Oxidation of pesticides by in situ electrogenerated hydrogen peroxide: study for the degradation of 2,4-dichlorophenoxyacetic acid.
This paper reports an investigation on the performance of the H2O2 electrogeneration process on a rotating RVC cylinder cathode, and the optimization of the O2 reduction rate relative to cell potential. A study for the simultaneous oxidation of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) by the in situ electrogenerated H2O2 is also reported. Experiments were performed in 0.3 M of K2SO4, pH of 10 and 3.5. Oxygen concentration in solution was kept in 25 mg L(-1). Maximum hydrogen peroxide generation rate was reached at -1.6 V versus SCE for both, acidic and alkaline solutions. Then, 100 mg L(-1) of 2,4-D was added to the solution. First order apparent rate constants for 2,4-D degradation ranged from 0.9 to 6.3x10(-5) m s(-1), depending on the catalyst used (UV or UV+Fe(II)). TOC reduction was favored in acidic medium where a decreasing of 69% of the initial concentration was observed in the process catalyzed by UV+Fe(II). This figure was an indication that some of the intermediates derived from 2,4-D decomposition remained in solution, mainly as lighter aliphatic compounds.
Badellino
Carla
C
Faculty of Mechanical Engineering, Department of Materials Engineering, State University of Campinas, CP 6122, 13083-970 Campinas, Sao Paulo, Brazil.
Rodrigues
Christiane Arruda
CA
Bertazzoli
Rodnei
R
D015084:2,4-Dichlorophenoxyacetic Acid / Q000378:metabolism*; D001673:Biodegradation, Environmental; D004563:Electrochemistry; D006540:Herbicides / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D007700:Kinetics; D010084:Oxidation-Reduction
D006540:Herbicides; D015084:2,4-Dichlorophenoxyacetic Acid; D006861:Hydrogen Peroxide