Combined strategy of hydrodynamic cavitation and Fenton chemistry for the intensified degradation of acetamiprid

Abstract

Degradation of acetamiprid (neonicotinoid group of pesticide) has been intensified by the application of hydrodynamic cavitation (HC) in combination with Fenton and photo-Fenton process using orifice plate and circular venturi as a cavitating device. Optimization of operating parameters using circular venturi has resulted in the optimum pH of 3 and the optimum acetamiprid concentration of 10 ppm. The inlet pressure to the cavitator was optimised at 5 bar for orifice plate and 6 bar for circular venturi. The molar ratio of acetamiprid to hydrogen peroxide and Fe2+ ions to H2O2 was optimised at 1:10 and 1:30 respectively. HC based combined strategies using circular venturi have resulted in the intensification of rate of degradation of acetamiprid. The reaction rate constant of 3.35 × 10-3 min−1, 4.80 × 10-3 min−1 and 16.17 × 10-3 min−1 with synergistic coefficient of 4.16, 1.78 and 1.39 was obtained in case of HC in combination with H2O2, Fenton’s reagent and photo-Fenton process respectively. Circular venturi has witnessed higher rate of degradation of acetamiprid as compared to orifice plate in case of HC and HC based combined strategies. Degradation by-products of acetamiprid produced during HC + photo-Fenton process have been identified successfully using LC-MS/MS analysis and the degradation mechanism has been proposed.