Copper In Aqueous Solution Research Articles

Some experiments regarding the corrosion inhibition of copper by benzotriazole and potassium ethyl xanthate

It has recently been reported that the association of benzotriazole with potassium ethyl xanthate (BTA + KEX) exhibits good inhibitive properties against the corrosion of copper in aqueous solutions containing 0.1 M NaCl [ 1,2]. Moreover, it has been shown that this selective composition appears to be one of the best of its type for avoiding the localized corrosion of copper [2]. These previous studies were mainly preliminary investigations intended to establish the experimental conditions for a synergistic inhibiting effect for copper corrosion, whilst this communication reports new results related to the formation of a surface complex and the nature of the passive film formed on copper. The effectiveness of the resulting protective film against corrosion in environments which do not contain a BTA + KEX reservoir is also investigated.

Hexane-extracted spent bleaching earth as a sorbent for copper in aqueous solution.

Hexane-extracted spent bleaching earth as a sorbent for copper in aqueous solution.

Column Preconcentration of Trace Amounts of Copper on Activated Carbon from Natural Water Samples

Abstract A method has been established for enrichment of trace amounts of copper in aqueous solutions on an activated carbon column. Copper was quantitatively retained on a chromatographic column packed with activated carbon, after complexation with 1-nitroso-2-naphthol or hexamethylene dithiocarbamate and elution with 2 M HCl in acetone. The developed method was used for the determination of trace amounts of copper in water samples with good results. (Recoveries between 95-101%, relative standard deviations 3-5%)

Indirect flame atomic absorption detection for the liquid chromatographic separation of alkaline metals.

Alkaline metals and ammonium ion are separated by cationic exchange liquid chromatography using a 60 microg ml(-1) aqueous copper solution as the mobile phase at 1.5 ml min(-1). Detection is carried out by measuring copper with an atomic absorption spectrometer directly interfaced to the chromatograph. A simple T-piece is used to compensate the difference between the nebulizer uptake rate and the chromatographic flow-rate with air. The method is applicable to the analysis of alkaline metals and ammonium in waters. Average recovery ( n = 16) was 100.3 +/- 4.0%.

Synthesis and characterisation of copper(II) hydroxide gels

The formation of copper(II) hydroxide gels from aqueous precursors requires very critical conditions. Gels have been obtained by adding ammonia to aqueous solutions of copper(II) acetate, in the presence of a small amount of sulphate ions. Other salts (chloride, nitrate, sulphate) or bases (NaOH, KOH) lead to precipitation rather than gelation. These gels are actually made of an intimate mixture of acetate-based organic/inorganic polymers and nanometric posjnakite crystals Cu4(OH)6(SO4) · H2O. Acetate ions and ammonia can be partially removed upon washing, which after drying leads to crystalline copper(II) hydroxide needles deposited on a strongly oriented layer of posjnakite crystals. A theoretical model based on the electronegativity equalisation principle is used to describe these experimental results. It provides a better understanding of the role of complexing anions during the formation of condensed phases.

ChemInform Abstract: Corrosion and Inhibition Studies of Copper in Aqueous Solutions of Formic Acid and Acetic Acid.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Corrosion and inhibition studies of copper in aqueous solutions of formic acid and acetic acid

Corrosion behaviour of copper has been investigated in different compositions of formic acid and acetic acid at 30 °C by a potentiostatic method. The maximum corrosion rate was found in 20–40 mol/o formic acid and in 20 mol/o acetic acid in aqueous solution mixtures. The corrosion rate depended on the concentration of either acid. Formic acid is observed to be more corrosive than acetic acid. The metal exhibited active-passive behaviour in the concentration range of 30–70 mol/o of HCOOH acid in the solution mixture. A short passivity range of potential with a high passivity current density was observed for the metal in the solution mixtures of HCOOH acid while in solution mixtures of acetic acid the metal exhibited only active dissolution. Some organometallic compounds, viz. Bu 2SnCl 2, PhSnCl 3, Ph 2SnCl 2, Ph 3SnCl have been subjected to inhibition studies in the aqueous solution mixture (20 mol/o) of either acid. Among the inhibitors used Ph 3SnCl functions as a better inhibitor in both acids. A strong interaction between the inhibitor and corroding surface of copper is speculated due to adsorption of the inhibitor.

