Effects of alternating and direct current in electrocoagulation process on the removal of cadmium from water

• Published in: Journal of hazardous materials Vol. 192; no. 1; pp. 26 - 34
• Main Authors: Vasudevan, Subramanyan, Lakshmi, Jothinathan, Sozhan, Ganapathy
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 15.08.2011; Elsevier
• Subjects: Adsorption; Adsorption kinetics; Alternating current; Alternating/direct current; Aluminum base alloys; Anode effect; Applied sciences; Cadmium; Cadmium - isolation & purification; Cadmium removal; Cathodes; Chemical engineering; Direct current; Electrochemistry - methods; Electrocoagulation; Exact sciences and technology; Hydrogen-Ion Concentration; Isotherms; Kinetics; Microscopy, Electron, Scanning; Pollution; Reactors; Spectroscopy, Fourier Transform Infrared; Thermodynamics; Water Pollutants, Chemical - isolation & purification; X-Ray Diffraction; Adsorption kinetics; Electrocoagulation; Alternating/direct current; Cadmium removal; Isotherms; Energy consumption; Second order; Adsorption isotherm; Density; Electrodes; Adsorption; Corrosion; pH; Oxidation; Kinetics
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2011.04.081

► Very high removal efficiency of cadmium was achieved by electrocoagulation. ► Alternating current (AC) avoids oxide layer and corrosion on anode surface. ► Good current transfer between anode and cathode results more removal efficiency. ► Compact treatment facility and complete automation. ► Aluminum alloy anode prevents residual aluminum in treated water. In practice, direct current (DC) is used in an electrocoagulation processes. In this case, an impermeable oxide layer may form on the cathode as well as corrosion formation on the anode due to oxidation. This prevents the effective current transfer between the anode and cathode, so the efficiency of electrocoagulation processes declines. These disadvantages of DC have been diminished by adopting alternating current (AC) in electrocoagulation processes. The main objective of this study is to investigate the effects of AC and DC on the removal of cadmium from water using aluminum alloy as anode and cathode. The results showed that the removal efficiency of 97.5 and 96.2% with the energy consumption of 0.454 and 1.002 kWh kl −1 was achieved at a current density of 0.2 A/dm 2 and pH of 7.0 using aluminum alloy as electrodes using AC and DC, respectively. For both AC and DC, the adsorption of cadmium was preferably fitting Langmuir adsorption isotherm, the adsorption process follows second order kinetics and the temperature studies showed that adsorption was exothermic and spontaneous in nature.