Electrochemical Treatment of Hazardous Organic Pollutants – A Status Review

Abstract

The rapid industrial development, while giving a significant boost to the quality of human life, has also taken a heavy toll on our environment.  One of the manifest effects is the proliferation of hazardous organic pollutants in the environment. These pollutants have many environmental and health implications like persistence and biomagnification, mutagenic and carcinogenic nature, endocrine disruption, and ecotoxicity to name a few.

Being mostly non-biodegradable or biorecalcitrant, they cannot be effectively treated with biological wastewater treatment methods. Physical separation methods only shift the pollutants from one stream to the other pending a final disposal. Advanced treatment techniques are, therefore, needed to deal with such pollutants. Against this backdrop, the electrochemical treatment methods are significant and relevant.

Electrocoagulation utilizes a sacrificial anode, often iron or aluminium, for the in-situ generation of Fe(III) or Al(III) ions as the coagulationg agent. This method has been found to be partially successful in the remediation of wastewater containing hazardous organic pollutants. But the most important of the electrochemical treatment methods is fast emerging technique of Electrochemical Advanced Oxidation, also known as Electrochemical Incineration. This aims at mineralization of the target pollutant by generating highly reactive hydroxyl radicals at the anode through dissociation of the water molecule. Certain pollutants also undergo direct oxidation at the anode through electrochemical charge transfer. The anode material, the inter-electrode potential, current density, and the supporting electrolyte have all been found to affect the process. Hydrogen is generated at the cathode which further adds to the attractiveness of the process.

Keywords: Hazardous organic pollutants, electrochemical incineration, electrocoagulation, anode material