Aqueous phase catalytic oxidation of cyanides over iron-modified cobalt oxide system

Stoyanova, M.; Christoskova, St.; Georgieva, M.

doi:10.1016/j.apcata.2004.06.002

Cited by 11 publications

(7 citation statements)

References 27 publications

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“…These results support the assumption that the active oxygen of the catalyst is directly involved in the oxidation of cyanide, while the oxygen from air re-oxidizes the partially reduced surface of the catalyst. Data obtained confirms the results of our previous investigation concerning the liquid phase oxidation of cyanide over Co-Fe oxide catalyst prepared by the same method [21] as well as the results of other authors [31,32]. The influence of both catalyst concentration and pH of the medium on the cyanide conversion efficiency was investigated.…”

Section: Catalytic Activity and Reaction Selectivitysupporting

confidence: 80%

“…Moreover, some leaching of the catalysts in the course of cyanide catalytic oxidation occurred, which is a drawback for the practical application of these catalytic systems and further treatment to remove toxic nickel and cobalt ions from the water are needed. The modification of an individual Co oxide system with iron resulted in a more active catalyst with high selectivity to carbon dioxide even in alkaline medium [21]. Keeping in mind that most of the waste waters containing cyanide were being subjected to detoxification under alkaline conditions, the iron modified Co-oxide system appears to be promising for applications in the field of the abatement of cyanide in waste waters.…”

Section: Introductionmentioning

confidence: 99%

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Novel Ni−Fe-oxide systems for catalytic oxidation of cyanide in an aqueous phase

Stoyanova

Christoskova

2005

Open Chemistry

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Catalytic activity of mixed Ni-Fe oxide systems with respect to air oxidation of aqueous cyanide solution at 308 K was investigated. The catalysts employed were prepared by an oxidation-precipitation method at room temperature and were characterized by powder Xray diffraction (XRD), Mössbauer spectroscopy, and chemical analysis. The cyanide oxidation rate was found to be dependent on the catalyst's calcination temperature, pH of the medium, and catalyst loading. Results revealed that the catalyst calcined at 120 • C is the most active where up to 90 % of free cyanide (4 mM) was removed after oxidation for 30 minutes in the presence of 2.5 g/L catalyst at pH 9.5. The cyanide conversion becomes less favorable as the pH of the solution increases (with other constant parameters). The selectivity data showed that carbon dioxide is the main oxidation product, regardless of pH of the solution.

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Section: Catalytic Activity and Reaction Selectivitysupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Novel Ni−Fe-oxide systems for catalytic oxidation of cyanide in an aqueous phase

Stoyanova

Christoskova

2005

Open Chemistry

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“…Based on this reason only few catalytic systems used for the low-temperature complete oxidation of cyanides are described in the literature [16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Catalytic oxidation of cyanides in an aqueous phase over individual and manganese-modified cobalt oxide systems

Christoskova¹,

Stoyanova²

2009

Journal of Hazardous Materials

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“…Óxidos semiconductores han sido empleados para la remoción fotocatalí-tica de cianuro libre [19], [20], [21], pero aun sigue siendo ampliamente usado el T iO 2 [8], [22], [23], [24] : sin embargo sistemas basados en oxido de niobio hidratado han mostrado ser potencialmente útiles para oxidar ion cianuro a ion cianato y aniones inorgánicos como amonio y nitratos [25], [26], [27]. El propó-sito de esta investigación, fue realizar un análisis comparativo de la influencia del tipo de agente oxidante en la degradación de cianuro libre, utilizando como catalizador el óxido de titanio Deggusaa P-25 y pentóxido de niobio hidratado, con muestras preparadas en el laboratorio y empleando como agentes oxidantes…”

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Estudio catalítico comparativo de los sistemas TiO2 y Nb2O5 en la degradación de cianuro en función del tipo de oxidante

López

Sierra

2012

ing.cienc.

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La viabilidad del uso de otros agentes fotocatalizadores como el niobio, radicaen disminuir las energías altas de la banda prohibida para hacerlo competitivo frente al TiO2, sin embargo la presencia de coayudantes de oxidación, talescomo H2O2 y O3 podrían presentar resultados sorprendentes en el desempeño catalítico, debido a una mayor generación del radicales OH. La obtención de óxidos de mayor área y propiedades texturales diferentes al oxido de niobio comercial, mejoran su actividad catalítica en la remoción de cianuro libre. El trabajo presenta resultados experimentales de fotodegradación de cianuro 100mg=l sobre TiO2 Degussa P- 25 y Nb2O5 · 3H2O, usando un fotorreactor CPC con una capacidad de 4L de solución, usando como fuente de radiación la luz solar, tomando una inclinación igual a la latitud de Cartagena 10.45°, los resultados indicaron un claro efecto del pH, el tipo de catalizador y el coayudante de oxidación. La reducción de ion cianuro del efluente contaminado aumento por la adición del agente oxidante (O3 y H2O2). Sugiriendo una mayor susceptibilidad del cianuro libre, para oxidarse a cianato de forma indirecta, por una mayor generación de radicales hidroxilos, inducidos por la presencia de H2O2 o del O3 bajo radiación solar. Se obtuvo porcentajes de oxidación fotocatalítica de cianuro libre, entre el 64% y 72% usando Nb2O5 · 3H2O y un rango entre 67% y 71% usando TiO2 Degussa P - 25. Los catalizadores fueron caracterizados estructuralmente usando DRX, BET,Raman e FT-IR, con la finalidad de correlacionar los cambios morfológicos con el desempeño catalítico.

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Aqueous phase catalytic oxidation of cyanides over iron-modified cobalt oxide system

Cited by 11 publications

References 27 publications

Novel Ni−Fe-oxide systems for catalytic oxidation of cyanide in an aqueous phase

Novel Ni−Fe-oxide systems for catalytic oxidation of cyanide in an aqueous phase

Catalytic oxidation of cyanides in an aqueous phase over individual and manganese-modified cobalt oxide systems

Estudio catalítico comparativo de los sistemas TiO2 y Nb2O5 en la degradación de cianuro en función del tipo de oxidante

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