Reducing degradation of azo dye by zero-valent iron in aqueous solution

Cao, Jiasheng; Wei, Liping; Huang, Qingguo; Wang, Liansheng; Han, Sang‐Ik

doi:10.1016/s0045-6535(98)00201-x

Cited by 268 publications

(172 citation statements)

References 9 publications

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“…The reduction is known to take place in the presence of Fe 0 and dilute acid [27] and the yield of the reaction is commonly less than 92 % of the theoretical amount [26,28]. The investigations of Weber [1] were performed in analogy to more recent works on the reductive degradation of organic compounds [2,4,29,30] and the 150 years old work of Béchamp was not considered. Given the possible differences in Fe 0 -H 2 O systems at pH 4 and pH 7 (e.g., contaminant speciation, kinetics of Fe 0 corrosion), Weber [1] did not explained why a reaction, which is not quantitative in industrial reactors at pH 4, should be quantitative in the environment at pH 7.2.…”

Section: The Mtw Concept and Its Limitationsmentioning

confidence: 99%

Processes of Contaminant Removal in “Fe0-H2O” Systems Revisited: The Importance of Co-Precipitation

Noubactep¹

2007

TOENVIRJ

137

107

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Abstract:The mechanism of aqueous contaminant removal by elemental iron (Fe 0 ) materials (e.g., in Fe 0 -H 2 O systems) has been largely discussed in the "iron technology" literature. Two major removal mechanisms are usually discussed: (i) contaminant adsorption onto Fe 0 oxidation products, and (ii) contaminant reduction by Fe 0 , Fe II or H/H 2 . However, a closer inspection of the chemistry of the Fe 0 -H 2 O system reveals that co-precipitation could be the primary removal mechanism. The plausibility of contaminant co-precipitation with iron corrosion products as independent contaminant removal mechanism is discussed here. It shows that the current concept does not take into account that the corrosion product generation is a dynamic process in the course of which contaminants are entrapped in the matrix of iron hydroxides. It is recalled that contaminant co-precipitation with iron hydroxides/oxides is an unspecific removal mechanism. Contaminant co-precipitation as primary removal mechanism is compatible with subsequent reduction and explains why redoxinsensitive species are quantitatively removed. Adsorption and co-precipitation precede reduction and abiotic reduction, when it takes place, occurs independently by a direct (electrons from Fe 0 ) or an indirect (electrons from Fe II /H 2 ) mechanism.

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Section: The Mtw Concept and Its Limitationsmentioning

confidence: 99%

Processes of Contaminant Removal in “Fe0-H2O” Systems Revisited: The Importance of Co-Precipitation

Noubactep¹

2007

TOENVIRJ

137

107

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“…The main absorbance region for sulfanilic acid is 258-269 nm and that for sulfanilate ion is 249 nm. Cao et al [17] studied the degradation of acid orange II dye in aqueous phase using Fe 0 system and observed reduction in the visible absorbance of reacted dye that is accompanied by wavelength shifts in UV region.…”

Section: Time Dependent Spectral Profile Transitions Ofmentioning

confidence: 99%

“…Thus the overall reaction is: [16][17][18][19][20][21][22][23][24][25][26][27]. Although Fe 0 has been applied extensively for remediation of several pollutants, the major drawbacks are slow reaction rates, rapid passivation of the metal and requirement for strict anaerobic conditions.…”

Section: Introductionmentioning

confidence: 99%

Decolourization of azo dyes using magnesium–palladium system

Patel¹,

Suresh²

2006

Journal of Hazardous Materials

117

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“…[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. [19][20][21][22][23][24][25][26][27][28][29] Mass spectrometry (MS) has been used for a long time for the measurement of isotopes and to determine the structure of organic molecules.…”

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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Reducing degradation of azo dye by zero-valent iron in aqueous solution

Cited by 268 publications

References 9 publications

Processes of Contaminant Removal in “Fe0-H2O” Systems Revisited: The Importance of Co-Precipitation

Processes of Contaminant Removal in “Fe0-H2O” Systems Revisited: The Importance of Co-Precipitation

Decolourization of azo dyes using magnesium–palladium system

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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