Cupric Chloride Solution Research Articles

Redox potential characteristics of cupric chloride solutions

The nature of the redox potential in concentrated cupric chloride solutions where [NaCl] = 280 g/L and [Cu 2+] = 10–40 g/L was studied at temperatures 25–85 °C for 49 days. The redox potential of the solution was studied as a function of solution storage time, temperature and initial cupric chloride concentration. Measured redox potential values varied in the range 0.56–0.75 V vs. Ag/AgCl, increasing with increasing total copper concentration and temperature. The rate of reduction of cupric to cuprous species was highest in the most concentrated solution and occurred in 5 days, with the concentration of copper species 40 g/L. The solutions having initial copper concentrations of 30, 20 and 10 g/L reached steady state after 20, 26 and 26 days, respectively. The standard electrode potential, E o, in concentrated cupric chloride solution was determined using the Nernst equation. The form of cuprous complex was proposed on the basis of the value of E o, since the cupric/cuprous standard electrode potentials divide clearly in two groups. The E o for redox couples, with cuprous present as a chloro-complex form, is a minimum of 0.3 V higher than the E o for redox pairs with uncomplexed cuprous ions. E o value for the redox pair existing in a HydroCopper ® type environment was calculated to be − 0.039 (± 0.121) V vs. Ag/AgCl. This suggests that in a very concentrated cupric chloride solution without any additives, not all cuprous ions present are complexed with chlorides.

REACTION PRODUCT LAYER ON CHALCOPYRITE IN CUPRIC CHLORIDE LEACHING

During the leaching of chalcopyrite in cupric chloride solutions, a reaction product layer forms on the mineral surface. In the present work, the formation and the composition of the reaction product layer on solid stationary chalcopyrite was studied in a chemical environment similar to that of the HydroCopper® process. The effect of the process parameters on the reaction product layer was investigated. Electrochemical measurements, including A.C. impedance spectroscopy, were carried out and an equivalent circuit was used to estimate the surface parameters of the reaction product layer, such as resistance, capacitance and porosity. Scanning electron microscopy was used to complement the electrochemical measurements. The results suggest that at pH = 1, a fragile more resistive elemental sulphur layer forms, whereas at pH = 3, a porous less resistive FeOOH layer is formed.Lors de la lixiviation de la chalcopyrite en solutions de chlorure cuivrique, une couche de produit de reaction se forme a la surface du mineral. Dans le present travail, on a etudie la formation et la composition de la couche du produit de reaction sur de la chalcopyrite solide stationnaire dans un environnement chimique similaire a celui du procede d’HydroCopper®. On a etudie l’effet des parametres du procede sur la couche de produit de reaction. On a effectue des mesures electrochimiques, incluant la spectroscopie a impedance A.C., et l’on a utilise un circuit equivalent pour estimer les parametres de surface de la couche de produit de reaction, comme la resistance, la capacitance et la porosite. On a utilise la microscopie electronique a balayage pour completer les mesures electrochimiques. Les resultats suggerent qu’a un pH = 1, une couche fragile de soufre elementaire plus resistive se forme, alors qu’a un pH = 3, une couche poreuse moins resistive de FeOOH est formee.

Evaluation of an Anaerobic Granule Biosensor for Upset Early Warning Detection

In this study a porous pot reactor was used to simulate an activated sludge stage and an anaerobic granule biosensor (AGB), as an upset early warning system for activated sludge treatment process, was configured in a down-flow mode with a side-stream of the influent wastewater fed to the top. The hydraulic retention time (HRT) for the porous pot and AGB systems was 12 hours and 6 hours, respectively. The influent was made up of synthetic wastewater. In the first group of toxic loading tests, the prepared cupric chloride solutions were separately injected into both the porous pot and AGB systems at six different concentrations (5, 10, 15, 20, 30, and 45mg Cu/L), and phenol solutions were used at four different concentrations (10, 20, 30, and 45mg phenol/L) in the second group of toxic loading tests. In addition, a control study was included for reference. The porous pot reactor and AGB were monitored for pH, ORP, COD, solids, and ammonia concentrations following a simulated toxic event. The COD removal efficiency of porous pot system decreased dramatically in response to the addition of Cu and phenol. The greatest decrease in COD removal efficiency was from 92% to 52% at a Cu concentration of 30 mg/L, and was from 98% to 76% at a phenol concentration of 45mg/L. The longest time of COD removal efficiency continuous decreasing was 23 hours at a Cu concentration of 45 mg/L, and 7 hours at a phenol concentration of 10mg/L. Similar to the response in COD removal, the ammonia removal efficiency decreased significantly after the Cu shock loading. As the porous pot reactor was challenged with the Cu or phenol shock load, the AGB received an equivalent dose. The most sensitive parameter reflecting the toxic shock load in the AGB was the ORP. The ORP changed more rapidly and uniformly than the pH over both the range of Cu concentrations and phenol concentration tested. The shortest response time to

