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  • Study of degradation intermediates formed during electrochemical oxidation of pesticide residue 2,6-dichlorobenzamide (BAM) at boron doped diamond (BDD) and platinum-iridium anodes.

Study of degradation intermediates formed during electrochemical oxidation of pesticide residue 2,6-dichlorobenzamide (BAM) at boron doped diamond (BDD) and platinum-iridium anodes.

Chemosphere (2014-05-31)
Henrik Tækker Madsen, Erik Gydesen Søgaard, Jens Muff
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.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Boron, ≥95% (boron), amorphous powder
Sigma-Aldrich
Boron, crystalline, −60 mesh, 99% trace metals basis
Sigma-Aldrich
Boron, crystalline, 1 cm, 99.7% trace metals basis
Boron, monofilament, 5m, diameter 0.1mm
Boron, monofilament, 5m, diameter 0.2mm
Boron, monofilament, 50m, diameter 0.2mm
Boron, monofilament, 200m, diameter 0.1mm
Boron, monofilament, 50m, diameter 0.1mm
Boron, monofilament, 20m, diameter 0.2mm
Boron, monofilament, 20m, diameter 0.1mm
Boron, monofilament, 10m, diameter 0.1mm
Boron, monofilament, 10m, diameter 0.2mm
Sigma-Aldrich
Diamond, nanopowder, <10 nm particle size (TEM), ≥97% trace metals basis
Sigma-Aldrich
Diamond, nanopowder, <10 nm particle size (TEM), ≥95% trace metals basis
Sigma-Aldrich
Diamond, synthetic monocrystalline powder, ≤1 μm
Sigma-Aldrich
Iridium, foil, thickness 0.25 mm, 99.9% trace metals basis
Sigma-Aldrich
Iridium, evaporation slug, diam. × L 0.6 cm × 1.2 cm, 99.9% trace metals basis
Sigma-Aldrich
Iridium, powder, 99.9% trace metals basis
Iridium, wire reel, 0.1m, diameter 0.2mm, as drawn, 99.9%
Iridium, foil, 25x25mm, thickness 0.125mm, as rolled, 99.9%
Iridium, wire reel, 0.1m, diameter 0.15mm, as drawn, 99.9%
Iridium, wire reel, 0.1m, diameter 0.125mm, as drawn, 99.9%
Iridium, wire reel, 0.2m, diameter 0.075mm, as drawn, 99.9%
Iridium, rod, 50mm, diameter 3.0mm, as drawn, 99.9%
Iridium, wire reel, 0.2m, diameter 0.125mm, as drawn, 99.5%
Iridium, wire reel, 0.05m, diameter 0.075mm, as drawn, 99.9%
Iridium, wire reel, 0.1m, diameter 0.1mm, as drawn, 99.9%
Iridium, microfoil, disks, 10mm, thinness 0.1μm, specific density 224μg/cm2, permanent mylar 3.5μm support, 99.9%
Iridium, foil, 25x25mm, thickness 0.15mm, as rolled, 99.9%
Iridium, wire reel, 0.2m, diameter 0.125mm, as drawn, 99.9%