Fenton and Fenton-like oxidation of pesticide acetamiprid in water samples: Kinetic study of the degradation and optimization using response surface methodology

摘要

The aims of this study were (a) to evaluate the degradation of acetamiprid with the use of Fenton reaction, (b) to investigate the effect of different concentrations of H_2O_2 and Fe~(2*), initial pH and various iron salts, on the degradation of acetamiprid and (c) to apply response surface methodology for the evaluation of degradation kinetics. The kinetic study revealed a two-stage process, described by pseudo- first and second order kinetics. Different H_2O_2:Fe~(2*) molar ratios were examined for their effect on acetamiprid degradation kinetics. The ratio of 3mgL~(-1) Fe~(2*): 40mgL~(-1) H_2O_2 was found to completely remove acetamiprid at less than lOmin. Degradation rate was faster at lower pH, with the optimal value at pH 2.9, while Mohr salt appeared to degrade acetamiprid faster. A central composite design was selected in order to observe the effects of Fe~(2*) and H_2O_2 initial concentration on acetamiprid degradation kinetics. A quadratic model fitted the experimental data, with satisfactory regression and fit. The most significant effect on the degradation of acetamiprid, was induced by ferrous iron concentration followed by H_2O_2. Optimization, aiming to minimize the applied ferrous concentration and the process time, proposed a ratio of 7.76 mgL-1 Fe(Ⅱ): 19.78 mg L~(-1) H_2O_2. DOC is reduced much more slowly and requires more than 6 h of processing for 50% degradation. The use to zero valent iron, demonstrated fast kinetic rates with acetamiprid degradation occurring in 10 min and effective DOC removal.