COPPER RECOVERY FROM SPENT ETCHANT CUPRIC CHLORIDE SOLUTION BY ELECTROWINNING METHOD

COPPER RECOVERY FROM SPENT ETCHANT CUPRIC CHLORIDE SOLUTION BY ELECTROWINNING METHOD

Leaching of complex sulphide concentrate in acidic cupric chloride solutions

The chemical analysis of a complex sulphide concentrate by emission spectrometry and X-ray diffraction shows that it contains essentially copper, lead, zinc and iron in the form of chalcopyrite, sphalerite and galena. A small amount of pyrite is also present in the ore but does not be detected with X-ray diffraction. The cupric chloride leaching of the sulphide concentrate at various durations and solid/liquid ratios at 100 °C shows that the rate of dissolution of the ore is the fastest in the first several hours, and after 12 h it does not evolve significantly. If oxygen is excluded from the aqueous cupric chloride solution during the leaching experiment at 100 °C, the pyrite in the ore will not be leached. The determination of principal dissolved metals in the leaching liquor by flame atomic absorption spectrometry, and the chemical analysis of solid residues by emission spectrometry and X-ray diffraction allow to conclude that the rate of dissolution of the minerals contained in the complex sulphide concentrate are in the order of galena >sphalerite>chalcopyrite.

H 2S Removal with Cupric Chloride for Producing Sulfur

A novel technology of removing H 2S with cupric chloride solution was developed in this paper. Cupric as the form of CuS deposition, the CuS produced was then oxidized by excessive cupric ion in another reactor meanwhile cupric ion that has been consumed can be recovered by the oxidization of CuCl − 2 with oxygen in air, and the solution can be circulated. Moreover, the leaching kinetics of CuS by cupric ion was studied. The removal efficiency of H 2S is close to 100%, and the required operating condition is mild. Compared with other wet oxidization methods, no raw material is consumed except O 2 in air, the process has no secondary pollution and no problem of degradation and scale, and the absorbent is much stable and reliable.

Cathodic reactions of Cu 2+ in cupric chloride solution

In this study we demonstrate the kinetics of Cu 2+ reduction in concentrated cupric chloride solutions. Experiments were carried out near the boiling point of the solution ([NaCl] = 280 g/l and [Cu 2+] = 1–40 g/l) at T = 90 °C, atmospheric pressure, pH = 2. Electrochemical methods such as cathodic polarization curves and cyclic voltammetry were used to investigate the cathodic reactions of copper complexes. To identify the nature and the rate-controlling steps of the reactions, rotating disk electrode (RDE) experiments were conducted. The chemical environment studied was similar to that of the Outokumpu HydroCopper TM process, which uses a cupric chloride solution to leach copper from the mineral chalcopyrite. The results suggest that the cathodic reactions are the reduction of [CuCl] + to the complex [CuCl 3] 2−, the reduction of [CuCl 3] 2− to solid copper and hydrogen evolution. The diffusion coefficient and the unit rate constants for the solution species were calculated. The exchange current density and rate constant for electron transfer were also estimated. A simulation was made of the cathodic polarization curve and it was in good agreement with the experimental data.

Effect of NaCl concentration and particle size on chalcopyrite leaching in cupric chloride solution

The paper summarizes results of investigation on the effect of NaCl addition to the acidified cupric chloride leaching solution as well as the effect of the particle size (surface area) of chalcopyrite on the kinetics leaching. While NaCl addition has a definitely positive effect on the leaching rate, the effect of particle size is almost negligible. The experiments conducted under this investigation showed good agreement with the opinion stated in the literature that the major effect of NaCl presence results from the formation of complexes. The negligible effect of chalcopyrite particle size on the leaching kinetics suggests that, at least for the metal recovery obtained in our experiments, the chalcopyrite particles do not become covered by the solid layer that would slow down the reaction.

