Effect of Chloride Ions on Electro-Coagulation to Treat Industrial Wastewater Containing Cu and Ni

• Main Authors: Chien-Hung Huang, Shan-Yi Shen, Chiu-Wen Chen, Cheng-Di Dong, Mohanraj Kumar, Balasubramanian Dakshinamoorthy, Jih-Hsing Chang
• Format: Article
• Language: English
• Published: MDPI AG 2020-09-01
• Series: Sustainability
• Subjects: copper; current efficiency; electro-coagulation; nickel; wastewater
• Online Access: https://www.mdpi.com/2071-1050/12/18/7693

A series of experiments with different NaCl concentrations added to the PCB (printed circuit board) wastewater were prepared to investigate the chloride effect on the formation of aluminum floc and removal efficiency of Cu and Ni. The effects of pH, current density, and different concentration of NaCl were studied and the results are discussed. Results imply that chloride ions are favored to avoid the passivation of the aluminum anode in the EC (electro-coagulation) system. Chloride ions used as the electrolyte can facilitate the release of Al³⁺, which results in the current efficiency of over 100% in the EC system. For the PCB factory’s wastewater, the EC system could remove Cu²⁺ and Ni²⁺ effectively (both Cu and Ni concentration of treated wastewater was less than 1.0 mg/L within three minutes). PCB wastewater’s pH value could maintain stably about 9.0 in the EC system when the initial pH value was around 2.5. The estimated electricity consumption for treating PCB wastewater by the EC process was about 0.894 kWh for each meter of cubic wastewater.