Indirect electrochemical oxidation of 2,4-dichlorophenoxyacetic acid using electrochemically-generated persulfate

Jingju Cai (1) , Minghua Zhou (1) , Ye Liu (2) , André Savall (2) , Karine Groenen Serrano (2)

1 NKU - Nankai University
2 LGC - Laboratoire de Génie Chimique

This research investigated persulfate electrosynthesis using a boron-doped diamond anode and a chemical reaction of persulfate in its activated form with an herbicide, 2,4-Dichlorophenoxyacetic acid (2,4-D). The first part of this research is dedicated to the influence of the applied current density on the electrosynthesis of persulfate. The first part shows that for a 2 M sulfuric acid, the current efficiency reached 96% for 5 mA/cm2 and dropped to 52% for a higher current density (100 mA cm−2). This fall cannot be explained by mass transfer limitations: an increase in temperature (from 9 to 30 °C) during electrolysis leads to the decomposition of 23% of the persulfate. The second part of this research shows that a quasi-complete degradation of the target herbicide can be reached under controlled operating conditions: (i) a high ratio of initial concentrations [Persulfate]/[2,4-D], (ii) a minimum temperature of 60 °C that produces sulfate radicals by heat decomposition of persulfate, and (iii) a sufficient contact time between reactants is required under dynamic conditions.

Mots clés: Boron-doped diamond anode; Electrochemical oxidation; Sulfate radical; Persulfate; 2-4-Dichlorophenoxyacetic acid

Domaines: Autre; Ingénierie de l'environnement

Jingju Cai, Minghua Zhou, Ye Liu, André Savall, Karine Groenen Serrano. Indirect electrochemical oxidation of 2,4-dichlorophenoxyacetic acid using electrochemically-generated persulfate. Chemosphere, 2018, 204, pp.163-169. ⟨10.1016/j.chemosphere.2018.04.004⟩. ⟨hal-01949849⟩