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Electrocatalytic alkyne semi-hydrogenation to alkenes with water as the hydrogen source using a low-cost noble-metal-free catalyst is highly desirable but challenging because of their over-hydrogenation to undesired alkanes. Here, we propose that an ideal catalyst should have the appropriate binding energy with active atomic hydrogen (H*) from water electrolysis and a weaker adsorption with an alkene, thus promoting alkyne semi-hydrogenation and avoiding over-hydrogenation. So, surface sulfur-doped and -adsorbed low-coordinated copper nanowire sponges are designedly synthesized via in situ electroreduction of copper sulfide and enable electrocatalytic alkyne semi-hydrogenation with over 99% selectivity using water as the hydrogen source, outperforming a copper counterpart without surface sulfur. Sulfur anion-hydrated cation (S2−-K+(H2O)n) networks between the surface adsorbed S2− and K+ in the KOH electrolyte boost the production of active H* from water electrolysis. And the trace doping of sulfur weakens the alkene adsorption, avoiding over-hydrogenation. Our catalyst also shows wide substrate scopes, up to 99% alkenes selectivity, good reducible groups compatibility, and easily synthesized deuterated alkenes, highlighting the promising potential of this method., Highly selective electrocatalytic semi-hydrogenation of alkynes over a noble-metal-free catalyst is highly desirable. Here, authors synthesize sulfur-containing copper nanowire sponges for selective electrocatalytic alkyne semi-hydrogenation using water as the hydrogen source.

The structure and phase composition of synthesized copper(I) sulfide are studied. It is shown that, both chalcocite (Cu2S) and jarleite (Cu31S16) phases can form in the copper sulfide crystallization. Jarleite is characterized by a deficit of copper in the crystal lattice and a deviation from the stoichiometric composition. The formation of jarleite is associated with the crystallization of the copper metal phase. The crystal lattice parameters of the synthesized phases are calculated. It is shown that they correlate with the database of International Center for Diffraction Data. The electrochemical oxidation of specimen in the sulfuric acid solution is carried out. It is found that at a current density of 1000 A/m2 and a concentration of 100 g/dm3 H2SO4, the electrochemical dissolution of copper sulfide proceeds with the formation of passive film of slightly soluble products due to the oxidation of copper(I) sulfide to copper(II) sulfide. In addition, in the course of oxidation, intermediate nonstoichiometric sulfides (Cu1.74S, Cu1.8S, Cu1.6S, and CuS) form in the following order: Сu2S (Cu31S16) → Cu1.8S → Cu1.74S → Cu1.6S → CuS → S + Cu2+. The process is accompanied by the transition of copper cations into the solution. As elemental sulfur and copper sulfides are accumulated on the specimen reactive surface, the electrochemical oxidation rate decreases due to slow removal of the products and slow supply of the reagent to the reaction zone.

Among metals used for CO2 electroreduction in water, Cu appears to be unique in its ability to produce C2+ products like ethylene. Bimetallic combinations of Cu with other metals have been investigated with the goal of steering selectivity via creating a tandem pathway through the CO intermediate or by changing the surface electronic structure. Here, we demonstrate a facile cation exchange method to synthesize Ag/Cu electrocatalysts for CO2 reduction using Cu sulfides as a growth template. Beginning with Cu2−xS nanosheets (C-nano-0, 100 nm lateral dimension, 14 nm thick), varying the Ag+ concentration in the exchange solution produces a gradual change in crystal structure from Cu7S4 to Ag2S, as the Ag/Cu mass ratio varies from 0.3 to 25 (CA-nano-x, x indicating increasing Ag fraction). After cation exchange, the nanosheet morphology remains but with increased shape distortion as the Ag fraction is increased. Interestingly, the control (C-nano-0) and cation exchanged nanosheets have very high faradaic efficiency for producing formate at low overpotential (−0.2 V vs. RHE). The primary effect of Ag incorporation is increased production of C2+ products at −1.0 V vs. RHE compared with C-nano-0, which primarily produces formate. Cation exchange can also be used to modify the surface of Cu foils. A two-step electro-oxidation/sulfurization process was used to form Cu sulfides on Cu foil (C-foil-x) to a depth of a few 10 s of microns. With lower Ag+ concentrations, cation exchange produces uniformly dispersed Ag; however, at higher concentrations, Ag particles nucleate on the surface. During CO2 electroreduction testing, the product distribution for Ag/Cu sulfides on Cu foil (CA-foil-x-y) changes in time with an initial increase in ethylene and methane production followed by a decrease as more H2 is produced. The catalysts undergo a morphology evolution towards a nest-like structure which could be responsible for the change in selectivity. For cation-exchanged nanosheets (CA-nano-x), pre-reduction at negative potentials increases the CO2 reduction selectivity compared to tests of as-synthesized material, although this led to the aggregation of nanosheets into filaments. Both types of bimetallic catalysts are capable of selective reduction of CO2 to multi-carbon products, although the optimal configurations appear to be metastable.

An understanding of the fundamentals of the reaction between CuO with trace amounts of H2S to form CuS products is critical for the optimal utilization of this process in sulfur removal applications. Unfortunately, CuS is a complex material, featuring various Cu2-xS compounds (with 0 ≤ x ≤ 1), distorted crystal phases, and varying electronic structures and coordination environments of Cu and S ions. In this work, we combine ex situ and in situ X-ray absorption spectroscopy (XAS) at S and Cu K edges, fixed bed sorption experiments, DFT simulations, and other characterization techniques to speciate the CuS products formed at different temperatures (298-383 K) and from CuO sorbents with different crystallite sizes (2.8-40 nm). The results of our analysis identify the formation of a distorted CuS layer at the surface of CuO crystals with disulfide groups with shorter Cu-S bonds and higher delocalization of the positive charge of the Cu center into (S1-)2. This distorted CuS layer dominates the XAS signal at lower temperatures (298-323 K) and at the initial stages of sulfidation at higher temperatures (353 and 383 K) where conversion is low (

Electrochemical hydrogen evolution reaction (HER) using non-precious compounds has gained substantial interest in the development of water electrolyzers. Herein, we report the synthesis of Copper sulfide (Cu2S) micro-hexagons via a hydrothermal method, followed by some of the important physiochemical characterizations and electrochemical measurements towards the HER. Cu2S micro-hexagons could catalyze the HER in both basic (1 M KOH) and acidic solutions (0.5 M H2SO4), corresponding to the extreme pH values of 14 and 0, respectively. As manifested from the polarization curve, Cu2S micro-hexagons required an overpotential of −330 mV and −312 mV to deliver a benchmark catalytic current density of 10 mA cm−2 in basic and acidic solutions, respectively. Furthermore, lower overpotentials are complemented with the prominent long-term stability of 24 h, as evident from chronopotentiometric analysis. The superior electrochemical performance of these Cu2S micro-hexagons demonstrates their promising suitability for water-splitting applications.

