Assessing the performance of electrochemical oxidation using DSA® and BDD anodes in the presence of UVC light.

Significance of surface and ground water contamination by synthetic organic compounds has been pointed out in a very high number of papers worldwide, as well as the need of application of treatment technologies capable to assure their complete removal. Among these processes, the electrochemical advanced oxidation is an interesting option, especially when irradiated with UVC light (photo-electrochemical, P-EC) to promote homolysis of electrogenerated oxidants. In this work, the herbicide glyphosate (GLP) was used as model compound and it was electrochemically treated under UVC irradiation in the presence of NaCl and using a DSA® and BDD anodes. Total organic carbon concentration was measured throughout the electrolysis, as well as the concentration of short chain carboxylic acids and inorganic ions (NO, PO,ClO, ClO and ClO). The synergism of the P-EC was more pronounced when using a DSA® electrode, which led to complete GLP mineralization in 1 h (0.52 A h L), as also confirmed by the stoichiometric formation of NO and PO ions, with an energy consumption as low as 1.25 kW h g. Unexpectedly, the concentration evolution of oxyhalides for the P-EC process using both anodes, especially for DSA® at 10 mA cm, showed the production of ClO, whereas detection of ClO species was only found when using BDD at 100 mA cm for the electrochemical process. Finally, small amounts of carboxylic acids were detected, including dichloroacetic acid, especially when using a BDD electrode.