title: Study of degradation intermediates formed during electrochemical oxidation of pesticide residue 2,6-dichlorobenzamide (BAM) at boron doped diamond (BDD) and platinum-iridium anodes.
abstract: Electrochemical oxidation is a promising technique for degradation of otherwise recalcitrant organic micropollutants in waters. In this study, the applicability of electrochemical oxidation was investigated concerning the degradation of the groundwater pollutant 2,6-dichlorobenzamide (BAM) through the electrochemical oxygen transfer process with two anode materials: Ti/Pt90-Ir10 and boron doped diamond (Si/BDD). Besides the efficiency of the degradation of the main pollutant, it is also of outmost importance to control the formation and fate of stable degradation intermediates. These were investigated quantitatively with HPLC-MS and TOC measurements and qualitatively with a combined HPLC-UV and HPLC-MS protocol. 2,6-Dichlorobenzamide was found to be degraded most efficiently by the BDD cell, which also resulted in significantly lower amounts of intermediates formed during the process. The anodic degradation pathway was found to occur via substitution of hydroxyl groups until ring cleavage leading to carboxylic acids. For the BDD cell, there was a parallel cathodic degradation pathway that occurred via dechlorination. The combination of TOC with the combined HPLC-UV/MS was found to be a powerful method for determining the amount and nature of degradation intermediates.
authors.affiliation: Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Niels Bohrs Vej 8, 6700 Esbjerg, Denmark. Electronic address: htm@bio.aau.dk.
authors.forename: Henrik Tækker
authors.initials: HT
authors.lastname: Madsen
authors.affiliation: Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Niels Bohrs Vej 8, 6700 Esbjerg, Denmark.
authors.forename: Erik Gydesen
authors.initials: EG
authors.lastname: Søgaard
authors.affiliation: Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Niels Bohrs Vej 8, 6700 Esbjerg, Denmark. Electronic address: jm@bio.aau.dk.
authors.forename: Jens
authors.initials: J
authors.lastname: Muff
mesh_terms: D001549:Benzamides / Q000737:chemistry*; D001895:Boron / Q000737:chemistry; D002264:Carboxylic Acids / Q000737:chemistry; D018130:Diamond / Q000737:chemistry; D055664:Electrochemical Techniques; D004566:Electrodes; D007495:Iridium / Q000737:chemistry; D010084:Oxidation-Reduction; D010573:Pesticide Residues / Q000032:analysis / Q000737:chemistry*; D010984:Platinum / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D001549:Benzamides; D002264:Carboxylic Acids; D010573:Pesticide Residues; D014874:Water Pollutants, Chemical; D007495:Iridium; D010984:Platinum; D018130:Diamond; C057454:2,6-dichlorobenzamide; D001895:Boron
keywords: 2,6-Dichlorobenzamide; Degradation intermediates; Electrochemical oxidation; Groundwater; Pesticide pollution