Copper Hydroxysulfate Research Articles

Uncharacteristic Adsorption Breakthrough Behavior of a Core–Shell Copper Hydroxysulfate Metal–Organic Framework Against Gaseous Formaldehyde

AbstractCore–Shell structured microspheres with a packed nano‐platelet copper hydroxysulfate (CHS) core and an octahedral crystalized metal–organic framework‐199 (CHS@M199) shell are synthesized and tested as adsorbent for gaseous formaldehyde (FA). CHS@M199 outperforms reference materials (e.g., activated carbon (AC), CHS, and M199) with adsorption capacity (Q) of 8.13 mg g−1 and partition coefficient (PC) of 0.263 mol kg−1 Pa−1 against 10 Pa FA at 10% breakthrough (BT) level with the aid of large surface area and copper sites for coordinating with carbonyl group. Contrary to general expectations, CHS@M199 exhibits a unique adsorption behavior in that BT volume increases systematically with the rise in FA inlet partial pressure (e.g., 5–10 Pa). The 10% BT capacity of CHS@M199 decreases noticeably (8.13 to 2.08 mg g−1) with increasing relative humidity (0.016 to 10%), reflecting water‐FA competition for hydrophilic adsorption sites. Although FA adsorption on CHS@M199 diminishes with elevated RH levels, such reduction intensifies when simulating ambient conditions (through stepwise addition of competing components: O2, CO2, and H2O). The FA adsorption on CHS@M199 is well described by both pseudo‐first‐order (PFO) and pseudo‐second‐order (PSO) kinetics. Polymerization may play a pivotal role in the adsorption of FA on CHS@M199, as Qi‐LeVan isotherm best fits the experimental data.

The accelerated recovery of silver using the nitrite-copper novel system: Development of the kinetic model

This research presents a systematic-kinetic analysis of silver leaching from pure metallic silver using the NO2-Cu2+ novel system, with the aim to maximize the silver recovery and decrease the massive consumption of reagents. The effect of pH, nitrite ions concentration, cupric ions concentration, temperature and stirring rate on silver leaching kinetics and recovery was evaluated. The thermodynamic and leaching results showed that a decrease of pH from 5.4 to 4.5 increases remarkably the silver leaching kinetics, while the parasite precipitation of copper hydroxysulfate species is inhibited. The silver leaching kinetics is also favored when nitrite and copper concentrations are increased up to 1.5 and 0.2 M, respectively. The fundamental kinetic analysis revealed that silver leaching mechanism from its metallic form with this system was incomplete and follows the next kinetic model: t = [ 10-0.52pH [NO2–]1.2 [Cu2+]0.522.63 × 109e-56,900/RT][ 1–3(1-x)2/3 + 2(1-x)], where the diffusion of fluid species through a non-conventional ash layer is the rate determining step of the leaching process. Finally, the dissolved silver can be easily recovered in its metallic form (high purity > 99%) using a simple cementation step, which permits the recycling of the leaching solution.

Adsorption behavior and mechanism of Hg (II) on a porous core-shell copper hydroxy sulfate@MOF composite

Herein, a porous core-shell copper hydroxy sulfate@metal-organic framework decorated by 2,5-dimercapto-1,3,4-thiadiazol (DMTZ) was synthesized via a facile self-template strategy for the capture of Hg2+. The strategy of assembling MOF shell on copper hydroxy sulfate (CHS) core avoided the self-nucleation of MOF(Cu3(BTC)2) in the solution and complex multistep procedures by means of in situ transformation the metal source CHS into well-defined Cu3(BTC)2 crystal. The structure and properties of the DMTZ modified CHS@Cu3(BTC)2 (CHS@Cu3(BTC)2-DMTZ) was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA) and N2 sorption–desorption isotherms (BET). The adsorption behavior followed Langmuir adsorption model and the maximum adsorption capacities for the removal of Hg2+ was up to 627.6 mg g−1. 99.96% Hg2+ was rapidly captured by CHS@Cu3(BTC)2-DMTZ within 10 min from 40 mg L-1 to 0.014 mg L-1. Meanwhile, not only X-ray photoelectron spectroscopy (XPS) but also Raman spectra verified the selective and strong interaction between Hg2+ and thiol/nitrogen-containing functional groups of DMTZ on CHS@Cu3(BTC)2-DMTZ. These results manifested that this novel thiol-functionalized MOF adsorbent had superior adsorption capacity and selective for Hg2+.

