X‐ray photoelectron study of surface compounds formed during flotation of minerals

Нефедов, В. И.; Salyn, Ya. V.; Solozhenkin, P. M.; Pulatov, G. Yu.

doi:10.1002/sia.740020503

Cited by 117 publications

(66 citation statements)

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“…The reactants were interacted in solid state. The observations are given bellowThe scheme may follow the following route MSO 4 and Hg 2+ ions in solid state as well as solution [13] has been undertaken. Their structures have been established by XRD pattern.…”

Section: Resultsmentioning

confidence: 99%

“…The final products were purified through vigorous washing with distilled water for several times. The final washing was completed with the removal of SO 4 2-, S 2-and Cl -ions. Nanoparticles of ZnS, CdS and HgS were stabilized by ethylene glycol reducing agent.…”

Section: Methodsmentioning

confidence: 99%

“…Such transitions [1][2][3][4][5][6][7] in UV -Visible spectrum of oxidation charge transfer type [2]. CdS is widely used as photo detector in visible spectrum.…”

Section: Introductionmentioning

confidence: 99%

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Interaction of Sodium Sulfide with Zn2+, Cd2+ and Hg2+ ions in Presence of Sun – light and Preparation of Nanoparticles in Ethylene glycol

Gupta¹

2014

IOSRJAC

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Interaction of Sodium Sulfide with Zn2+, Cd2+ and Hg2+ ions in Presence of Sun – light and Preparation of Nanoparticles in Ethylene glycol

Gupta¹

2014

IOSRJAC

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“…If CuS was a significant surface compound, a S 2p peak at about 162.6 -162.7 eV would be expected (Brion 1980, Perry and. According to published data, the BE range for Cu in CuS is broad, ranging from 931.8 eV (Bhide et al 1981) to as high as 935.0 eV (Nefedov et al 1980), thus requiring the existence of a corresponding S 2p peak to confirm its presence, which is not found here.…”

mentioning

confidence: 89%

“…Again, the existence of these compounds is not supported by the Cu spectrum, where a Cu 2p3/2 spectrum around 935 eV for CuS (Nefedov et al 1980), and 935.1 eV for Cu(OH)2 (McIntyre et al 1981) would be expected. Metal-deficient sulfide or disulfide may be considered, and these species have been identified at about 162 eV ) but this may be too low in BE to represent the S 2p species detected here.…”

Section: Surface Species Of Oxidized Enargite At Peak 1 (+347 Mv)mentioning

confidence: 99%

Investigation of the surface species formed on enargite in electrochemically controlled oxidising environments and in the presence of flotation collectors

Plackowski¹

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Arsenic sulphides such as enargite and tennantite can represent significant penalty elements in base metals production. There are significant economic advantages to achieving a separation of arsenic bearing minerals at an early stage in processing, but to date no feasible widely applicable commercial method of flotation separation has been developed. A review of the existing literature on the selective flotation of enargite considered its surface properties and floatability. Special consideration was given to the various approaches in the study of enargite surface chemistry, and the implications for the flotation of enargite. Developments in these approaches were critically reviewed and discussed.The surface oxidation and hydrophobicity of natural enargite (Cu3AsS4) and the formation of oxidation species at the mineral surface were examined by a novel experimental approach that combines electrochemical techniques and atomic force microscopy (AFM). Combined with ex situ cryo X-ray photoelectron spectroscopy (XPS), the surface speciation of oxidised enargite was obtained, and compared with the newly fractured natural enargite surface.At pH 4, surface layer formations consisting of metal-deficient sulphide and elemental sulphur were identified, associated with a limited increase in root-mean-square (rms) roughness (1.228 to 3.143 nm) and an apparent heterogeneous distribution of surface products as demonstrated by AFM imaging. A mechanism of initial rapid dissolution of Cu followed by diffusion-limited surface layer deposition was identified.At pH 10, a similar mechanism was identified although the differences between the initial and diffusion-limited phases were less definitive. Surface species were identified as copper sulphate and hydroxide. A significant increase in surface rms roughness was found (0.795 to 9.723 nm). Dynamic (receding) contact angle measurements obtained by a droplet evaporation method found no significant difference between the oxidised surface and a freshly polished surface. A significant difference was found between the polished surface and that oxidized at pH 4, with an increase in contact angle of about 13° (46° to 59°) after oxidation. Competing effects of hydrophilic and hydrophobic species on the mineral surface under oxidizing conditions at pH 4 and the change in surface roughness at pH 10 may contribute to the observed effects of electrochemically controlled oxidation on enargite hydrophobicity.The effects of X-ray radiation on the surface after electrochemical oxidation were investigated using XPS. Surface species present on unoxidized enargite were compared with those present after oxidation at pH 10, and the effects of X-ray irradiation time as a ii function of temperature were studied. XPS spectra characteristic of a copper (II) hydroxide surface layer reduced in intensity with increasing X-ray exposure time. Associated changes in the relative concentrations of surface oxygen species were also observed.Temperature was shown to significantly influence the rate of change. A...

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Confined Fe–Cu Clusters as Sub‐Nanometer Reactors for Efficiently Regulating the Electrochemical Nitrogen Reduction Reaction

et al. 2020

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Ammonia is traditionally an essential chemical for fertilizers and other nitrogencontaining products that have been supporting most of the world population for over a century. Recently, ammonia is receiving renascent attentions as a potential hydrogen storage medium and carbon-free fuel, due to its advantages of easy liquefication to achieve a higher volumetric energy density and more facile transportation as compared with other gas-based fuels. [1] Conventionally, the industry-scale production of ammonia, based on the Habor-Bosch method through a nitrogen reduction reaction (NRR), is high-cost, energy-intensive, and environmentally unfriendly, as it not only consumes a large amount of fossil energy but also is associated with the release of Electrochemical nitrogen reduction reaction (NRR) over nonprecious-metal and single-atom catalysts has received increasing attention as a sustainable strategy to synthesize ammonia. However, the atomic-scale regulation of such active sites for NRR catalysis remains challenging because of the large distance between them, which significantly weakens their cooperation. Herein, the utilization of regular surface cavities with unique microenvironment on graphitic carbon nitride as "subnano reactors" to precisely confine multiple Fe and Cu atoms for NRR electrocatalysis is reported. The synergy of Fe and Cu atoms in such confined subnano space provides significantly enhanced NRR performance, with nearly doubles ammonia yield and 54%-increased Faradic efficiency up to 34%, comparing with the single-metal counterparts. First principle simulation reveals this synergistic effect originates from the unique Fe-Cu coordination, which effectively modifies the N 2 absorption, improves electron transfer, and offers extra redox couples for NRR. This work thus provides new strategies of manipulating catalysts active centers at the sub-nanometer scale.

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X‐ray photoelectron study of surface compounds formed during flotation of minerals

Cited by 117 publications

References 3 publications

Interaction of Sodium Sulfide with Zn2+, Cd2+ and Hg2+ ions in Presence of Sun – light and Preparation of Nanoparticles in Ethylene glycol

Interaction of Sodium Sulfide with Zn2+, Cd2+ and Hg2+ ions in Presence of Sun – light and Preparation of Nanoparticles in Ethylene glycol

Investigation of the surface species formed on enargite in electrochemically controlled oxidising environments and in the presence of flotation collectors

Confined Fe–Cu Clusters as Sub‐Nanometer Reactors for Efficiently Regulating the Electrochemical Nitrogen Reduction Reaction

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