Electrochemical investigations of copper etching by Cu(NH3)4Cl2 in ammoniacal solutions

Cyclic voltammetry has been employed to investigate the mechanism of copper etching in ammoniacal buffered solutions of cupric chloride. Experiments involving an increase in the solution copper content (up to 0.5 m) and in the thickness of the copper electrode have been used to obtain a better understanding of the copper oxidation. Whatever the Cu(ii) concentration, the reduction occurred in two one-electron stages leading successively to Cu(i) and Cu(0). The concentration of ammonia was an important parameter. Increasing the ratio of Cu : NH3 favoured the formation of transient solid compounds. The expected two-step oxidation of copper was observed only for thin layers of electroplated copper. The determination of the corrosion current in etching solutions suggests that copper oxidation involves the formation of solid cuprous compounds.     

Soluble Copper Xanthate Complexes

Abstract

When solutions of cupric perchlorate (10^?6 to 10^?2 M) are mixed with solutions containing nonequivalent quantities (concentrations) of xanthate (O-alkyl-dithiocarbonate) ions, clear solutions containing soluble nonionic and ionic complexes are obtained, despite the fact that the solubility product for a given metal xanthate salt may be exceeded by several orders of magnitude. Ultraviolet and visible (UV and VIS) spectroscopy, and dc and ac differential polarography have been employed to study these complex species.

The spectral changes taking place on the addition of potassium ethyl xanthate to cupric perchlorate solutions, and also turbidity measurements, indicate that copper xanthate complexes are formed before the precipitation of cuprous ethyl xanthate, Cu(S₂ COC ₂ H ₅). In very dilute solutions containing near equivalent concentrations of the reactants, a spectrum containing three broad maxima (235, 285, and 375 nm) is obtained and is interpreted as due to a nonionic cupric complex, Cu(S₂ COC ₂ H ₅)₂, (I). In the presence of excess cupric ions a second complex, an ionized cupric monoxanthate, Cu(S₂COC₂H₅)+, (II), is formed with bands at 256, 283, 325, and 382 nm. The relative concentrations of the reactants determine not only which complex is formed in these dilute solutions, but also whether or not the cuprous xanthate precipitates.

The species in solutions giving the spectrum of complex (I) is not stable. It decomposes quickly to cuprous xanthate and dixanthogen. Solutions of the ionic cupric complex (II) are stable for many for many hours. It is suggested that the ionic complex (II) may play a role in activating sphalerite in alkaline solutions.     

Reaction and nucleation mechanisms of copper electrodeposition from ammoniacal solutions on vitreous carbon

The reaction and nucleation mechanisms of the electrodeposition of copper from ammoniacal solutions were investigated by cyclic voltammetric (cv) and chronoamperometric (ca) techniques, respectively. Each experiment with both electrochemical techniques was followed by morphological studies by atomic force microscopy (AFM). With respect to pH, the studies were performed on ammoniacal solutions at pH 4, pH 6, and pH 8, each representing a characteristic predominance region in E-pH diagrams. The experimental parameters were copper concentration, scanning rate, deposition potential, and electrode conditioning. It was found that at pH 4 copper electrodeposition occurs via reduction of cupric species to cuprous, which in turn can be either reduced, or disproportionated to metallic copper. At pH 6, deposition occurs from free and complexed cupric species, while at pH 8, only cupric amine complexes are involved. Copper nucleates according to instantaneous mechanisms at pH 4, and progressive nucleation mechanisms at pH 6 and pH 8. The diffusion coefficients of the copper species involved were also determined and are reported in this study.     

Sorption of Gold(I) from Ammoniacal Solutions into ∝‐Zirconium(IV) Bismonohydrogenphosphate (∝‐Zrp) Intercalated with Butylamine

Studies on sorption of diammine Au(I) cationic complex from ammoniacal solutions of varying composition into pure and modified with butylamine α‐ZrP have been performed in the temperature change from 40 to 80°C. Experimental results have been discussed in terms of first order reaction kinetics. The activation energies of sorption of Au(I) into pure and modified α‐ZrP were found to be equal to 28 (± 3) and 84 (± 7) kJ?mol^?1, respectively. The effects of concentrations of ammonia, ammonium sulfate and Cu(II) were also examined. The kinetic parameters of sorption of tetraammine Cu(II) complex from ammoniacal solutions into modified α‐ZrP were also determined.     

