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Title: Paired electro-oxidation of insecticide imidacloprid and electrodenitrification in simulated and real water matrices
Author: Oriol, Roger
Bernicola, M.P.
Brillas, Enric
Cabot Julià, Pere-Lluís
Sirés Sadornil, Ignacio
Keywords: Oxidació electroquímica
Hidrologia d'aigües subterrànies
Electrolytic oxidation
Groundwater hydrology
Issue Date: 9-May-2019
Publisher: Elsevier Ltd
Abstract: Groundwater is one of the main freshwater resources on the Earth, but its contamination by NO3− and pesticides jeopardizes its suitability for consumption. In this work, the simultaneous electro-oxidation of insecticide imidacloprid (IMC) and electroreduction of NO3− in softened groundwater containing a large amount of Cl− has been addressed. The assays were carried out in a stirred undivided tank reactor containing either a boron-doped diamond (BDD) or IrO2 anode, and Fe cathode, which showed greater electrocatalytic activity than stainless steel to reduce NO3−. Comparative assays in simulated water mimicking the anionic composition of groundwater were made to assess the influence of natural organic matter (NOM) on the decontamination process. The BDD/Fe cell had much greater performance than the IrO2/Fe one, although the former produced larger amounts of ClO3− and ClO4−. In all cases, the NO3−, Cl− and IMC decays agreed with a (pseudo)-first-order kinetics. In the BDD/Fe cell, total NO3− removal was reached at j ≥ 10 mA cm−2 in softened groundwater, at similar rate in the presence and absence of IMC, but it was decelerated using the simulated matrix. The N-products formed upon NO3− electroreduction contributed to IMC degradation, but its decay was inhibited by NOM because of the partial consumption of oxidants like hydroxyl radical and active chlorine. Operating at 5 mA cm−2 for 240 min, total removal of the insecticide and 61.5% total organic carbon (TOC) decay were achieved, also attaining a low NO3− content that was suitable for humans. Eight heteroaromatic products were identified, allowing the proposal of a reaction sequence for IMC degradation in groundwater.
Note: Versió postprint del document publicat a:
It is part of: Electrochimica Acta, 2019, vol. 317, p. 753-765
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ISSN: 0013-4686
Appears in Collections:Articles publicats en revistes (Ciència dels Materials i Química Física)

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