Aqueous Degradation of Imidacloprid and Fenothiocarb using Contact Glow Discharge Electrolysis: Degradation Behavior and Kinetics

Abstract

Degradation of the pesticides fenothiocarb and imidacloprid in water using contact glow discharge electrolysis (CGDE) achieved rates of 57.8 and 43.2% respectively. Degradation was enhanced using citric or hydrochloric acid to lower the pH to 3.0. Both acids enhanced both the degradation rate and the amount. Fenothiocarb degradation was 77.14% at pH 3 with citric acid, and 100% with HCl. Degradation of imidacloprid at pH 3 was 70.18% with citric acid and 93.02% with HCl. Acidic conditions favor either production of (OH)-O-center dot radicals or enhancement of the degradation of organic compounds by (OH)-O-center dot. Both the degradation rates and amounts for fenothiocarb and imidacloprid were reduced in the presence of methanol due to competition between pesticides and MeOH for (OH)-O-center dot. Degradation of pesticides was not completely inhibited by MeOH. Degradation of both fenothiocarb and imidacloprid using CGDE obeys a first-order rate law with high regression coefficient values (R-2>0.99).