Degradation of paraquat herbicide by electrochemical advanced oxidation methods

Dhaouadi, Anissa; Adhoum, Nafaâ

doi:10.1016/j.jelechem.2009.09.027

Cited by 68 publications

(27 citation statements)

References 67 publications

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“…The comparison of the bands for the paraquat electrolyzed solutions and those for possible by-products such as paraquat monopyridone: 225, 257, and 345 nm [33] or 222, 260, 347 nm [34], and paraquat dipyridone: 224 and 320 nm [33], indicates that these compounds are the main by-products of paraquat in neutral medium. This assumption is in accordance with published data [18,21,28,32]. Parallel experiments were carried out using Pt as anode.…”

Section: Uv-vis Absorption Spectroscopysupporting

confidence: 89%

“…As the best of our knowledge, only one study was published on the anodic oxidation of paraquat aqueous solutions. Pt cathodes and carbon felt anodes were used [18]. It was proposed the formation of demethylation products of the parent compound (4, 4 0 -bipyridine and monopyridone) and hydroxylation or oxidative ring cleavage products (4-carboxy-1-methyl-pyridinium ion, 4-picolinic acid and hydroxyl-4-picolinicacid), that subsequently undertake minor degradation, leading to incomplete mineralization of the herbicide.…”

Section: Introductionmentioning

confidence: 99%

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Electrochemical oxidation of paraquat in neutral medium

Cartaxo

Borges

Pereira

et al. 2015

Electrochimica Acta

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Section: Uv-vis Absorption Spectroscopysupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Electrochemical oxidation of paraquat in neutral medium

Cartaxo

Borges

Pereira

et al. 2015

Electrochimica Acta

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“…25,26 However, a study by applying experimental design and response surface methodology that provides conclusions which result in the optimization of Fenton's reagents for PQT degradation was not reported until now. In addition, a kinetic study on the degradation of PQT by photo-Fenton process and toxicity assessment was also not published.…”

Section: -15mentioning

confidence: 99%

Degradation of the herbicide paraquat by photo-fenton process: optimization by experimental design and toxicity assessment

Trovó

Gomes

Machado

et al. 2013

J. Braz. Chem. Soc.

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Este trabalho descreve a influência e otimização dos reagentes de Fenton (concentração de Fe 2+ e H 2 O 2 ) na eficiência da mineralização do herbicida paraquat (PQT, 50 mg L -1 ) em água, após 60 min (equivalendo a 642 kJ L -1 de radiação UVA acumulada) de tratamento por processo foto-Fenton em escala de laboratório, usando planejamento composto central (CCD). Sob condições otimizadas, experimentos cinéticos foram feitos, avaliando a remoção do PQT, sua mineralização e toxicidade em escala de laboratório, usando irradiação artificial, e em planta piloto sob irradiação solar. A mesma eficiência de remoção e mineralização do PQT foram obtidas em ambos os reatores utilizados. A toxicidade das amostras, estimada em termos de mortalidade de Artemia salina, diminui simultaneamente com o decaimento da concentração de PQT, sugerindo a formação de intermediários de menor toxicidade. Dessa maneira, o processo foto-Fenton/solar pode ser considerado uma alternativa viável para o tratamento de águas residuais contendo PQT.This study describes the influence and optimization of Fenton's reagent (concentration of Fe ) in water, after 60 min (equivalent to 642 kJ L -1 of accumulated UVA radiation) treatment by photo-Fenton process in laboratory scale, using central composite design (CCD). Under optimized conditions, kinetic experiments were done, evaluating the PQT removal, its mineralization and toxicity in laboratory scale, using artificial irradiation, and in a pilot plant under solar irradiation. The same removal efficiency and mineralization of PQT were obtained in both reactors. The toxicity of the samples, estimated in terms of mortality of Artemia salina, decreases simultaneously with the decay of concentration of PQT, suggesting the formation of intermediates of lower toxicity. In this way, the solar photo-Fenton process can be considered as a viable alternative for the treatment of wastewater containing PQT.Keywords: pesticides, detoxification, pilot plant, wastewater treatment, solar light intensity IntroductionSince 2008 Brazil has overtaken the United States in pesticides consumption, becoming the largest consumer. 1 The herbicide paraquat dichloride (PQT, Figure 1) has been widely used for application in post-emergence of weeds and also as desiccant.2 Its residence time in soils can vary from 1.4 to 7.2 years depending on the concentration, soil characteristics (organic matter), temperature and rainfall.3 In river water samples, it has been observed that PQT is not easily microbiologically degraded, since, even after 56 days of incubation, more than 80% of the initial concentration remains unchanged, suggesting to PQT considerable recalcitrance. 4 In addition, PQT is polar, showing high solubility in water, as well as a low octanol-water partition coefficient (log K ow = -4.5), which provides a great mobility in some soils, arriving easily until the next water supplies.5 It has been found in the range of 2-12 mg L -1 in groundwater, 6 and, for example, at average concentration of 0.78 mg L -1 in surface waters ...

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“…Carbonaceous cathodes like graphite [26], carbon or graphite felts [12,[26][27][28][29][30], activated carbon fiber [31], carbon sponge [32], carbon-polytetrafluoroethylene (PTFE) gas (O 2 or air) diffusion [11,15,[33][34][35][36], carbon nanotubes [37,38] and BDD [14,39,40] have shown a high efficiency for H 2 O 2 electrogeneration from the twoelectron reduction of injected O 2 from reaction (2):…”

Section: Introductionmentioning

confidence: 99%

“…The most common method is electro-Fenton (EF) [11,12,15,[26][27][28][29][30]32,35,36], where • OH is produced in the bulk from the reaction between generated H 2 O 2 and low amounts of added Fe 2+ ion by Fenton's reaction (4) with optimum pH 2.8:…”

Section: Introductionmentioning

confidence: 99%