Leaching of chalcopyrite in cupric chloride solution

Outokumpu HydroCopper™ technology was developed by Outokumpu Research. It is a novel copper production method based on the efficient leaching properties of cupric chloride solutions. The leaching is operated at atmospheric pressure, near the boiling point of water in a stirred reactor and the pH is kept between 1.5 and 2.5. In the present work, an electrochemical study of the dissolution behaviour of chalcopyrite, the most common copper mineral, was made in a concentrated sodium chloride solution (250 g/L) with cupric ion concentrations varied in the range 0.09–26.6 g/L. The effects of pH (1–3) and temperature (70–90 °C) were also measured. The rotating disk electrode technique was used to determine the rate-controlling step in the leaching process. The increase in the dissolution rate was observed to be proportional to the increase in the temperature and to the cupric ion concentration with [Cu 2+]>9 g/L. With [Cu 2+]<9 g/L, the cupric ion concentration did not affect the leaching rate. In order to investigate the reaction products of the chalcopyrite dissolution, the electrodes were analysed by scanning electron microscopy. The results suggested that iron oxides, hydroxides and chlorides gathered on the chalcopyrite surface at higher pHs. At lower pHs, chalcopyrite passivated and a sulfur-rich layer was detected on the surface.

Surface cupricated SnO 2–ZnO thick films as a H 2S gas sensor

SnO 2 (95 wt.%)–ZnO(5 wt.%) thick films have been prepared by screen printing and firing process. Sensitivity of these films to H 2S gas was examined. These films are found better sensitive to H 2S gas than pure SnO 2 films. It may be due to porosity created by ZnO into SnO 2 matrix. SnO 2–ZnO film operates at 250 °C while pure SnO 2 at 350 °C to have a maximum sensitivity. SnO 2–ZnO thick films were surface cupricated to give extremely high sensitivity, fast response and recovery to H 2S gas. In cuprication process, SnO 2–ZnO films were dipped into aqueous solution of cupric chloride for different intervals of time and then sintered. A systematic evaluation of CuO species by SEM and EDAX indicates its crucial role in dictating both sensitivity and selectivity. The response and recovery time of SnO 2–ZnO–CuO sensor have also been found to be significantly improved in comparison with SnO 2–ZnO or CuO doped SnO 2 sensors.

Synthesis, Magnetic, and Spectral Studies of Some Mixed‐Ligand Complexes of Copper(II) Involving Diphenic Acid and Pyridine or Aniline Derivatives

New mixed‐ligand hexa‐coordinated diphenato complexes of copper(II) having the general formula [Cu(DPA)(L)2], where DPAH2 = diphenic acid and L = nicotinamide (NICA), 2‐cyanopyridine (2‐CPY), 3‐cyanopyridine (3‐CPY) and 4‐cyanopyridine (4‐CPY) or aniline derivatives, such as, o‐toluidine (o‐TD), m‐toluidine (m‐TD) or o‐phenetidine (o‐PD), have been prepared by the interaction of an aqueous solution of cupric chloride and ethanolic solutions of diphenic acid and the corresponding ligand L, in the mole ratio of 1:1:2. The resulting products have been characterized on the basis of analytical data, molar conductances, magnetic measurements, infrared, electronic and electron spin resonance spectral studies. All of the complexes are thermally stable and behave as non‐electrolytes. A square‐planar geometry has been suggested for these complexes.

Stress metabolites from Corchorus olitorius L. leaves in response to certain stress agents

Five coumarins were found to be produced as phytoalexins (stress metabolites) from the fresh young leaves of Corchorus olitorius L. plant, in response to inoculation with biotic stress agent, such as the spore suspension of the fungus Helminthosporium turcicum and with chemical stress agents, such as aqueous solutions of mercuric chloride and cupric chloride. The five compounds were isolated, purified and subjected to melting point and spectroscopic determinations. They were identified as scopoletin, fraxinol, isopimpinellin, xanthotoxol and peucedanol. They were tested for their antimicrobial activities. The volatile components of the natural fresh leaves and the cupric chloride-treated leaves were prepared and subjected to GC/MS analysis. Fifty five and 49 components were identified in the control and treated leaves, respectively. cis-3-Hexen-1-ol, cis-4-hexen-1-ol, terpinolene, sabinene and phytol were the major compounds in the control leaves, while those of the treated leaves were cis-4-hexen-1-ol, cis-3-hexen-1-ol, tetradecanal and phytol. The percentage of the total oxygenated compounds were found to be increased in the cupric chloride-treated leaves much more than the control leaves (77.3 and 47.4%, respectively).

Preparation of copper oxide thin film by the sol–gel-like dip technique and study of their structural and optical properties

Copper oxide films are prepared using a methanolic solution of cupric chloride (CuCl 2 · 2H 2O) by the sol–gel-like dip technique at different baking temperatures. XRD study confirms that the films are of Cu 2O phase when prepared at a baking temperature of 360°C and CuO phase when prepared at 400–500°C baking temperature. The optical direct band gap energies for Cu 2O and CuO films calculated from optical absorption measurements are 2.10 and 1.90 eV, respectively, which are quite comparable with the reported values.