A ternary mixture of carbon, copper sulfide, and cobalt sulfide was used to fabricate the counter electrode (CE) in quantum-dot-sensitized solar cells (QDSSCs). The ternary-mixture-based CE achieve...

BACKGROUND Significant efforts have been devoted to examine the adsorption of flotation surfactants in both mechanistic studies and process implementations. However, quantitative electrochemical methods for flotation surfactant adsorption examination have not been well-established, despite of their low-cost, accurate, in-situ nature.RESULTS In this paper, voltametric measurement was proven to quantitatively examine the adsorption of activating copper and lead ions onto a pyrite surface. The activation was achieved by abrading minerals in a heavy-metal-bearing solution and the measurements were performed by transferring the minerals to a solution free of those heavy metals. This provided a simple but realistic simulation of the mineral grinding process and simplified the adsorption quantification by excluding any other irrelevant electrochemical reactions near the surface. Reliable electrochemical impedance spectroscopy (EIS) upon adsorption with convincing physical models for interpreting the interfacial structures also were obtained in this paper. The additional pseudocapacitive behaviour of the copper sulfide surface layer led to an increased capacitance of the measured EIS. A resistive but ion-permeable xanthate adsorption layer exhibited its own relaxation process. Voltammetry and impedance studies showed that cyanide competed with both copper and lead for their adsorption, whereas lead activation showed greater tolerance to cyanide than copper did.CONCLUSION Electrochemical methods have been established to examine the adsorption of copper, lead and xanthate onto pyrite surface, in relation to various flotation conditions, which exhibited significant implication to the flotation of pyritic gold ore using cyanide-bearing water. (c) 2020 Society of Chemical Industry

The behavior of nickel sulfide (Ni3S2), copper sulfide (Cu2S), and their mixture (Ni3S2 : Cu2S = 1 : 1) is studied under the leaching conditions in sulfuric acid solutions. The effects of the acid concentration, the temperature, and the leaching time on the dissolution kinetics and the phase compositions of the leaching residues of nickel sulfide Ni3S2 and the sulfide mixture are determined. The degrees of extraction of copper and nickel to the solution during the leaching of the individual sulfides and their mixture are compared. Only nickel passes to a solution upon the leaching of the mixture of the sulfides, and copper is absent from the solution until the complete dissolution of nickel sulfide.

The corrosion behavior of copper electrode in unpolluted and sulfide polluted synthetic seawater (SSW) was carried out. It was demonstrated that the coexistence of sulfide and dissolved dioxygen in seawater leads to an increase in the anodic and cathodic current densities. However, the addition of chitosan polymer as corrosion inhibitor resulted in a significant decrease in the anodic as well as cathodic current densities. The immersion of copper sample in the sulfide-polluted seawater resulted in the formation of a copper sulfide layer on the metal surface. It was observed that the copper sulfide formed on copper foam immersed in sulfide-polluted seawater affects the oxygen reduction reaction (ORR) and, therefore, the entire corrosion mechanism. The copper sulfide film was also obtained on the copper electrodes following electrodeposition method (chronoamperometry). The deposited film increased the diffusion-limiting current suggesting the diffusion-controlled mechanism of the ORR. The presence of chitosan decreased the current density and the rate of oxygen reduction in the synthetic seawater solution. Keywords: Catalytic activity, Corrosion inhibition, Oxygen reduction, Cathodic reaction, Sulfide polluted synthetic seawater, Electrodeposition

We have investigated the chemical bath deposition (CBD) of CuS using thioacetamide on functionalized self-assembled monolayers (SAMs) using scanning electron and optical microscopies, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry. For all SAMs studied, the amount of CuS deposited is strongly dependent on the bath pH and can be attributed to the interaction of the SAM terminal groups with the chalcogenide ions present in solution. For -CH3-terminated SAMs, there is a steady increase in the amount of CuS deposited with an increase in the bath pH because there is an increase in the concentration of chalcogenide ion. However, for -OH- and -COOH-terminated SAMs, we observe that the maximum amount of CuS is deposited at pH 10. We attribute this behavior to a competition between the repulsion of the chalcogenide ions by the negatively charged SAM terminal groups and an increase in the chalcogenide ion concentration with an increase in the bath pH. Using the interaction of the chalcogenide ions with the different SAM terminal functional groups, we demonstrate that CuS can be selectively deposited on the -CH3-terminated areas of patterned -OH/-CH3- and -COOH/-CH3-terminated SAMs.

Well-controlled core–shell nanostructured arrays are highly attractive and rational combination of hybrid electrochemical active materials as promising candidate electrodes for supercapacitors still remains a great challenge. In this work, ultrathin Ni(OH)2 nanosheets as the “shell” were anchored on Cu7S4 nanorods as the “core” to form core–shell hybrid nanoarrays on copper foam (CF), which were firstly fabricated by a facile metal–organic framework templated synthetic strategy with a three-step procedure of in situ interface growth, sulfurization and hydrothermal synthesis. The core–shell Cu7S4@Ni(OH)2/CF hybrid nanoarrays as binder-free electrodes show a high specific capacitance of 1072.5 F g−1 (482.6 C g−1) at a current density of 1 A g−1, superior rate capacity of 86.4% at 10 A g−1 and an outstanding cycling stability of 94.5% capacitance retention after 10 000 cycles. What's more, the assembled asymmetric supercapacitor device based on Cu7S4@Ni(OH)2/CF as a positive electrode and activated carbon (AC) as a negative electrode shows a high energy density of 52.5 W h kg−1 at a power density of 750 W kg−1 with decent cycling stability. This strategy can be extended to form other unique copper sulfide-based core–shell nanoarray architectures with enhanced electrochemical activity for high-performance energy storage devices.

