Separation of metals from electroplating wastewater using electrodialysis

ABSTRACT

In this study, the separation of metals from electroplating wastewater using an electrodialysis system was investigated. The separation efficiency of the metal ions increased as the applied voltage was increased from 6 to 18 V. However, at 18 V white sediments formed due to the high current density. The limiting current density (LCD) in the tested wastewater was calculated to be 22.5 mA/cm² and the optimum applied voltage was estimated to be 12 V. The electrical conductivity of the diluate was reduced by 96.8%, and the conductivity of the concentrate increased. The separation efficiency of copper and nickel nearly identical, and after 25 min of operation, the removal efficiency of both metals was ˃99%. The final concentrations of Cu²⁺ and Ni²⁺ in the circulating concentrate were 1,000 and 1,200 mg/L with recovery rates of 90.7% and 90.2%, respectively. Thus, it was suggested that electrodialysis could effectively treat electroplating wastewater and recover ˃90% of the metals.

KEYWORDS:

• Electrodialysis
• metal
• ion exchange membrane
• electroplating wastewater
• limiting current density

Additional information

Funding

This study was supported by the Korea Ministry of Environment (MOE) as part of the “Technologies for the Risk Assessment & Management Program (2017000140006)” and the Human Resources Program in Energy Technology of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted financial resource from the Ministry of Trade, Industry and Energy, Republic of Korea (No. 20174010201540).