Reductive/oxidative treatment with superior performance relative to oxidative treatment during the degradation of 4-chlorophenol

Raja, P.; Bozzi, Anna; Jardim, Wilson F.; Mascolo, G.; Renganathan, R.; Kiwi, J.

doi:10.1016/j.apcatb.2005.02.014

Cited by 36 publications

(17 citation statements)

References 17 publications

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“…These differences can be attributed in part to the aforementioned chlorinated aromatic species (4,6-dichloro-1,2-benzenediol, 4,6-dichloro-1,3-benzenediol and 4-CC) which were detected in trace amounts (<1 lg/L). Although the occurrence of polymerization reactions has been commonly reported in Fenton oxidation of phenolic compounds [33,39,41,42], condensation byproducts have not been detected in this study. The chlorine balances matched always around 95%.…”

Section: Oxidation Byproductscontrasting

confidence: 40%

Triclosan breakdown by Fenton-like oxidation

Muñoz

Pedro

Casas

et al. 2012

Chemical Engineering Journal

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Fenton-like oxidation has proved to be highly efficient for the removal of triclosan, a highly toxic emerging water pollutant. From 10mg/L starting aqueous solutions complete conversion of triclosan was achieved in less than 1h at 25°C and around 20min at 50°C with 1mg/L Fe3+ and H2O2 at the theoretical stoichiometric amount (25mg/L). From the evolution of byproducts a reaction pathway has been proposed according to which oxidation of triclosan gives rise to several aromatic intermediates (mainly, p-hydroquinone of triclosan and 2,4-dichlorophenol) which evolve to short-chain organic acids. These compounds are mineralized except oxalic acid. A dramatic decrease of ecotoxicity was achieved in a relatively short time (more than 95% in 15min at 35°C). The evolution of ecotoxicity is intimately related to the disappearance of triclosan, much more toxic than the aromatic oxidation intermediates. This disappearance was successfully described by a simple pseudo-first order rate equation with an apparent activation energy value close to 27kJ/mol. The apparent rate constant at 25°C was several orders of magnitude higher than the reported in the literature for other chlorophenolic compounds indicating a higher susceptibility of triclosan to OH radical attackThis research has been supported by the Spanish MICINN through the project CTQ2008-03988 and by the CM through the project S-2009/AMB-158

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Section: Oxidation Byproductscontrasting

confidence: 40%

Triclosan breakdown by Fenton-like oxidation

Muñoz

Pedro

Casas

et al. 2012

Chemical Engineering Journal

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“…Especially in the 1990s, researches on zero-valent iron were carried out broadly. Degradation performance, kinetics, reaction conditions, field tests were developed [10][11][12][13][14][15][16]. Due to their high specific surface area and high surface reactivity, nanoscale iron particles offer much more advantages for treatment of chlorinated phenols compared to conventional iron particles [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Comparison of reductive dechlorination of p-chlorophenol using Fe0 and nanosized Fe0

Cheng

Wang

Zhang

2007

Journal of Hazardous Materials

170

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“…These processes can be used to initiate remediation of complex anthropogenic chemicals, such as nitro and chlorinated aromatic compounds. [7][8][9][10][11] Dyes are another category of complex chemicals that are labile to reduction, as already shown for several dyes. [12][13][14][15][16][17][18] Several metals (such as Zn, Sn, Pt) can be used as reduction agents, but iron has received the foremost emphasis due to its high efficiency in addition to its low cost and toxicity.…”

Section: Introductionmentioning

confidence: 99%

Degradation of food dyes by zero-valent metals exposed to ultrasonic irradiation in water medium: optimization and electrospray ionization mass spectrometry monitoring

Pavanelli¹,

Bispo²,

Nascentes³

et al. 2011

J. Braz. Chem. Soc.

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A degradação redutiva de quatro corantes típicos (Azul Brilhante, Amaranto, Amarelo Crepúsculo e Vermelho 40), largamente empregados pela indústria alimentícia, por metais de valência zero (Fe e Sn), sob irradiação ultrassônica (US) em meio aquoso ácido (pH 3,0), foi estudada. As reações foram monitoradas por ESI(-)-MS (espectrometria de massas com ionização electrospray no modo negativo), além de espectrofotometria UV-Vis e carbono orgânico total (TOC). A influência de parâmetros preponderantes (tempo de exposição à radiação ultrassônica e massa do metal) nas taxas de degradação foi seguramente estabelecida por meio da construção de planejamentos fatoriais e superfícies de resposta. Deste modo, observou-se que, sob as condições experimentais otimizadas, ferro metálico (Fe) degradou eficientemente todos os corantes (com taxas de degradação superiores a 90% após 30 min de reação), enquanto que estanho metálico (Sn) apresentou um desempenho notavelmente inferior. As baixas taxas de mineralização obtidas foram consequência, provavelmente, do caráter essencialmente redutivo de tais processos. Baseado nos resultados do monitoramento por ESI(-)MS, uma rota de degradação plausível para o corante Azul Brilhante em meio aquoso, pelo sistema Fe/US, foi proposta e envolve, como etapas iniciais, a hidrogenação da ligação dupla exocíclica carbono-carbono, seguida pela inserção de hidreto no grupamento imino da molécula.The reductive degradation of four prototype dyes largely employed by the food industry (Brilliant Blue, Amaranth, Sunset Yellow and Red 40), by zero-valent metals (Fe and Sn) under ultrasonic irradiation in acidic aqueous solution (pH 3.0), was studied. The reactions were monitored by direct infusion ESI(-)-MS (electrospray ionization mass spectrometry in the negative ion mode) as well as by UV-Vis and total organic carbon (TOC). The influence of major parameters (time of exposure to ultrasonic irradiation and mass of metal) on the degradation rates was firmly established by means of factorial design and surface response approaches. Hence, it was noticed that, under the optimized experimental conditions, metallic iron (Fe) was able to efficiently degrade all the dyes (with rates higher than 90% after 30 min reaction time), whereas metallic tin (Sn) exhibited a noticeably lower performance. Low mineralization rates were achieved probably due to the essentially reductive character of such process. Based on the results from the ESI(-)-MS monitoring, a plausible degradation route for the Brilliant Blue dye in aqueous medium by the Fe/US system was proposed. Hence, this route involves, as initial pathways, the hydrogenation of the exocyclic carbon-carbon double bond of the dye followed by the insertion of hydride at its imino moiety. Keywords: electrospray ionization mass spectrometry, monitoring, food dyes, zero-valent metals IntroductionColor is by far the most important sensorial property of foods. In this way, dyes have been widely used to accentuate their original colors, or to provide different ones.While bei...

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Reductive/oxidative treatment with superior performance relative to oxidative treatment during the degradation of 4-chlorophenol

Cited by 36 publications

References 17 publications

Triclosan breakdown by Fenton-like oxidation

Triclosan breakdown by Fenton-like oxidation

Comparison of reductive dechlorination of p-chlorophenol using Fe0 and nanosized Fe0

Degradation of food dyes by zero-valent metals exposed to ultrasonic irradiation in water medium: optimization and electrospray ionization mass spectrometry monitoring

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