Degradação do herbicida Atrazina utilizando os processos foto-Fenton solar e Fenton

Abstract

The population development has affected the consumption increase in agricultural products, which leads to higher agrochemicals consumption. Thus, sprayers washing used in crops during agrochemicals applications has generated highly toxic effluents, consequently there is a great treatment need. Therefore, this research aims at investigating the effects of Fenton process parameters and the efficiency of photo-Fenton and Fenton processes on atrazine herbicide degradation. During this trial two steps were carried out. In the first step, a 2² central composite rotational design (CCRD) containing 3 central and 4 axial points for the Fenton process was proposed, with two factors: concentrations of Fe2+ (2.95, 5, 10, 15, 17.05 mg L-1) and H2O2 (29.5, 50, 100, 150 and 170.5 mg L-1), whose response factor was atrazine degradation. The obtained optimum conditions were Fe2+ = 17.05 mg L-1 and H2O2 = 128 mg L-1, and the maximum degradation was 91.00% in the validation tests. In the second step, kinetic tests were carried out using the best optimum operation conditions obtained at CCRD. The kinetics was investigated, and it reached reductions of 91.76 and 99.14%, respectively, in the Fenton and solar photo-Fenton processes, for a reaction times of 30 and 6 minutes. The behavior of pseudo-first order was observed. Although of the efficient degradation of atrazine, the results have indicated that the established values such as 2.0 μg L-1 of maximum allowed atrazine were not reached by CONAMA 357/2005 (the current Brazilian legislation). Finally, it can be concluded that the processes are promising in atrazine degradation and should be incorporated by farmers as part of the systems for the treatment of their contaminated effluents.