Hydrometallurgical process for the recycling of copper using anodic oxidation of cuprous ammine complexes and flow-through electrolysis

Flow-through electrolysis for copper electrowinning from cuprous ammine complex was studied in order to develop a hydrometallurgical copper recycling process using an ammoniacal chloride solution, focusing on the anodic oxidation of cuprous to cupric ammine complexes. The current efficiency of this anodic oxidation was 96% at a current density of 200 A m⁻² under a batch condition. In a flow-through electrolysis using a sub-liter cell and a carbon felt anode, the anodic current efficiency increased with the flow rate and was typically higher than 97%. This tendency was explained by the backward flow of the cupric ammine complex, which was formed on the anode, through the diaphragm. The anodic overpotential was lower than 0.3 V even at an apparent current density of 1500 A m⁻². A similar current efficiency and overpotential were also achieved in a liter scale cell, which indicates the scale flexibility of this electrolysis. The power consumption requirements for copper electrowinning in this cell were 460 and 770 kWh t⁻¹ at the current densities of 250 and 500 A m⁻², respectively, which were much lower than that of the conventional copper electrowinning despite the longer interpolar distance.     

Anodic oxidation of copper cyanide on graphite anodes in alkaline solution

The anodic oxidation of copper cyanide has been studied using a graphite rotating disc with reference to cyanide concentration (0.05–4.00 M), CN:Cu mole ratio (3–12), temperature (25–60 °C) and hydroxide concentration (0.01–0.25 M). Copper had a significant catalytic effect on cyanide oxidation. In the low polarization region (about 0.4 V vs SCE or less), cuprous cyanide is oxidized to cupric cyanide complexes which further react to form cyanate. At a CN:Cu ratio of 3 and [OH^–] = 0.25 M, the Tafel slope was about 0.12 V decade^–1. Cu(CN)₃ ^2– was discharged on the electrode and the reaction order with respect to the predicted concentration of Cu(CN)₃ ^2– is one. With increasing CN:Cu mole ratio and decreasing pH, the dominant discharged species shifted to Cu(CN)₄ ^3–. Under these conditions, two Tafel slopes were observed with the first one being 0.060 V decade^–1 and the second one 0.17–0.20 V decade^–1. In the high polarization region (about 0.4 V vs SCE or more), cuprous cyanide complexes were oxidized to copper oxide and cyanate. Possible reaction mechanism was discussed.     

Production of nanoparticles of copper compounds by anodic dissolution of copper in organic solvents

The anodic behaviour of copper was investigated in ethanol solution containing LiClO₄, LiCl electrolyte and water. The type of electrolyte and the water content influences the mechanism of the anodic process and the formation of anodic products. In LiClO₄ electrolyte the dissolution of copper is related to the oxidation of Cu(I) to Cu(II). In solutions of LiCl the etching of copper begins with the creation of soluble complexes of Cu(I) with chloride ions and solvent molecules. At potentials above 0.4 V the formation of alkoxides was observed in both solutions, characterized by a yellow tint. On the other hand, above 0.8 V (i.e. above the equilibrium potential of alcohol oxidation) copper dissolution is accompanied by the formation of a blue colloidal suspension of Cu (II) copper salt. Anodic etching of copper in solutions containing 3% H₂O at potentials higher than 0.4 V leads to the formation of colloidal suspension of copper oxide nanoparticles.     

明胶生物大分子中铜离子配位状态初探

本文对明胶生物大分子中铜离子的配位状况进行了初步研究。首先用原子吸收光谱法测定五种国产明胶中铜含量,然后用电子顺磁共振波谱法(EPR)研究明胶中铜的配位状况。结果表明,A、B、E三种胶中含铜量少于5ppm,在EPR谱上反映不出Cu(Ⅱ)的存在;C、D两种胶中含铜大于20ppm,在EPR谱上表现出Cu(Ⅱ)的信号,且信号位置相似,说明二者Cu(Ⅱ)的配位环境存在某些类似;以C胶作为主要研究对象,发现C胶中同时存在顺磁性的Cu(Ⅱ)离于和抗磁性的Cu(Ⅱ)离子的配位结构可能偏离平面四方构型,即不存在D_(4h)对称轴;Cu(Ⅱ)离子属于典型的二型铜,有两个或两个以上组氨酸咪唑基以N原子与Cu(Ⅱ)配位。     

An integrated chemicalelectrochemical method for the recovery of copper from dilute solutions

The addition of reducing agents such as hydrazine or sodium sulphite to buffered dilute copper solutions containing chloride ions reduces cupric ions to cuprous ions chemically, thus by-passing this rate-determining electrochemical step. The subsequent electro-deposition of cuprous ions can then proceed readily and the overall faradaic efficiency, based on a 2 electron process, may reach 141%.     