Geochemical Appraisal of Mine Discharge and Tailing at Malanjkhand Copper Mine, India

Abstract The Malanjkhand copper deposit, which is the largest open cast copper mine in Asia, is located in central India. The detailed hydrogeochemical study indicates that mine discharges are mostly highly acidic (pH 3.4–6.1) with very high concentration of Cu (9.2–60.8 mg/L). Water releases from the tailing pond is also acidic in nature (pH 2.39–2.48) and contains high concentration of Cu (15.6–65.2 mg/L). The water quality of the mine discharges and tailing is mainly affected by the oxidation of chalcopyrite, which presents abundantly in the host rock along with minor amount of pyrite. The blue coloured secondary mineral that precipitates along the course of the mine effluents is dominated by amorphous copper hydroxysulfate. Alpersite, gypsum, epsomite and hexahydrite occur as efflorescent salts during the summer time, and store very high concentration of metals. Alpersite contains Zn (285-391 mg/kg), Ni (62-78 mg/kg) and Cu (7.8-10.9%) whereas epsomite contains Zn (132-160 mg/kg), Ni (35-43 mg/kg) and Cu (3465-4184 mg/kg). Among the trace elements in tailing, Cu has the highest concentration ranges (98.2–4492 mg/kg) followed by Mn (131.4–760 mg/kg), Zn (54.3–241 mg/kg), Ni (25.7–170.3 mg/kg), Pb (12.5–46.4 mg/kg) and Cd (0.72–1.48 mg/kg). Tailing rich with efflorescent salt has maximum concentration of metals as well as maximum potential for releasing metals into the aqueous system.

Highly active, stable and self-antimicrobial enzyme catalysts prepared by biomimetic mineralization of copper hydroxysulfate.

A nature-inspired approach to encapsulate enzymes in spindle-like copper hydroxysulfate nanocrystals was developed by a biomimetic mineralization process. Several types of enzymes including glucose oxidase (GOx), horseradish peroxidase (HRP), Candida antarctica lipase B (CALB) and cytochrome c (Cyt c) were successfully encapsulated in copper hydroxysulfate nanocrystals quickly (within 1 hour) with maintained or even greatly enhanced catalytic efficiencies (kcat/KM of Cyt c showed a 143-fold increase) and high stabilities, demonstrating the feasibility of utilizing copper hydroxysulfate nanocrystals as a novel type of nanocarrier for enzyme immobilization. In addition, by this approach, for the first time, we showed that an immobilized enzyme can be endowed with self-antibacterial activity by an inorganic component. This self-antibacterial performance together with the improved catalytic efficiencies and stabilities can greatly benefit the enzymatic catalysis in aqueous media and promote the future development of novel biosensors.

Silver leaching with the thiosulfate–nitrite–sulfite–copper alternative system

In the recent years, several silver leaching technologies have been investigated in order to find out an alternative and sustainable leaching process; one of these alternatives is the thiosulfate. The main research line is focused in the use of thiosulfate with copper as a catalyst and ammonia as a cupric ion stabilizer; however, the ammonia is also another toxic reagent. For that reason, an alternative-new leaching system using thiosulfate–nitrite and copper ions was investigated in this work. This new leaching system is able to dissolve silver without the use of cyanide or ammonia due to the cupric–ammonia complexes in-situ production, which is possible through the reaction of the nitrite and the cupric ions at neutral pH and NO2:Cu molar ratio of 30:1, according to silver leaching experiments and thermodynamic predictions.On the other hand, the effect of sulfite concentration was studied in the leaching solution revealing that the reductive ability of the sulfite ions has a negative effect on the silver leaching kinetics and recovery. It was also found that an increase in the pH of the leaching solution from 7 to 9.6 promotes the precipitation of copper hydroxide species which inhibits the silver leaching kinetics.Finally, copper–ammonia complex formation was also confirmed in the silver leaching by the UV–Visible spectroscopy technique. The solid leaching residues obtained at neutral pH were analyzed by X-ray diffraction and scanning electron microscopy showing the formation of a copper hydroxysulfate species called antlerite; this result was also confirmed by species distribution diagrams.

