Copper and nickel removal from plating wastewater in the electrodialysis process using a channeled stack

Abstract

Electrodialysis (ED) is an advanced separation process used to treat industrial wastewater using potential differences. In this study, flow rates within the stack were increased by creating a flow channel to increase the limiting current density (LCD). Increasing the flow rate within the stack increases the diffusion flux, which leads to an increase in LCDs. Experiments show that the applied voltage of the flow-accelerated stack was improved by 12.2% compared to the stack without a flow channel, but the LCD decreased by 3.6%. The removal efficiency of both copper and nickel between the two stacks was greater than 95.6%, with no significant difference. However, the concentration rate of ions was superior in the stack without a flow channel. This may be attributed to the fact that the applied voltage increases when the channel is attached, resulting in differences in the separation rate and the resulting concentration polarization. In terms of the current efficiency, the channel-less stack was found to be 42.5% better than the channeled stack. It would be desirable to apply voltages below the LCDs as those exceeding LCDs at the same membrane flow rate would significantly reduce the economic feasibility.