Dissolution of copper scrap in hydrochloric acid

The dissolution of copper scrap has been investigated as a possible approach to the production of copper chloride solutions for certain metallurgical purposes. The principal stages involved in the dissolution have been found to be (1) diffusion-controlled attack of cupric ions on the surface of the copper, and (2) re-oxidation of cuprous ions by oxygen. The effects of chloride concentration, acidity, temperature, agitation, metal surface area and oxygen partial pressure are described.     

Analysis of the Molecular Structure at the PPS/Copper Interphase and its Role in Adhesion

X-ray photoelectron spectroscopy (XPS) was used to examine the interfacial chemistry in polyphenylene sulfide (PPS)/copper bonded laminates. Several surface pretreatments were studied including a simple methanol wash, two acid etches, thermal oxidation and chemical oxidation. Peel test analysis showed poor adhesion to the methanol-washed and acid-etched foils, giving a peel strength of only 3-5 g/mm. XPS analysis of the failure surfaces revealed a large amount of inorganic sulfide at the interface with reduction of the copper oxide. Chemical oxidation using an alkaline potassium persulfate solution gave a matt-black surface consisting of primarily cupric oxide. These samples showed improved adhesion and XPS analysis of the failure surfaces revealed fracture through a mixed PPS/cuprous oxide layer. A simple thermal oxidation yielded a cuprous oxide surface layer and laminates bonded to these surfaces showed a more than ten-fold increase in peel strength. XPS analysis of the failure surfaces showed much lower amounts of interfacial copper sulfide and it was postulated that excess sulfide at the interface was responsible for the poor adhesion observed for other pretreatments.     

Electrochemical behaviour of copper in aqueous solution containing potassium ethylxanthate

The electrochemical behaviour of copper in aqueous potassium ethylxanthate (KEX) is studied by using potentiodynamic techniques at different sweep rates, complemented with SEM and EDAX. In NaCl solutions a cuprous xanthate film is formed at low potentials, the initial stage of this reaction being the electroadsorption of KEX on copper competing with the adsorption of chloride ions and water. At low surface coverages for electroadsorbed KEX the electrodissolution of copper is partially inhibited as compared to plain NaCl solutions. As the KEX monolayer is completed, a tri-dimensional cuprous xanthate film grows in the electrode surface. On subsequent increase of the applied potential a complex anodic layer is formed leading to copper passivity. Passivity breakdown promoted by either chloride ions or electro-oxidation of the organic film can be observed when the potential exceeds a certain critical value.Facultad de Ciencias Exactas, Universidad Nacional de La Plata.     

电磁屏蔽导电涂料用镀银铜粉的制备

采用置换反应法制备镀银铜粉时,铜粉还原银氨溶液中的Ag+生成的Cu2+与NH3形成络合物[Cu(NH3)4]2+,它吸附于铜粉表面而阻碍还原反应的继续进行,使制备的镀银铜粉表层的银含量降低。用氨水提高银氨溶液的pH,可增加制备的镀银铜粉表层的银含量,提高其抗氧化性能。当用氨水调节银氨溶液的pH至11.50时,可制得表层银的质量分数高达47.91%且具有常温抗氧化性能的镀银铜粉。研究了pH、AgNO3用量、AgNO3浓度和反应温度对镀银铜粉的抗氧化性能的影响。     

Cementation-induced recovery of self-assembled ultrafine copper powders from spent etching solutions of printed circuit boards

Ultrafine copper powders have been recovered from spent etching solutions of printed circuit boards by cementation on helical-form iron scrap chips. The tested solution is an ammoniacal copper solution containing 135 g/l copper with minor impurities. The influences of contact time, temperature, pH, initial copper concentration and Fe stoichiometry on the yield, purity and grain size and shape of the precipitated copper powders were studied. Ultrafine self-assembled copper nanocubes with high purity of about > 99% was obtained at temperature 25 °C, time 20 min, pH 2, Fe stoichiometry 1X and initial copper concentration 20 g/l Cu. It was proposed that the precipitation of copper from the solution involved two main processes: (1) adsorption of copper ions on the surface of the iron chips due to the iron oxides present on it and (2) cementation of copper ions onto the metallic iron contained in the chips. Scrap iron chips is seen to be an effective material for copper powder recovery from spent etching solutions in a pure and fine form.     

