Tratamento de águas contaminadas por atrazina via sistema fotofenton utilizando lâmpada led como fonte de energia: eficiência na remoção, mecanismo e degradação

Abstract

Atrazine is a broad spectrum non-selective systemic herbicide used against a wide variety of agricultural pests and weeds. ATZ is extremely toxic to living things and to the environment due to its persistence and mobility. In addition, in water treatment plants, the control, removal and disposal of this agrochemical is deficient (~ 25%) in conventional treatment processes. For this reason, this study focused on photo-Fenton LED degradation of atrazine in aqueous solution. The analytical route was evaluated to determine and quantify ATZ by HPLC, investigating the effects of hydrogen peroxide, ferric ion concentrations and radiation levels on atrazine degradation processes. The experimental work was carried out in a well-stirred laboratory reactor irradiated with LED lamp and the analytical route was developed to determine the ATZ and the validation of the method implied the determination of the precision in 93-103% with LD and LQ in 0, 39 and 1.3 mg L-1, respectively. The factorial design of the experiments of 23 was used to optimize the degradation system via photo-Fenton LED system with maximum average error for all estimates less than 10%. The results of atrazine degradation (30mg L-1) and 30mg L-1 (30mg L-1) in the aqueous solution of 30mg L-1 allowed to degrade approximately 98% of atrazine in only 240 minutes of reaction and the observed mineralization was 60% of organic carbon (TOC). Several byproducts have been identified by UPLC / MS (such as HA, DEA, DIA, HDEA, HDIA and HDEDIA) and the mechanism of degradation following dechlorination and hydroxylation that they produce is HDEDIA or ammelide. The results obtained in the photo-Fenton system with LED lamp as a source of radiation is very efficient for the removal of atrazine in aqueous solutions and offers several advantages over the traditional system, because it has low energy consumption and is more ecologically correct.