The solute and aquaion structure in a concentrated aqueous solution of copper(II) chloride

Neutron diffraction experiments were carried out on isotopically labelled copper chloride (CuCl2) salt in a 4 molal aqueous solution. The first- and second-order isotopic difference methods were used to obtain structural information on the hydration structure of the Cu2+ and Cl- ions and to calculate the pair distribution functions gCuCl(r) and gClCl(r) The results confirm the highly distorted nearest-neighbour coordination of Cu2+, and give direct evidence that Cu-Cl contacts exist over a range 2.3<or=r (AA)<or=3.5. Analysis of gClCl(r) gives consistent information with that of gCuCl(r) and shows that direct contacts also exist between Cl- ions, over the range 2.8<or=r (AA)<or=4.2.

Inorganic, physicochemical, and microbial aspects of copper corrosion: literature survey

AbstractA literature survey on the corrosion of copper in aqueous solutions, with particular relevance to potable water, is presented. Coverage is of inorganic and physicochemical aspects of copper corrosion, namely those dealing with the thermodynamics of copper corrosion reactions, oxygen reduction at copper surfaces, and the photoelectrochemistry of the copper-copper oxide-electrolyte, system. Microbially induced pitting corrosion and transport in associated biomembranes are also considered.

Bis(µ-2-cyanoguanidine)-bis[(2-cyanoguanidine)copper(I)], a planar dimeric cation containing co-ordinatively unsaturated copper(I)

The air- and moisture-stable copper(I) salts [Cu2(µ-cnge)2(cnge)2]X·2H2O (cnge = 2-cyanoguanidine; X = S2O62–) or SO42– have been prepared by sodium sulfite reduction of aqueous solutions of copper(II) chloride containing cnge. The two salts have been structurally characterised by single-crystal X-ray diffraction methods. The dithionate structure (triclinic, space group P, a= 7.320, b= 7.315, c= 12.765 A, α= 97.10, β= 118.91, γ= 92.93°) is more symmetrical than that of the sulfate (monoclinic, space group P21/c, a= 6.920, b= 14.951, c= 21.042 A, β= 95.17°). Nonetheless, the two [Cu2(µ-cnge)2(cnge)2]2+ cations are very similar. They contain two trigonal-planar copper(I) atoms bridged by two cnge molecules and terminally co-ordinated by a single cnge molecule. To minimise interaction between the in-plane π systems of the bridging cnge molecules, the latter are separated by ca. 3.1 A and angled such that they lie on two essentially parallel planes separated by ca. 0.75 A. The perturbation of the IR spectrum of cnge on co-ordination is dependent not on the co-ordination type (bridging, terminal) but on the strength of its co-ordination to the metal.

In-laboratory stopped-flow extended x-ray absorption fine structure apparatus in the dispersive mode for determination of the structure of short-lived intermediates

We have constructed an in-laboratory stopped-flow extended x-ray absorption fine structure (EXAFS) apparatus by combining laboratory EXAFS equipment in the dispersive mode and a stopped-flow unit with two 150-μm-thick boron nitride windows. The rotating anode x-ray generator with a Mo target was used as an x-ray source. The self-scanning photodiode array was adopted as a position sensitive-linear x-ray detector. In order to obtain a suitable x-ray flux intensity, the accumulation of weak intensities during a short gate time was carried out by repeating the measurements. We have confirmed the performance of our apparatus by repeatedly measuring a number of static EXAFS spectra of 0.20 mol dm−3 aqueous solution of copper(II) sulfate. By use of our newly developed apparatus, we have succeeded in the direct determination of the structure of the reaction intermediate, the heterodinuclear copper(II)/mercury(II) complex, formed in the copper(II) ion incorporation into the homodinuclear mercury(II) complex of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphine.

