Environmental Science and Engineering Seminar
Electrochemical technologies offer an alternative solution to many environmental problems related to water management because they are versatile, efficient, cost-effective, and easily automatable. In electro-oxidation, organic pollutants can be removed by different methods:
(i) Direct electrolysis, the pollutants are oxidized after adsorption on the anode surface without the involvement of any substance other than electrons.
(ii) Oxidation via intermediates of oxygen evolution: organic compounds are oxidized near the anode surface at high potentials in the region of water discharge due to the participation of intermediates of oxygen evolution. In this case, anodes with high oxygen evolution overpotential, such as SnO2, PbO2 or boron-doped diamond (BDD), are ideal for the complete oxidation of organics to CO2 in wastewater treatment.
(iii) Indirect electrolysis is mediated by oxidizing agents generated anodically. Organic pollutants are removed through the mediation of some electroactive species generated at the anode surface, which act as intermediaries for electrons shuttling between the electrode and the organic compounds. The main oxidizing chemicals electrogenerated are active chlorines and persulfates, which are produced by the oxidation of chloride and sulphate ions commonly present in wastewater.
(iv) Electro-Fenton processes: the pollutants are removed by the hydroxyl radicals produced in the bulk of the solution using the electrogenerated Fenton's reagent. Here hydrogen peroxide is supplied in situ from the two-electron reduction of O2 on cathodes, and Fe(II) is continually regenerated from Fe(III) reduction.
(v) Coupled anodic and cathodic processes: the contaminants are treated by H2O2 generated on the cathode and oxidizing agents or hydroxyl radicals generated at the anode.
Process selection depends on the nature of the electrode material, experimental conditions, and water matrix composition. This seminar focuses on recent progress in the most promising electrochemical tools for treating aqueous matrices contaminated by organic pollutants.