The electrochemical phenomena and kinetics of EDTA-copper wastewater reclamation by electrodeposition and ultrasound

The use of ultrasound for the treatment of wastewater involves electrodeposition reactions with free metal ions but not with chelated-ions. The research in this paper looks at the electrochemical performance of ultrasound integrated with an electrodeposition technique for the reclamation of EDTA-copper wastewater. Since the pH and voltage strength are major working parameters of the technique, their effects on the copper removal, COD (chemical oxygen demand) degradation and current efficiency were investigated. According to experimental results, the ultrasound + electrodeposition technique can effectively remove copper (95.6%, w/w) and decompose the EDTA (84% COD removal) from the wastewater containing EDTA-copper complex compounds under certain operational control. The copper removal efficiencies follow-the order of pH 3 > pH 5 > pH 7. The removal efficiency of copper under different voltage gradients follows the order of 2.0 V cm(-1) > 1.5V cm(-1) > 1.0 V cm(-1) > 0.5 V cm(-1). A neutral pH and an appropriate voltage gradient (1.0 V cm(-1) in this case) provide the maximum current efficiency. A pseudo-first-order and zero-order mode is proper to describe the electrodeposition kinetics without ultrasonication (R(2) values are greater than 0.90) and with ultrasonication (R(2) values are greater than 0.96), respectively. Results reveal that this integration technique has potential for practical application in wastewater treatment and provides useful parameters for further research. (C) 2009 Elsevier B.V. All rights reserved.