SUSCEPTIBILITY OF THE EGGS OF THE PEST SLUG DEROCERAS RETICULATUM TO CONTACT WITH METAL SALTS

Laboratory research is reported in which eggs of the pest slug Deroceras reticulatum were incubated on filter paper moistened with solutions of cupric sulphate, aluminium sulphate, ferric chloride and zinc sulphate at different concentrations. After four or more days exposure, the median lethal doses (LD50) were below 10 � g metal ion/cm 2 for the four metals tested. Copper showed the highest toxicity with LD50 values below 5 � g metal ion/cm 2

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.

Modelling of copper etching in aerated chloride solutions

The effect of dissolved oxygen on the rate of chemical etching of copper by acidic cuprous chloride solution was investigated numerically for the case of a rotating disc electrode (RDE). Copper dissolution in aerated acidic cupric chloride solutions of composition 3.5M CuCl2 + 0.5M HCl + 0.5M KCl and 3.5M CuCl2+0.5M HCl was investigated with consideration of the instantaneous homogeneous reaction 4CuCl32-+4H++O2rlhar4CuCl 3-+2H2O which takes place within the mass transport boundary layer. It was assumed that CuCl32- and O2 react instantaneously, resulting in the formation of a reaction plane which separated the mass transport boundary layer into two regions: a region adjacent to the electrode where oxygen was depleted, and a region adjacent to the bulk where CuCl32- was absent. A one-dimensional mathematical model was developed to predict the position of the reaction plane. The model accounted for diffusion, migration and fluid flow generated by an RDE and included nine species and five heterogeneous electrochemical reactions. The homogeneous redox reaction served to regenerate the chemical etchant solution and thus enhance the etch rate. With increasing oxygen concentration and rotation rate the reaction plane was found to move closer toward the electrode and thus the etch rate of copper increased. Addition of KCl increased the Cl- content in solution so as to shift the reaction plane toward the bulk.

Electrodeposition of copper from pure cupric chloride hydrochloric acid solutions

Electrodeposition from CuCl2–HCl media has been investigated to establish a clean and direct method of copper extraction from cupric chloride solutions purified by anion exchange. The major difficulties of the process – cathode corrosion, CuCl precipitation and roughness of the deposit – were taken into consideration. To prevent contamination, no chemical agents or additives were used in the electrolyte preparation. The workable range of electrolyte composition was approached from a computer aided stability study of the different aquo- and chloro-complex copper species. Experiments suggested that coordination of the fundamental electrolysis parameters can ensure acceptable copper deposits and current efficiencies. A special method of agitation proved effective in improving the conditions.

Kinetics of millerite dissolution in cupric chloride solutions

Oxidation of millerite by cupric chloride in sodium chloride solutions has been studied as a function of: rate of agitation; leaching time; temperature; acid concentration; and total initial cupric concentration. The reaction has a 0.5 order of dependence on initial cupric concentration in the range 0.0 – 0.5 M. The activation energy for the temperature range 333–363 K was found to be 65.2 kJ/mol with chemical reaction at the mineral surface as the rate-controlling step. The rate expression, for initial cupric concentrations between 0.0 and 0.5 M, is: {1−(1−α) 1 3 } = {9.27 × 10 3·[ Cu(II)] 0.5· r 0 −1 exp( −7.847 × 10 3 T ) }·t according to the shrinking-core model.

Characterization of Films Formed during the Corrosion of Copper in Dilute Solutions of Cupric Chloride

ABSTRACTMicrostructural differences in copper deposited by four techniques commonly used in the microelectronics industry were previously reported. Grain size, preferred orientation, and near surface chemistry were considered. [1] Prediction of the reaction rates were made based on these differences and then correlated with actual measurements. [2] In aerobic conditions the grain size dictated the reaction rate, the smaller the size the faster the rate.[3] The composition of the surface film formed during etching was examined. The trends in chemical concentrations on the surface film vary for each sample, but the relative constituent amounts correlate to the grain size of the original copper samples. Thus, there is further evidence that during exposure to aqueous solutions of cupric chloride, copper corrosion, in terms of both etch rate and film composition, is dictated by grain size of the original copper and not other microstructural factors.

Crystallization test for the detection of head and neck cancer.

Twenty-five patients suffering from head and neck cancer and 25 healthy individuals were subjected to a blood crystallization test with 20% cupric chloride solution and the patterns were compared. In the healthy control group, the typical pattern was an eccentrically placed center of gravity with needles arranged in a radiating fashion, while in the malignant group, there was a transverse bar or transverse formation. The sensitivity of this test procedure was 88%. We therefore conclude that this study is an interesting reliable, economical and above all useful adjunctive for a mass screening programme in the diagnosis of malignant diseases of the head and neck region. The test is based purely on physical phenomena and hence should be performed under controlled physical conditions.