Room-Temperature Electrochemical Assembly of Copper/Cuprous Oxide Nanocomposites

Nanocomposite films of copper metal and cuprous oxide, Cu₂O, are electrodeposited at room temperature from alkaline solutions of copper(II) lactate. The electrode potential oscillates spontaneously if the films are deposited galvanostatically. The oscillation period is a function of pH, varying from 69 seconds at pH 8.7 to 11 seconds at pH 9.7. No oscillations are observed if the pH is below 8.5 or above 10. The phase composition of films deposited at 0.5 mA/cm² is a function of pH. The composition varies from nearly pure copper (93 mole%) at pH 8, to 42 mole% copper at pH 9.5, to pure cuprous oxide when the pH exceeds 10. The observation of quasi-periodic potential oscillations suggests that the nanocomposites are layered. The calculated faradaic thickness of cuprous oxide is 5–8 nm, and the thickness of the copper layer is 1–11 nm. The thickness of each of the layers increases as the pH is lowered.     

Advances and future prospects in copper electrowinning

In recent years research on the electrowinning of copper has led to a number of significant advances. These developments include improved mass transfer and higher current density operation through air sparging, reduced anode overvoltage in the conventional cell as a result of cobalt(II) addition to the electrolyte or the use of alternative types of anodes, and the production of high quality cathodes in the electrowinning of copper from solvent extraction strip liquor. The fluidized-bed cathode offers the possibility of continuous electrowinning as well as the direct electrowinning of copper from dilute solutions. The problem of high power consumption may find its solution in the adoption of an alternate anode reaction or in the electrowinning of copper (I) electrolytes. Noteworthy is the development of unique electrowinning cells in conjunction with the hydrometallurgical treatment of copper concentrates. These cells utilize cuprous or ferrous anodic oxidation with the resulting cupric or ferric ions being active lixiviants of sulphide copper minerals. The numerous advances combined with the increasing tonnage of copper being produced by the electrowinning route ensure an interesting and promising future for this process.     

铜粉处理酸性镀铜溶液中氯离子的机理

阐明了用铜粉处理酸性镀铜溶液中氯离子的机理,理论分析和实验表明,在酸性镀铜溶液中,Cu2+离子与铜粉反应生成Cu+离子,同时氯离子与Cu+离子反应生成氯化亚铜沉淀.向镀液中加铜粉1g/L,氯离子的起始质量浓度为174mg/L时,氯离子的去除率为58.9%,而向镀液中加锌粉1g/L,氯离子的去除率为47.0%,用铜粉处理...     

Surface characteristics and adhesion performance of black oxide coated copper substrates with epoxy resins

Black oxide is a conversion coating applied onto the copper substrate to improve its interfacial adhesion with polymeric adhesives. A comprehensive study is made to characterize the black oxide coating using various characterization techniques, including SEM, XPS, AFM, XRD, Auger electron spectroscopy, TEM, D-SIMS, RBS and contact angle measurements. It was found that the oxide coating consisted of cupric and cuprous oxide layers from the top surface to inside. The cuprous oxide layer was formed on the copper crystal surface, on which densely-packed fibrillar cupric oxide grew continuously until saturation. The cupric oxide had a fibrillar structure with high roughness at the nanoscopic scale, whereas the cuprous oxide was rather flat and granular. There was a continuous change in oxide composition with no distinct boundary between the two oxide layers. The bond strength between the epoxy resin and the oxide coated copper substrate increased rapidly at a low level of oxide thickness, and became saturated at thicknesses greater than about 800 nm. There were similar dependences of bond strength on surface roughness, oxide thickness especially of cupric oxide and surface energy, reflecting the importance of these surface characteristics in controlling the interfacial adhesion.     

富勒醇在金属铜中扩散机理的研究

通过研究富勒醇在铜基体中的扩散行为,进而得到了富勒醇分子在多晶金属中的动力学性质。使用无限薄层扩散源向一维半无限大介质中扩散的扩散模型。薄膜的制备采用电沉积的方法,电沉积富勒醇的成分被确定为C₆₀O（OH）₁₂。采用辉光放电光谱法（GDS）、X射线衍射法（XRD）、拉曼光谱法（Raman）等手段对富勒醇在铜基体中的扩散机理以及存在状态进行了表征。结果表明:在250～600℃的条件下,富勒醇在铜基体中的扩散激活能为12.63 kJ·mol^-1·K^-1,且在扩散过程中铜被氧化为+1价。因此,富勒醇在铜基体中的扩散为反应型扩散。     

含铜半导体氧化物的光催化应用进展

应用半导体材料光催化降解污染物和光催化分解水制氢是近几十年来的材料研究热点之一。从拓展光催化材料种类的角度出发,本文对含铜半导体氧化物的基本性质、制备方法及其在光催化方面的应用情况进行了综述。所涉及的氧化物包括含一价铜的氧化亚铜和铜铁矿类复合氧化物,以及含二价铜的氧化铜和尖晶石类复合氧化物。指出将含铜p型半导体氧化物与n型半导体材料复合,制备p-n异质型复合氧化物是有前途的研发方向。