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

Christoskova, St.; Stoyanova, M.

doi:10.1016/j.jhazmat.2008.10.051

Cited by 10 publications

(6 citation statements)

References 22 publications

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“…The pH of the solution, catalyst, samples state generally have the great impact on chemical reaction (Christoskova and Stoyanova 2009), and when varying these factors our experimental results showed different magnitudes for metasilicate release. In the water soluble experiment, the pH of the reaction solution increased to weakly alkaline because the basalt rock samples were alkaline (Chen and Zhang 1994).…”

Section: Discussionmentioning

confidence: 73%

Influences of pH and CO2 on the formation of Metasilicate mineral water in Changbai Mountain, Northeast China

Yan

Liang

Shili³

2015

Appl Water Sci

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Mineral dissolution reactions actively participate in controlling the composition of mineral water. In this study, water soluble, acidic-alkaline and carbonated solution experiments were designed, and mineral reaction mechanisms were researched using chemical kinetics and the minimum free-energy method. The results showed that the release of metasilicate was controlled by pH, CO 2 , and rock characteristics. In the water soluble experiment, the release process of metasilicate in powdered rocks reached equilibrium after 40 days, while metasilicate in solid rocks took 170 days. The release process of metasilicate in solid rocks satisfied an asymptotic model, while in powdered rocks it accorded with the Stanford reaction kinetic model. In the acidic-alkaline experiment, metasilicate was released earlier under acidic conditions (2.46 \ pH \ 7) than under alkaline conditions (7 \ pH \ 10.61). The release process of metasilicate under acidic conditions reached equilibrium in 40 days, compared with 60 days for alkaline conditions. The addition of CO 2 to the water solution was beneficial to the formation of metasilicate. Under neutral pH conditions, the reaction barely occurred. Under alkaline conditions, metasilicate was produced by the hydrolysis of metasilicate minerals. Under acidic and additional CO 2 conditions, metasilicate formation was mainly via the reaction of H ? , CO 2 , and metasilicate minerals. From these results, we concluded that the metasilicate mineral water from the Changbai Mountains, Jingyu County, is generated by a combination of the hydrolysis of metasilicate minerals and the reaction of H ? , CO 2 , and metasilicate minerals. These results can contribute to a better development and protection of the mineral water resources in the Changbai Mountains.

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Section: Discussionmentioning

confidence: 73%

Influences of pH and CO2 on the formation of Metasilicate mineral water in Changbai Mountain, Northeast China

Yan

Liang

Shili³

2015

Appl Water Sci

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“…The effluents generated during metallurgical operations, galvanizing, gold and silver extraction, crude refining, among others, contain metal complexes of cyanide or free cyanide [1]. The Environmental Protection Agency (EPA) catalogs this waste as highly dangerous for nature and human health, thus its treatment prior to discharge in water bodies is a very important issue [2]. Therefore, several methods have been applied through the years in order to oxidize cyanide to cyanate ions.…”

Section: Introductionmentioning

confidence: 99%

“…The cobalt oxides are not very efficient for the oxidation of the cyanide ion. However, the addition of another transition metal such as manganese, which has high catalytic activity, doubled the oxidation percentage [2]. If instead of a cobalt oxide, a cobalt ferrite or a nickel ferrite is used, the percentage of oxidation is 85%, which shows that the catalytic activity of the cobalt ferrite is superior to that of the oxide systems.…”

Section: Introductionmentioning

confidence: 99%

“…Due to the availability of copper, cyanide ions oxidation with these kind of ferrites makes this treatment less expensive than other conventional methods. For instance, electrochemical oxidation that demands a high energy consumption [2] and of chemical oxidation with hydrogen peroxide or peroxosulfuric acid where the reagents used are very expensive [3].…”

Section: Introductionmentioning

confidence: 99%

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Activated Carbon-Spinels Composites for Waste Water Treatment

Torre

Lozada

Adatty

et al. 2018

Metals

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Nowadays, mining effluents have several contaminants that produce great damage to the environment, cyanide chief among them. Ferrites synthesized from transition metals have oxidative properties that can be used for cyanide oxidation due to their low solubility. In this study, cobalt and copper ferrites were synthesized via the precipitation method, using cobalt nitrate, copper nitrate, and iron nitrate as precursors in a molar ratio of Co or Cu:Fe = 1:2 and NaOH as the precipitating agent. The synthesized ferrites were impregnated in specific areas on active carbon. These composites were characterized using X-Ray Diffraction (XRD) and Scanning Electron Spectroscopy (SEM). The XRD results revealed a cubic spinel structure of ferrites with a single phase of cobalt ferrite and two phases (copper ferrite and copper oxides) for copper. The CoFe2O4 impregnated on active carbon reached a cyanide oxidation of 98% after 8 h of agitation; the composite could be recycled five times with an 18% decrease in the catalytic activity. In cobalt ferrites, a greater dissolution of iron than cobalt was obtained. In the case of copper ferrite, however, the copper dissolution was higher. These results confirm that ferrites and activated carbon composites are a novel alternative for cyanide treatment in mining effluents.

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“…4 The elimination of cyanide is therefore only required when its levels exceed these thresholds. The removal of cyanide in aqueous solution by oxidation has been well studied with oxidants in the presence of various catalysts such as TiO 2 , 5 Cu( i )/Cu( ii ) transition metal complexes 6 and Fe( ii )–Cu( ii ) bimetallic complexes. 18 a Nonetheless, these systems are not “smart” enough to begin functioning under a specific set of conditions.…”

Section: Introductionmentioning

confidence: 99%

Catalyst displacement assay: a supramolecular approach for the design of smart latent catalysts for pollutant monitoring and removal

Chow

Wong

et al. 2017

Chem. Sci.

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

Cited by 10 publications

References 22 publications

Influences of pH and CO2 on the formation of Metasilicate mineral water in Changbai Mountain, Northeast China

Influences of pH and CO2 on the formation of Metasilicate mineral water in Changbai Mountain, Northeast China

Activated Carbon-Spinels Composites for Waste Water Treatment

Catalyst displacement assay: a supramolecular approach for the design of smart latent catalysts for pollutant monitoring and removal

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