The synthesis and characterization of two novel copper and nickel coordination compounds with 2-aminobenzothiazole is reported. The crystals were obtained after adding solid 2-aminobenzothiazole to a methanol solution of Cu(CH3COO)2·H2O and after adding a methanol solution of Ni(CH3COO)2·4H2O to a methanol solution of 2-aminobenzothiazole. The products were characterized using single-crystal X-ray diffraction analysis, infrared spectroscopy and thermal analysis. The crystals of the compound bis(acetato-O)-bis(2-aminobenzothiazole-N)-copper(II), [Cu(O2CCH3)2(C7H6N2S)2] (1) and colorless crystals of bis(acetato-O)-bis(2-aminobenzothiazole-N)-nickel(II), [Ni(O2CCH3)2(C7H6N2S)2] (2) are stable in air. Non–covalent interactions including intra- and inter-molecular hydrogen bonds in both crystal structures are discussed along with the Jahn-Teller effect of the structures. Both of the compounds are acting as single-source precursors of nanostructured metal sulfides. Namely, thermal analysis showed that the final product of heating compound 1–600 °C is nanocrystalline copper sulfide, Cu9S5, while the final product of heating compound 2–1100 °C is nickel sulfide, Ni3S2.

The removal of arsenic from base-metal ores is an important environmental objective, especially in relation to mineral processing. Herein, we report an investigation into the adsorption performance of copper ions on arsenopyrite surfaces and implications for flotation using local electrochemical impedance and X-ray photoelectron spectroscopies, time-of-flight secondary ion mass spectrometry, zeta-potential measurements, and microflotation experiments. We show that the electrochemical impedance and degree of oxidation of the arsenopyrite decreases as Cu2+ is adsorbed onto the arsenopyrite surface, and copper species remain on the surface in the form of Cu(I) following treatment with Cu2+, while Cu2+ improves the surface charge of the arsenopyrite. A heterogeneously distributed Cu signal appears in the X-ray photoelectron spectrum of the arsenopyrite sample treated with Cu2+ ions, and copper in the form of copper sulfide remains on the mineral surface. Microflotation experiments reveal that the low floatability of arsenopyrite in alkaline environments is improved by treatment with Cu2+.

Chalcopyrite is the most abundant but also the most recalcitrant copper sulfide mineral in leaching processes. The reasons for its refractory character are passivation and/or its semi-conductive properties. In our study chalcopyrite was hydrometallurgically processed via chemical leaching, electrochemical leaching, bioleaching and electrobioleaching in 2 l stirred tank laboratory experiments. Both biotic leaching treatments were more successful than both abiotic leaching experiments, however, overall the copper recovery was low due to the recalcitrant character of chalcopyrite. Various electrochemical techniques such as cyclic voltammetry, potentiodynamic polarization and electrochemical impedance spectroscopy were applied to investigate the differences in surface properties of the residues. Potentiodynamic polarization and cyclic voltammetric studies showed that any kind of leaching resulted in increased dissolution resistance and surficial redox inactivation compared to unprocessed chalcopyrite. However, if chalcopyrite was continuously in direct contact to the cathodic working electrode its surface was activated and showed even the highest oxidation currents which implicates increased leachability. Thus, at the surface of such chalcopyrite particles the mineral was converted into readier leachable minerals such as chalcocite. Additionally, electrochemical impedance spectroscopy (EIS) was carried out in the presence of ferrous and ferric iron. It turned out that surface activation via ferrous iron was not observed. In contrast, ferric iron led to successive passivation over time. The charge transfer resistance was the lowest for unprocessed and surface reduced chalcopyrite and the highest for chemically and electrochemically leached sulfide mineral. The findings of this comparative, electrochemical study support that passivation takes place to larger extend during abiotic leaching (chemical and electrochemical leaching) compared to biotic leaching (bioleaching and electrobioleaching).

The effect of sulfide concentration on the corrosion and cavitation erosion behavior of a cast manganese-aluminum bronze (MAB) alloy in 3.5% NaCl solution was investigated. The electrochemical results showed that when the sulfide concentration exceeded 50 ppm, hydrogen evolution reaction dominated the cathodic process because of the very negative corrosion potential of MAB, and the formation of a copper sulfide film on MAB was a diffusion-controlled process. The mass loss rate of MAB after longer-term immersion was ordered by the sulfide concentration as: 20/50 ppm > 100 ppm > zero > 200 ppm. In the 200 ppm sulfide solution, the mass loss rate of MAB was the lowest, because of the formation of a thin and homogeneous copper sulfide film. In the other sulfide solutions, the formation of a less-protective film with both oxides and sulfides resulted in higher mass loss rate of MAB. Moreover, selective phase corrosion occurred at the β and κ phases in solutions with sulfide addition less than 100 ppm. For all solutions, it was the mechanical attack that dominated cavitation erosion degradation. The cavitation erosion–corrosion synergy was lower in high sulfide solutions, because the corrosion products on MAB could reduce the mechanical impact under cavitation erosion.

Malachite is depressed during sulfidization flotation when excess sodium sulfide is added to it. Thus, this study investigated the role and mechanism of ammonium sulfate as a sulfidization promoter for eliminating the depression of excess S2− via micro-flotation experiments, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM-EDS), and inductively coupled plasma mass spectrometry (ICP-MS). Micro-flotation experiments revealed that malachite changed from a non-floating state to an easily floating state by (NH4)2SO4 addition prior to sulfidization with xanthate as the collector. The solution chemical reactions involving (NH4)2SO4 are the key to re-floating malachite. The surface properties of malachite were changed by (NH4)2SO4, and these changes enhanced its flotation behavior. However, (NH4)2SO4 was not adsorbed onto the malachite surface in any form, as confirmed by the XPS analysis. (NH4)2SO4 has a dissolution on the malachite surface, causing lattice imperfections, which, in turn, provided the conditions necessary for subsequent adsorption of Cu(NH3)n2+, S2− (SH−), and Cu2+ on the malachite surface. Consequently, a layer or multilayer copper sulfide hydrophobic film formed on the malachite surface. Even the low-activity cylindrical surface of malachite was also covered with a stable copper sulfide film, resulting in improved malachite flotation in the presence of excess Na2S.

Fast, selective, and effective enrichment is critical for onsite detection and online monitoring of extremely low-concentration toxic heavy metal ions in complex environmental samples. In the current work, varied CuS nanostructures (hollow nanospheres, nanoflowers, nanoparticles) were prepared and applied to the enrichment of Hg(II) ions. Surprisingly, the as-prepared CuS nanostructures exhibited unprecedented ultrahigh selectivity and rapid uptake toward Hg(II) ions in the presence of other seven metal ions, suggesting specificity of mercury enrichment by the CuS nanostructures. Upon treating a 100 mL aqueous sample containing 8 different metal ions with only 10 mg of CuS hollow nanospheres, over 99.5% of Hg(II) ions could be removed within just 1 min, achieving a final Hg(II) ion level down to 0.1 ppb. This excellent selectivity was well accounted for by the Hard Soft Acid Base theory and especially the solubility product constant, where the solubility product constant of CuS is higher than that of HgS but lower than that of sulfides of other interfering metal ions. The current results are striking and would open a new avenue to the search for highly selective and efficient absorptive nanomaterials toward varied heavy metal ions.

Anisotropic nanoparticles exhibit interesting properties and their controlled assemblies are highly desirable to generate functional materials. Different from their spherical counterparts, the incorporation of anisotropic nanoparticles in nanostructured polymeric matrices such as block copolymer or supramolecules depends not only on the particle/polymer interactions and relative size ratio between the particle and polymer features but also on the interparticle interactions. Here, we fill this knowledge gap by systematically studying the block copolymer-based supramolecular nanocomposite containing anisotropic copper sulfide nanodiscs, and evaluate the effect of competition between the ligand–polymer interaction and internanodisc interaction on the arrangement and interparticle spacing of nanodiscs once blended with supramolecules. The interdisc interaction was modulated by varying the ligand density and/or the ligand shell thickness on the surface of nanodiscs. Reduction in the interdisc interaction leads...

The azide-alkyne cycloaddition (Huisgen reaction) is one of the most powerful and widely used copper-mediated reactions. In many such reactions, use of metal or metal oxide nanoparticles as the catalyst is more appealing because of the increased catalytic activity attributed to the large surface to volume ratio. However, the nano/micro particles are synthesized often in the presence of long chain organic molecules as capping or stabilizing agents. These organic molecules cover the active centers and restrict or reduce their catalytic activity. Therefore, we have synthesized the copper sulfide (sf-CuS) nano/micro particles without having organic surfactant molecules as the capping agent. These particles with a flower-like architecture (micro flowers, mf) were obtained readily under the supersaturated condition at room temperature. In these particles, the surface was freely available for adsorption and desorption reactions. When utilized as a catalyst in multicomponent cycloaddition reactions, the sf-CuS mf exhibited excellent catalytic activity compared with some other nanoparticles with surfactants. This sf-CuS mf catalyzed the one-pot synthesis of 1,2,3-triazole and β-hydroxy-1,2,3-triazole effectively from a variety of benzyl bromide derivatives epoxides respectively. Both these reactions proceeded in the presence of azide and phenylacetylene in the water at room temperature. The catalyst was reusable, and there was no catalyst leaching observed during reactions. Synthesis of β-hydroxy triazoles and 1,2,3-triazoles under exceptionally mild conditions with high yields proved the sf-CuS mf as the catalyst as a robust and recyclable catalyst.

Flotation processing of copper-pyrite ores is accompanied by the formation of flotation tailings containing 0.2-0.7 % wt Cu and 0.6-1.4 g/t Au. Deeper extraction of these components into commercial products is of practical interest. The possibility of additional recovery of copper and gold using the example of tailings from the current processing of PJSC “Gaysky GOK” was studied. It was shown that thin emulsion impregnation of chalcopyrite (less than 10 μ) in pyrite prevented the copper and gold from being extracted from the tailings by ore dressing methods. A scheme for the deep extraction of valuable components, based on the preliminary concentration of gold and copper by pyrite flotation, was proposed. About 84.5% of gold and 60.9% of copper were extracted into pyrite concentrate, while the gold content in the chamber product was 0.25 g/t. The increase in the extraction of copper was impossible due to nature of copper phase in chamber product that consisted mainly of copper oxides. Further processing of the pyrite concentrate can be accomplished by the way based on oxidative roasting (550-600 °C), with subsequent sulfuric acid leaching of copper from the calcine, washing and cyanidation of washed cake. Acid leaching is recommended to be done without external heating with solutions of 10-20 g/l of sulfuric acid. Copper was precipitated from leachates by cementation with iron powder in the form of copper concentrate (22-32 % wt Cu), then the gold-containing solution is processed to produce ligature gold. The optimal conditions for the cyanidation of the calcine were determined as follows, L:S = 2, the initial concentration of NaCN was 2 g/l, the duration of cyanidation was 2 hours The possibility of achieving end-to-end extraction of 66% of gold, and 45% of copper in commercial products is shown. The proposed scheme makes it possible to reduce the specific consumption of NaCN during cyanidation from 2.5-2.8 to 0.8 kg/t of tailings. It is assumed to gain sulfuric acid from the burning gases.

Mineral sulfide based sorbents were superior alternatives to traditional activated carbons for elemental mercury (Hg0) immobilization in industrial flue gas. A systematical study concerning the influence of sulfur trioxide (SO3) on Hg0 adsorption over a nanosized copper sulfide (Nano-CuS) was for the first time conducted. SO3 was found to significantly inhibit the Hg0 removal over Nano-CuS partially because SO3 oxidized the reduced sulfur species (sulfide) with high affinity to mercury to its oxidized sulfur species (sulfate). Moreover, a brand new "oxidation-reduction" mechanism that led to a simultaneous oxidation of sulfide and reduction of mercury on the immobilized mercury sulfide (HgS) was responsible for the inhibitory effect. Even though the released Hg0 from the reduction of mercury in HgS could be oxidized by SO3 into its sulfate form (HgSO4) and recaptured by the sorbent, the "oxidation-reduction" mechanism still compromised the Hg0 capture performance of the Nano-CuS because HgSO4 deposited on the sorbent surface could be easily leached out when environmentally exposed. These new insights into the role of SO3 in Hg0 capture over Nano-CuS can help to determine possible solutions and facilitate the application of mineral sulfide sorbents as outstanding alternatives to activated carbons for Hg0 immobilization in industrial flue gas.

Copper sulfide (CuS) has been proved to be a potential alternative to traditional sorbents for control of elemental mercury (Hg0) emissions downstream of the wet flue gas desulfurization (WFGD) systems. However, the detailed reaction mechanisms involved in Hg0 adsorption over CuS surface are still unclear. The density functional theory was applied to investigate Hg0 adsorption over CuS(001) surface. The results indicated that the chemisorption mechanism was responsible for Hg0 adsorption over CuS(001) surface. The formation of Hg–S and Hg–Cu bonds was confirmed by depicting the projected densities of states profiles. The binding energies of Hg0 suggested that the crystal surface with two sulfur terminations [labeled CuS(001)–S-2] exhibited a better Hg0 adsorption activity than the crystal surface with copper and sulfur terminations [labeled CuS(001)–Cu/S]. Moreover, the adsorption of the flue gas components downstream of WFGD (oxygen, sulfur dioxide, and water vapor) was studied to understand the effect o...

Saline water has been widely used in the flotation of copper sulfide minerals against pyrite where pyrite may be activated by copper ions emanating from copper sulfide minerals. The effect of saline water on copper activation on pyrite surface has not been studied before. In this study, the effect of seawater with a high ionic strength on the flotation of chalcopyrite against pyrite was investigated. Compared to fresh water, seawater significantly increased pyrite recovery in flotation and made the separation of chalcopyrite from pyrite more difficult. The significant increase in pyrite recovery in flotation using seawater mainly resulted from the increased copper activation on pyrite surface. Polarization analysis and EDTA extraction show that the use of seawater enhanced chalcopyrite oxidation and dissolution leading to the formation of a larger amount of copper ions available for copper activation. The flotation of pyrite in the presence of copper ions together with cyclic voltammetry (CV) measurements indicates that the copper activation process on pyrite surface was facilitated in seawater owning to the lower potential of seawater.

Copper is predominantly recovered from sulfide ores by pyrometallurgy – an energy intensive process requiring capture and treatment of released SO2. Whilst some copper ores are amenable to hydrometallurgy, chalcopyrite, the main copper mineral, is challenging to process in aqueous solutions due to surface passivation. The chalcopyrite surface may be less prone to passivation in non-aqueous solvents such as Ionic Liquids. Here we provide the first demonstration that electrochemistry in Deep Eutectic Solvents can solubilise and directly recover high purity copper from solution from three copper sulfide minerals: covellite (CuS), chalcocite (Cu2S) and chalcopyrite (CuFeS2). Cyclic voltammetry supported by EXAFS identifies the metal speciation in solution. In a choline chloride-ethylene glycol DES the main copper species present after dissolution of chalcocite and covellite was [CuCl4]2−. In the solution formed from chalcopyrite, a mix of CuII and CuI species were formed instead. In a choline chloride-urea DES, copper had a mixed chloride/O- or N-donor coordination, potentially altering electrochemical behaviour. Sulfide in the mineral is oxidised to sulfate without the generation of SO2 or H2S. The best selective recovery of copper (99 at%) from chalcopyrite was obtained with a mixed DES of 20 wt% choline chloride-oxalic acid and 80 wt% choline chloride-ethylene glycol. This demonstrates how design of the Deep Eutectic Solvents can enable increased selectivity of copper over iron in the electrowinning stage by changing solute speciation and redox properties.

Typical chemical precipitation methods using lime (Ca(OH)2), soda ash (Na2CO3) and sodium sulfide (Na2S) for removals of heavy metals (i.e. Zn (II), Cu (II) and Pb (II)) from aqueous solutions were compared by jar tests. A focus was especially given to particle size differences and chemical phase conversion of precipitates. A removal of 99.99% from aqueous solutions with three precipitants was achieved for copper and zinc at an initial concentration of 100 mg/L. And lead was efficiently removed (99.75%) by sodium sulfide. In contrast, the maximal lead removals with lime or soda ash precipitation were only 76.14% and 97.78%. The mean particle size of precipitates was in the range of 55 nm–45 μm, depending on properties of precipitants and heavy metal to precipitant ratios. The settling performance of the sludge derived from precipitation was dominated by particle size and Zeta-potential of precipitates. It was observed that ultra-fine copper sulfide particles resulted from the precipitation were around 55 nm and did not settle in 12 h due to electrostatic repulsion force between particles. The main compounds in the sludge obtained from precipitation were metal hydroxides and metal sulfides. However, spontaneous dehydration of metal hydroxide, oxidation of sulfide and atmospheric carbonation were identified by means of XRD and thermal analyses, which is invaluable to the disposal and utilization of the sludge.

Metal sulfides, which are important indicators of sulfur cycling, are usually divided into two categories according to sulfur chemical valence: (1) monosulfides (S2-) and (2) disulfides (S22-). The two sulfur species are separated and quantified by a sequential-extraction method. Specifically, monosulfides are extracted as acid-volatile sulfide (AVS) using 6 M HCl prior to the extraction of disulfides using acidic CrCl2, which is defined as chromium-reducible sulfur (CRS). However, the conventional AVS procedure does not result in the quantitative extraction of S2- from the acid-insoluble metal monosulfide, copper sulfide (CuS). Consequently, residual sulfur in CuS (CuS-S) may be extracted as CRS resulting in the inaccurate separation of these two sulfur species. In this study, we used stannous chloride (SnCl2) to improve CuS-S recovery in the AVS procedure and permit the separate extraction of sulfur from CuS and pyrite (FeS2), the most abundant disulfide in nature. Our results show that the addition of SnCl2 increased the recovery of CuS-S as AVS from less than 36% to as high as 92% in the absence of pyrite and Fe3+ and 89% in the presence of pyrite and Fe3+. In addition, based on the observed correlation between the concentration of SnCl2 and the dissolution of FeS2, we identified the appropriate concentration of SnCl2 needed to avoid the dissolution of FeS2 in the AVS procedure. SnCl2 also minimized the oxidation of CuS-S by Fe3+ released from ferric minerals during the extraction of AVS. Based on the results of a series of sequential-extraction experiments, we show that an amendment of SnCl2 in the AVS procedure followed by CRS permits the quantitative separation of CuS-S and FeS2-S while also preventing interference by Fe3+. Our method will find application in research concerned with the fate of metals and the biogeochemistry of sulfur in the environment.

Copper Sulfide (CuS) thin films were deposited onto a glass substrate using the Chemical Bath Deposition (CBD) technique. The chemical bath Precursors were made up of CuSO4, SC(NH2)2, and C4H6O6. Different parameters have been considered to specify the optimum conditions for fabricating CuS thin films, such as solution temperature, deposition time, pH level, and different precursor concentrations. It has been found that the optimum deposition time is 20 min at temperature 80 &deg, C and pH = 11. The optimum precursor concentrations were 0.15 M, 0.2 M, and 0.1 M of CuSO4, SC(NH2)2, and C4H6O6, respectively. The structural properties of the thin film were studied using X-ray diffraction (XRD), and a single peak was observed for the thin film made at optimum conditions, while all other cases were amorphous. It is obvious from the optical characterization that the transmission spectra show a red-shift for the cases of increasing deposition time, bath temperature, C4H6O6 concentration, and pH. For the case of increasing CuSO4, blue shifts in the transmission spectra were observed. The energy band gap, resistivity, and activation energy of CuS thin films under optimum conditions are 2.35 eV, 0.7 &Omega, &middot, cm, and 0.0152 eV, respectively.

A novel approach for Hydrazine assisted electrolytic hydrogen production using nanocoral structures of cobalt-copper sulfide is portrayed in this work. It is observed that an enormous amount of hydrogen is produced with the present sulfide and is much higherin comparison to copper sulfide and cobalt sulfide alone. The dependency of catalytic activity with respect to sintering temperature and stability of catalyst is also investigated.

Amorphous and crystalline copper sulfide quantum dots (QDs) with good water-solubility were obtained controllably by a novel hydrolysis strategy. These QDs exhibited anti-proliferation activities on cancer cells rather than normal cells and the biological activities are related to their polymorphs. Our study opens up new avenues for fabricating stable water-soluble metal sulfide QDs.

Ligand protected copper nanoclusters with precise compositions have attracted considerable attention due to their unique photoluminescent properties. However, the acquisition of structural information, knowledge of the factors affecting the stability, and high quantum yields are prerequisites for assessing their applications in biomedicine as fluorescent contrast agents, biosensors, and probes for cells. Despite all the effort, only finite examples of single crystal structures of CuNCs are reported. Herein, we report the phosphine-free synthesis and structure determination of 2-PET protected CuNCs. The structure analysis established by single crystal X-ray diffraction reveals the formation of binary Cu74S15(2-PET)45 sulfide cluster. A similar phenomenon has been observed for several other chalcogenide-bridged copper clusters. The synthesized cluster possesses a rod-like structure, protected with 45 thiol ligands on the surface. Fifteen independent bridged-sulfur atoms couple to the copper atoms inside the core. Calculations for both a neutral and negatively charged cluster showed no major differences in their geometrical structures. Further analysis of frontier MO levels of the closed-shell anion predicts the HOMO–LUMO transition to be intramolecular L7 → L1 charge transfer, where “L7” and “L1” abbreviations refer to the corresponding sulfur layer in the structure. For the neutral cluster, the calculated spin density is delocalized over the two moieties. On the basis of TDDFT+TB calculations, the onset of the measured absorption spectrum could be satisfactorily reproduced.

Several studies have been conducted on the benefits of bacteria to replace chemical reagents in the bioflotation process of copper sulfide minerals. Most of the processing of copper sulfide minerals is carried out by flotation by adding reagents. Flotation is one of the mineral processing processes to separate valuable minerals and their impurities by utilizing different mineral surface properties. In copper sulfide minerals there is a high sulfur content of pyrite impurities (FeS2) which must be separated or depressed (become more hydrophilic) to be separated with valuable minerals, while valuable minerals will remain hydrophobic (water-repellent). However, not all bacteria can survive at high sulfur concentrations. In this research, the interaction of biosurfactant-producing bacteria that can survive in environments with high sulfur content (Citrobacter sp. strain SKC-4) with pyrite minerals was characterized. The bacteria-pyrite interaction was observed by analyzing the elemental composition of mineral surface and the morphological changes of the sample with SEM-EDS (scanning electron microscope - energy dispersive spectroscopy). SEM observation showed the interaction of bacteria with pyrite minerals where the bacteria were able to stick and make mineral particles into complex aggregates. Moreover, the EDS results revealed that the presence of bacteria resulted in the change in the elemental composition of the pyrite mineral, which was dominated by iron (Fe), sulfur (S) and a small amount of carbon (C) which was the main element for microbial activity. Sampling for functional group testing (FT-IR Spectroscopy) was carried out on days 0,7,14, and 30 when bacteria interacted with minerals, showing a peak of C=O carbonyl bonds and carboxylic acid formation on the 7th day. The contact angle value of the pyrite decreased after 7 days of interaction with the bacteria, thus resulting in more hydrophilic pyrite minerals. From the results of the interaction characterization, the bacterium Citrobacter sp. strain SKC-4 has the potential as an alternative to a depressant reagent for a more environmentally friendly copper sulfide mineral bioflotation process.

Ethyl isobutyl xanthogenic acetate (EIBXAC) was used as a novel collector in the flotation of secondary copper sulfide minerals owing to its ability to separate copper and sulfur. The collectivity and selectivity mechanisms of this novel collector were investigated using single-mineral and artificial mixed-mineral tests, combined with adsorption tests, fourier transform infrared spectroscopy (FTIR) tests, and density functional theory (DFT) calculations. The results of the flotation indicated that EIBXAC had a better collecting effect than ammonium dibutyl dithiophosphate (ADD) on covellite and digenite, which had an insignificant effect on pyrite. The artificial mixed-mineral experiment indicated that EIBXAC could improve the grade of the copper concentrate while maintaining the same recovery, it had higher efficiency and selectivity. Based on the results of the adsorption and FTIR tests, the adsorption capacities of EIBXAC on the surfaces of covellite, digenite, and pyrite were quite different: Cu-S bonds were formed on covellite and digenite, and Fe-O bonds were formed on pyrite, which was also verified that EIBXAC was chemically adsorbed on the mineral surface. DFT calculations indicated that the adsorption capacity of EIBXAC for covellite and digenite was stronger than that of ADD, which had a weaker adsorption capacity for pyrite. This study can provide theoretical guidance for the application of EIBXAC.

The present study aims to test the degradation ability of KCC-1/CuS nanocomposite as a new photocatalyst for Humic acid (HA) degradation. The degradation process was accomplished using a photocatalytic reaction under irradiation by UV light A facile method applied for catalyst synthesis in different condition, and it was structurally and morphologically characterized, Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Energy-Dispersive X-ray Spectroscopy (EDX) and Thermo Gravimetric Analysis (TGA) which showed successful synthesis of KCC-1/CuS nanocomposite. The degradation process was examined as a function of pH (3–11), catalyst dose (0.005-0.1 g/L), contact time (0–90 min) and initial HA concentration (2–15 mg/L) under UV radiation. The results demonstrated that maximum degradation of HA was 89.5% in optimized environmental conditions including pH: 3, nanocomposite dosage: 0.1 g/L, contact time: up to 90 min and initial HA concentration: 2 mg/L.

The seawater is purified or pre-treated to obtain the acidic seawater-based media (ASM), which has been gradually utilized in copper hydrometallurgical industries, resulting in desirable copper recovery efficiency. In the chemical/bio leaching of chalcocite, chalcopyrite, and other low-grade copper sulfide minerals, the ASM is proved to have a good catalytic effect and it could potentially intervene the leaching reaction and interface condition. In this regard, to further understand the effects of ASM, this paper critically discussed the pivotal ions (ferric/ferrous ions, cupric/cuprous ions, elemental sulfur, passivation ions, silver catalytic ions, etc.) and its compounds, regeneration behavior in the leaching reaction. The current studies tightly related to the effects of these pivotal ions on the redox potential, reaction activation energy, and leaching kinetics were also comparatively analyzed. The tolerances of microorganisms and reactions to ASM were carefully explored. Relied on the previous studies and reviewing in this paper, it inferred that as an efficient, potential alternative of freshwater, the ASM could provide a good expected possibility to accelerate copper sulfide leaching, especially in areas with scarce water resources.

Adsorption of commercial xanthate derivatives on copper sulfide mineral (covellite, CuS) was studied by kinetics and isotherm adsorption experiments. The adsorption of xanthate derivatives was confirmed by FTIR (Fourier transform infrared spectroscopy) and XPS (X-ray photoelectron spectroscopy) results. Experiments were performed with two different xanthate derivatives, C-4410 (O-pentyl S-2-propenyl ester) and C-4940 (isobutyl xanthogen ethyl formate), on individual doses of 0.05 g of powdered covellite. It was found that the equilibrium times at pH 2, 4, and 6 were different for both xanthate derivatives. The shortest times were achieved at pH 2 and 4. The results suggest that C-4110 can be used as collector in a wide range of pH, while C-4940 is limited to lower pH values. Pseudo first- and pseudo second-order kinetics models were thus applied to the experimental data for pH 2. The information obtained from the kinetics models combined with XPS allowed proposing the adsorption mechanism for the covellite-xanthate derivative pair. The adsorption takes place through a non-covalent interaction for C-4410 and chemisorption process for C-4940. The best-fitting isotherm models for C-4410 and C-4940 adsorption were Redlich–Peterson and Freundlich, respectively, which yield a maximum adsorption capacity of 57.07 mg g−1 for C-4410 and 44.62 mg g−1 for C-4940.

Background and Aims Sulfide‐bound copper (Cu) in wine may act as a potential source of hydrogen sulfide. The aim of this study was to understand how the white wine matrix can influence the filterability of sulfide‐bound Cu. Methods and Results Sulfide‐bound Cu was formed in situ with addition of copper(II) sulfate and sodium sulfide to white wine and model wines. The amount of subsequent Cu passing through membrane filters was measured by flame atomic absorption spectroscopy or inductively coupled plasma with optical emission spectroscopy. Nanoparticle tracking analysis was utilised to measure the size of particles generated after copper(II) and sulfide addition. The majority of the particles were around or below 0.2 μm, and polyethersulfone and nylon membranes remove up to 40–90% of sulfide‐bound Cu from white wine. The regenerated cellulose, Teflon and glass fibre membranes removed minimal sulfide‐bound Cu. Conclusions Membrane filtration removed sulfide‐bound Cu by adsorption rather than by particle size discrimination. Polysaccharides and proteins were the components of white wine that most inhibited adsorption. Significance of the Study The addition of copper(II) to wine with hydrogen sulfide results in products that cannot be removed by filtration on the basis of their particle size but instead may be partly removed by adsorption onto membrane filters to an extent impacted by the wine composition and the filtration medium.

Extraction of metals from their sulfide minerals without emitting SO2 could realize an environment-friendly metallurgical route. Here we demonstrate an electrochemical pathway to reduce solid copper sulfide to copper powder in a 50 wt.% NaOH solution. Unlike oxides, most sulfides are semiconductors or electrical conductors and have less formation energy than that of oxides, resulting in a small polarization during electrolysis and less theoretical dissociation potentials. The use of the strongly alkaline solution suppresses the generation of H2, and the electrolyte could dissolve S2− and then shuttle the S2− between cathode and anode. Moreover, a transparent cell was assembled to directly observe the reduction process of solid copper sulfide. On the anode side, the irreversibility of anodic reactions prevents the parasitic reactions, thereby ensuring a current efficiency over 90%. This electrochemical pathway could be employed for extracting various metals from their sulfides without SO2 emissions. Keywords: Electro-desulfurization, Copper sulfide, Alkaline solution, Copper, Inert anode