A fast synthesis of hierarchical yolk–shell copper hydroxysulfates at room temperature with adjustable sizes

Hierarchical 3D yolk–shell copper hydroxysulfate microspheres were successfully synthesized by a fast synthesis method at room temperature. Both the core and the shell of the yolk–shell microspheres were assembled from 2D nanoplates or tiny nanoplatelets. The as-synthesized products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectrometry (XPS), atomic absorption spectrophotometry (AAS) and thermogravimetric analysis (TG). The diameter of the yolk–shell microspheres can be tuned by simply adjusting the concentration of the chelating agent, 1,3-propanediamine. This reaction can be scaled up by a factor of 1000 with almost no loss in yield. An Ostwald ripening controlled formation mechanism was proposed. Furthermore, the yolk–shell copper hydroxysulfates were evaluated as catalysts for the oxidation of styrene to benzaldehyde.

Electrochemical Properties of Nanostructured Copper Hydroxysulfate Mineral Brochantite upon Reaction with Lithium

Cu-containing conversion electrodes have received much study as high capacity electrodes for lithium-ion batteries, but many suffer from poor reversibility. The electrochemical properties of the copper hydroxysulfate compound, Cu4(OH)6SO4, more commonly known as the mineral brochantite and as a patina constituent on the Statue of Liberty, were investigated. Nanostructured brochantite was synthesized using precipitation and microwave-assisted hydrothermal reactions and evaluated in half-cells with Li metal counter electrodes. Reversible capacities >400 mAh/g corresponding to the 2 electron reduction of Cu(2+) and discharge potential of 1.8 V versus Li/Li(+) were observed in brochantite with a nanoplate morphology. Detailed characterization using X-ray diffraction, scanning and transmission electron microscopy, and X-ray photoelectron spectroscopy was performed to better understand the conversion process.

Spectroscopic characterization of an innovative biological treatment for corroded metal artefacts

Nowadays, organic coatings such as waxes, acrylic resins, and corrosion inhibitors are commonly used for the protection and corrosion inhibition of metal artefacts. However, research efforts still need to be emphasized on innovative treatments that aim at modifying existing corrosion products into more stable and less soluble compounds while maintaining the surface's appearance. Within the framework of the Biological patinA for arcHaeological and Artistic Metal ArtefactS project, biological treatments based on such criteria are being evaluated for the preservation of metal artefacts. In particular, the capacity of a fungal strain, Beauveria bassiana, to precipitate copper oxalates is exploited for the stabilization of soluble patinas (copper hydroxysulfates) or the transformation of active corrosion products (copper hydroxychlorides). In fact, copper oxalates produce green compact patinas showing a high degree of insolubility and chemical stability even in acid atmospheres (pH 3). In the present work, cultures of B. bassiana were applied on copper‐based coupons naturally aged in urban or marine environment. The results clearly showed that the original patina was gradually transformed into copper oxalates and that the conversion is completed on the surface areas where B. bassiana grew. Cross‐sectioned samples were also analyzed to determine the distribution of the copper oxalates. Raman mapping was demonstrated here to be a valuable tool for precisely and nondestructively localizing corrosion products and for evaluating protective treatments on metal artefacts. This study also permitted the further improvement of the treatment to be easily and directly applied in situ by conservators–restorers. Copyright © 2012 John Wiley & Sons, Ltd.

