Degradation mechanism of fipronil and its transformation products, matrix effects and toxicity during the solar/photo-Fenton process using ferric citrate complex.

Autor: Gomes Júnior O; Universidade Federal de Uberlândia, Instituto de Química, 38400-902, Uberlândia, MG, Brazil., Batista LL; Universidade Federal de Uberlândia, Instituto de Genética e Bioquímica, 38900-402, Uberlândia, MG, Brazil., Ueira-Vieira C; Universidade Federal de Uberlândia, Instituto de Genética e Bioquímica, 38900-402, Uberlândia, MG, Brazil., Sousa RMF; Universidade Federal de Uberlândia, Instituto de Química, 38400-902, Uberlândia, MG, Brazil., Starling MCVM; Universidade Federal de Minas Gerais, Departamento de Engenharia Sanitária e Ambiental, 31270-010, Belo Horizonte, MG, Brazil., Trovó AG; Universidade Federal de Uberlândia, Instituto de Química, 38400-902, Uberlândia, MG, Brazil. Electronic address: alamtrovo@ufu.br.
Jazyk: angličtina
Zdroj: Journal of environmental management [J Environ Manage] 2020 Sep 01; Vol. 269, pp. 110756. Date of Electronic Publication: 2020 May 21.
DOI: 10.1016/j.jenvman.2020.110756
Abstrakt: This study presents the degradation of fipronil in sewage treatment plant (STP) effluent by photo-Fenton at near neutral pH (pH 6.0) using Fe 3+ /Citrate complex. 83% of fipronil degradation was reached using a molar iron/citrate ratio of 1:3 (192 μmol L -1 of Fe 3+ /576 μmol L -1 of citrate). Photo-Fenton reduced the toxicity of treated solutions as according to the survival of Drosophila melanogaster exposed to non-treated and treated samples. Control experiments performed in distilled water using 32 μmol L -1 of Fe 3+ /96 μmol L -1 of citrate achieved 98% of fipronil degradation within 100 kJ m -2 (UV-A radiation, k = 30 × 10 -3  kJ -1  m 2 and t 1/2  = 23 kJ m -2 ), thus indicating that fipronil degradation is impaired by natural organic matter and inorganic ions present in STP effluent. Degradation was faster under solar radiation, as the same efficiency (98%) was obtained after 75 kJ m -2 (k = 63 × 10 -3  kJ -1  m 2 and t 1/2  = 11 kJ m -2 ). In addition, pathways of fipronil degradation using Fe 3+ /Citrate under solar and UV-A radiation were investigated and transformation products proposed. Results revealed that the HO • attack occurred preferentially in the pyrazole ring. Eight transformation products were identified by UHPLC-Q-TOF-MS and four are unprecedented in the literature. Control experiments in distilled water demonstrated that toxicity reduction is related to fipronil degradation and that transformation products are less toxic than fipronil. Furthermore, toxicity of STP fortified with fipronil was reduced after photo-Fenton. These results demonstrate the feasibility of applying this process using Fe 3+ /Citrate complex for fipronil degradation in a real matrix.
Competing Interests: Declaration of competing interest There are no conflicts to declare.
(Copyright © 2020 Elsevier Ltd. All rights reserved.)
Databáze: MEDLINE
Externí odkaz: