium ion (Na + ) concentration (1–5 g·L −1 ). These parameters significantly influenced Ni 2+ removal efficiency. Under optimal conditions (20 V, 40 °C, pH 7, and 1 g·L −1 Na + ), the resin achieved a saturation adsorption capacity of 110.6 mg·g −1 , a 1.57‐fold increase compared to the process without an applied electric field. Saturation time was reduced to 40 min, 7.5 times faster than the original 5 h. The treated effluent met national discharge standards. Competitive adsorption between Ni 2+ and H + , and between Ni 2+ and Na + , was observed, resulting in lower removal efficiency under acidic conditions or high Na + concentrations. Current density variations were directly linked to ionic migration during electrolysis. EDI significantly enhances both the kinetics and adsorption capacity of resin‐based nickel recovery from chromium electroplating rinse wastewater, offering a promising solution for industrial‐scale heavy metal wastewater treatment with improved performance and regulatory compliance.