Electrochemical Fabrication of Copper-Based Hybrid Microstructures and Mechanism of Formation of Related Hierarchical Structures on Polypyrrole Films

The surface electrochemistry of polypyrrole–polystyrene sulfonate (PPy–PSS) thin films is exploited for the fabrication of novel hybrid copper-based microstructures. The electrochemical deposition of the copper-based materials at the PPy–PSS film is strongly dependent on the electrode potential. This dependence is studied at three different potentials: 0.10, 0.00, and −0.10 V vs SCE. Hierarchical micro/nanostructures made of copper hydroxysulfate salts are only formed at 0.10 V vs SCE and are replaced with branched and single microcrystals of Cu2O covered by a thin layer of Cu(OH)2 at 0.00 and −0.10 V vs SCE, respectively. The different structures can be coupled on the same film through a simple fabrication procedure to give hybrid microstructures. These novel hybrids consist of a central microcrystal (deposited at −0.10 V vs SCE) and a surrounding contour of welded nanosheets (deposited at 0.10 V vs SCE). The mechanism of nucleation and growth of the hierarchical micro/nanostructures formed at 0.10 V vs SCE is also reported. These structures are made from the assembly of nanoparticles into nanowires, nanosheets, and microclusters. These microclusters have a flowerlike shape within which each nanosheet forms a petal of the flower. The nucleation of the clusters is shown to be progressive.

Sonochemical shape control of copper hydroxysulfates

Shape control of inorganic nanoparticles generally requires the use of surfactants or ligands to passivate certain crystallographic planes. Additive free shape control methods utilize the differences in the growth rates of crystallographic planes. We combined this approach with the sonochemical method to synthesize copper hydroxysulfate (Brochantite) with morphologies ranging from flowers, to bricks, belts and needles. Sodium peroxydisulfate, which was used as the sulfate and hydroxide source, was decomposed thermally and/or sonically under various pH and temperature conditions. The relative release rates of the sulfate and hydroxide anions determined the final form of the crystals. This technique yielded products even at acidic pH, marking a distinction from the literature reactions, which start with stoichiometric amounts of sulfate and hydroxide anions and yield only a single crystal morphology.

Electrochemical Deposition of Hierarchical Micro/Nanostructures of Copper Hydroxysulfates on Polypyrrole−Polystyrene Sulfonate Films

Copper-based hierarchical micro/nanostructures were prepared using a novel electrochemical route on polypyrrole−polystyrene sulfonate (PPy−PSS) thin films. The resulting structures are composed of copper hydroxysulfates, as confirmed by the electrochemical, spectroscopic, and X-ray diffraction characterization. The electrochemistry of the film is a key factor in the overall deposition of the micro/nanostructures. The PPy−PSS films capture cations from the copper sulfate electrolyte solution and facilitate the reduction of dissolved oxygen to hydroxide ions. The system then acts like a nanoreactor as the Cu2+ and OH− ions are concentrated on the polymer surface, which in the presence of the SO42− ions from the electrolyte solution results in the electrocrystallization of the copper hydroxysulfates hierarchical structures.

Synthesis, structure and magnetic properties of copper hydroxysulfates

Cu 3(OH) 4SO 4 and Cu 4(OH) 6SO 4, synthetic equivalent of antlerite and brochantite minerals, have been obtained by hydrothermal synthesis from copper sulfate, soda and H 2O or D 2O. Their structures have been refined from single crystal X-ray and/or powder neutron diffraction data. They consists of edge-shared copper octahedron infinite chains connected to each other to define either triple chains in the case of antlerite or corrugated planes in the case of brochantite. Sulfate groups connect the former copper entities. From magnetic susceptibility measurements, both samples reveal a transition towards a 3D antiferromagnetic long range order at low temperature. In the paramagnetic domain, AF interactions are predominant for brochantite whereas ferromagnetic ones are evidenced for antlerite. The magnetic structures have been determined from powder neutron diffraction data and reveal the presence of ferromagnetic chains AF coupled. The magnetic results have been related to the Cu-O-Cu bridge angle values.

Comportement thermique des seleniates de cuivre, CuSeO 4 · 5 H 2O et CuSeO 4 · 2 Cu(OH) 2

Although the thermal decomposition of copper hydroxysulfates and sulfates is well known to afford the dolerophanite CuSo 4 · CuO (a stable phase), the present study indicates that, upon heating, copper hydroxyselenate and selenate CuSeO 4 · 2 Cu(OH) 2 and CuSeO 4 · 5 H 2O lead to the oxoselenite CuSeO 3 · CuO. However, it seems that the presence of oxyselenate CuSeO 4 · CuO can only be evidenced in a restricted temperature range depending on the degree of crystallinity of the related hydroxyselenate compound.