Degradation of thiamethoxam by the synergetic effect between anodic oxidation and Fenton reactions

J Meijide; J Gómez; M Pazos; M A Sanromán

doi:10.1016/j.jhazmat.2016.02.064

Degradation of thiamethoxam by the synergetic effect between anodic oxidation and Fenton reactions

J Hazard Mater. 2016 Dec 5:319:43-50. doi: 10.1016/j.jhazmat.2016.02.064. Epub 2016 Mar 2.

Authors

J Meijide¹, J Gómez¹, M Pazos¹, M A Sanromán²

Affiliations

¹ Department of Chemical Engineering, University of Vigo, Isaac Newton Building, Campus As Lagoas, Marcosende 36310 Vigo, Spain.
² Department of Chemical Engineering, University of Vigo, Isaac Newton Building, Campus As Lagoas, Marcosende 36310 Vigo, Spain. Electronic address: sanroman@uvigo.es.

PMID: 26968996
DOI: 10.1016/j.jhazmat.2016.02.064

Abstract

In this work, a comparative study using anodic oxidation, Fenton and electro-Fenton treatments was performed in order to determine the synergic effect for the removal of thiamethoxan. The results determined that electro-Fenton process showed high efficiency in comparison with Fenton or anodic oxidation. After that, this hybrid process was optimized and the influence of iron catalyst concentration and applied current intensity on the degradation and mineralization were evaluated. Degradation profiles were monitored by high performance liquid chromatography (HPLC) being satisfactorily described by pseudo-first order kinetic model. At the optimal experimental conditions (300mA and 0.2mM Fe(+2)), the complete degradation of thiamethoxam was achieved after 10min. On the other hand, mineralization of thiamethoxam was monitored by total organic carbon (TOC) decay reaching more than 92% of TOC removal after 8h. Furthermore, a plausible mineralization pathway for the thiamethoxam degradation was proposed based on the identification of by-products such as aromatic intermediates, carboxylic acids and inorganic ions released throughout electro-Fenton process.

Keywords: Anodic oxidation; Degradation; Electro-Fenton; Fenton; Thiamethoxam.