Copper derivatives are the most prominent CO2 reduction electrocatalyst. Herein, the metallic copper has been electrochemically treated with some of common ionic salts such as N3¯, HPO2¯, S2¯, F¯, Cl¯, Br¯ and I¯ based on the dissolution of a metallic working electrode in an aqueous solution to derive the surface roughness incorporated with nanostructures. Diverse surface morphology can be obtained when the ionic radii of anions are changed. Surface study reveals various roughness shapes based on the size and polarity of the anions, where the ions with higher ionic radii have higher impact on the Cu surface. In comparison, polyatomic oxyanion such as HPO2¯ even with large ionic radii do not have enough strength to create the surface roughness than that of oxygen-free anions with large ionic radii. The photoelectrochemical behavior of the modified surfaces toward CO2 reduction is studied at a wide potential window in bicarbonate aqueous solution. Based on our investigations, treated surfaces by I¯, Cl¯ and S2¯give a more surface roughness, while I¯ and N3¯ offer higher catalytic activity toward CO2 reduction due to possible complexing ability of these anions with Cu cations, followed by formation of the co-catalyst semiconductor and facilitate electron transfer. This methodology can be applied to investigate the effect of ions on transition metals along with obtaining different surface morphologies tailored to different applications.

Multifunctional nanotheranostic agent with high performance for tumor site-specific generation of singlet oxygen (1O2) as well as imaging-guidance is crucial to laser-mediated photodynamic therapy. Here, we introduced a versatile strategy to design a smart nanoplatform using phase change material (PCM) to encapsulate photosensitizer (zinc phthalocyanine, ZnPc) in copper sulfide loaded Fe-doped tantalum oxide (Fe-mTa2O5@CuS) nanoparticles. When irradiated by 808 nm laser, the PCM is melted due to the hyperthermia effect from CuS nanoparticles, inducing the release of ZnPc to produce toxic 1O2 triggered by 650 nm light with very low power density (5 mW/cm2). Then, the produced heat and toxic 1O2 can kill tumor cells in vitro and in vivo effectively. Furthermore, the special properties of Fe-mTa2O5 endow the nanoplatform with excellent computed tomography (CT) and T1-weighted magnetic resonance imaging (T1-MRI) performance for guiding and real-time monitoring of therapeutic effect. This work presents a feasi...

Ethanediamine was used to modify the mineral surface of malachite to improve its sulfidization and flotation behavior. The activation mechanism was investigated by adsorption experiments, X-ray photoelectron spectroscopy (XPS) analysis, and zeta potential measurements. Microflotation experiments showed that the flotation recovery of malachite was enhanced after the pretreatment of the mineral particles with ethanediamine prior to the addition of Na2S. Adsorption tests revealed that numerous sulfide ion species in the pulp solution were transferred onto the mineral surface through the formation of more copper sulfide species. This finding was confirmed by the results of the XPS measurements. Ethanediamine modification not only increased the contents of copper sulfide species on the malachite surface but also enhanced the reactivity of the sulfidization products. During sulfidization, Cu(II) species on the mineral surface were reduced into Cu(I) species, and the percentages of S22− and Sn2− relative to the total S increased after modification, resulting in increased surface hydrophobicity. The results of zeta potential measurements showed that the ethanediamine-modified mineral surface adsorbed with more sulfide ion species was advantageous to the attachment of xanthate species, thereby improving malachite floatability. The proposed ethanediamine modification followed by sulfidization xanthate flotation exhibits potential for industrial application.

Inkjet-printing of metal nanoparticles is a particularly promising technique for the fabrication and modification of surfaces with a multifunctional nature. Recently copper sulfide nanoparticles (CuS NPs) have attracted wide interest due to a range of valuable properties including long term stability, photo-thermal activity, ease of synthesis and low cost. In the present study, printed CuS patterns were successfully fabricated on latex coated paper substrates and characterized by means of atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), UV–Vis-NIR spectroscopy, and grazing incidence X-ray diffraction (GID). The resulted patterns displayed pronounced photo-thermal effect under Near Infrared Irradiation (NIR) even with relatively low laser power. Finally, by utilizing an automated real-time imaging platform it was possible to verify that the CuS printed film was not cytotoxic to human dermal fibroblast cells (HDF). The pronounced photo-thermal properties and nontoxic nature of these printed low-cost flexible CuS films make them promising candidates for fabrication of devices with localized photo-thermal effect suitable for biomedical applications.

Constructing a novel enzyme-free electrode for sensitive and selective detection of hydrazine (N 2 H 4 ) in neutral medium is important. In this paper, Copper sulfide (CuS) with different morphologies were synthesized for electrochemical sensing of N 2 H 4 . A facile hydrothermal approach is developed for the shape-controlled synthesis of CuS architectures. The effects of reaction temperature, time, solvent and anion type on the morphologies of CuS were studied and it was found that CuS with flower-like, nanoparticle-like, rod-like and multilayered-like morphologies could be selectively prepared by just changing the type of metal precursor. The electrochemical performances of various CuS structures were investigated, which showed that flower-like CuS exhibited higher electrocatalytic activity toward N 2 H 4 oxidation and could offer superior analytical performances with a wide linear range of 0.5 μM to 4.775 mM, a high sensitivity of 359.3 μA mM −1 cm −2 and a low detection limit of 0.097 μM (S/N = 3). Moreover, the application of the sensor for detecting N 2 H 4 in tap water samples was demonstrated and the good recovery obtained made it a great potential for practical use.

Copper specimens were exposed to Sulfate-Reducing Bacteria (SRB) for 10 months under the conditions corresponding to the final disposal of high-level nuclear waste. In-situ electrochemical impedance spectroscopy (EIS) measurements were carried out to characterize the surface-environment interface after various times of exposure. The EIS results are interpreted in terms of the Point Defect Model (PDM), in order to obtain kinetic information on the formation of the Cu2S passive film. The standard rate constant and the rate constants for the surface reactions revealed that the Cu2S layer is a p-type semiconductor. The diffusion constant for cation vacancies in the barrier layer and the average bulk cation vacancy concentration in the barrier layer were found to be on the orders of 10−13 cm2·s−1 and 1022 cm−3, respectively, i.e., both slightly higher than reported in literature for corresponding electrochemically developed Cu2S layers. The electric field strength was approximately 3·105 Vcm−1 at all measurement points. These results are presented and discussed in this work in the light of storage of high-level nuclear waste.