Carbon monoxide (CO) gas sensitivity of CuO-infiltrated ZnO ceramics

Distinction of carbon monoxide (CO) gas from other combustible gases (especially from H 2 gas) is difficult using conventional SnO2-based ceramic sensors. Special methods, such as measurements under periodic temperature cycling between 100 and 300 °C, are required for CO gas sensing by SnO2based ceramic sensors [1]. A heterocontact of pand n-type semiconducting ceramics is one type of sensor using an interface [2-5]. For making heterocontacts, sintered ceramics of p-type and n-type semiconductors are physically contacted by pressing. In these sensors, the contact points are open to atmosphere gases due to the surface roughness, and the gas phases can react at the interface. This reaction changes the electrical properties of the interface, so that the devices can be used as gas sensors. In previous experiments, a CuO/ZnO sensor has shown excellent CO gas selectivity and a tunable sensing property by control of the applied bias voltages [5, 6]. The preparation of the ceramic contacts is simple, but these contacts do not provide the quantitative reproducibilities important for industrial gas sensors. To make stable p-n contacts, CuO/ZnO thin films were prepared by the sputtering method. This showed sensing properties for humidity and CO gas similar to those of the ceramic heterocontact, but CO gas sensitivity is not high due to the small open-interface area [7, 8]. In the present study, in order to increase the contact area and improve the reproducibility of the CO gas sensing properties, a ZnO-CuO composite was prepared by infiltration of aqueous solution of copper into porous ZnO, and firing. Microstructure and gas sensitivities for CO and H2 gases were examined for the CuO-infiltrated ZnO ceramics. Powder of ZnO (99.99% purity) was pressed into rectangular bars of 5 x 3 x 15 mm at 98 MPa, and sintered at 700 °C for 3 h. The relative density of the ZnO ceramics was 70-80% of the theoretical value. An aqueous solution of copper was obtained from 99.9% cupric nitrate (Cu(NO3)23H20; Kojundo Chemical). A part of the ZnO ceramics was dipped into 0.7 N cupric solution and fired at 600 °C for 1 h. The firing temperature was determined from the results of differential thermal analysis (DTA) which shows three endothermic peaks at 109 °C, 223 °C and 435 °C. Phases in the sample were confirmed

Colloidal copper in aqueous solutions: radiation-chemical reduction, mechanism of formation, and properties

Colloidal copper has been obtained by γ-irradiation of aqueous solutions of copper (II) perchlorate in the presence of alcohol and polyethyleneimine (PEI). The sols are spherical particles about 4 nm in diameter, which are quickly oxidized by oxygen or other oxidants. When CuII is not entirely incorporated into the complex with PEI, disproportionation of CuI aqua complexes formed affords the metal, along with Cu2O. Reduction of the PEI complex of CuI by hydrated electrons gives only colloidal copper. The copper ions can be reduced on the surface of silver sols. Optical parameters of the resulting bimetallic particles have been studied. The presence of copper ions leads to broadening of the absorption band associated with the silver sols and shifts it to the UV region, which is due to the transfer of electrons from copper to silver. Three copper monolayers are enough to cause plasmon absorption of colloidal copper.

Determination of Ultratrace Amounts of Copper and Cadmium in Seawater by Graphite Furnace Atomic Absorption Spectrometry with Flow-Injection Semi On-line Preconcentration

Methods are described for the determination of ultratrace amounts of copper and cadmium in seawater by graphite furnace atomic absorption spectrometry with flow-injection, microcolumn preconcentration. A new type of C 18 column loaded with sodium diethyldithiocarbamate (sodium-DDC) was used to extract copper and cadmium from seawater as the DDC chelates. The analytical effects of the pH of the mixture of the sample and sodium-DDC solutions and the concentration of the chelating reagent were studied. Sodium-DDC-loaded columns and unloaded C 18 columns with different shapes and volumes were compared. To determine copper in seawater, a simple aqueous calibration was made with a mixture of palladium and magnesium nitrate as a matrix modifier, while for cadmium no matrix modifier was necessary. This method required only small seawater volumes, 600 and 400 μl for the determination of copper and cadmium respectively, with preconcentration factors of 15-fold for copper and 10-fold for cadmium. Detection limits for the preconcentration of aqueous solutions of copper and cadmium were 0.024 and 0.004 μg liter −1 (3σ), respectively. Results for determinations of copper and cadmium in National Research Council of Canada, CASS-2, Nearshore Seawater Reference Material showed no significant differences between the certified values and the measured values, based on Student′s t test at the 95% confidence level. The relative standard deviations of the various measurements varied between 2 and 8%.

Underpotential deposition of thallium(I) on electropolished copper in aqueous solutions

The underpotential deposition (UPD) of thallium on electropolished copper electrodes was examined in aqueous solutions of chloride, perchlorate and sulphate base electrolytes. Two distinct UPD peaks were observed and their respective charges of formation are reported. The dependence of the peak potential E p, the peak pseudocapacitance C p and the peak half-width Δ E 1 2 for the first monolayer UPD peak were analysed in detail according to the method proposed by Conway and coworkers. The role of different anionic effects on the adsorption mechanism of formation of the first monolayer is described. Analyses of cyclic voltammetry data and current—time transients obtained by potentiostatic pulse techniques suggest that the second UPD peak is formed by an instantaneous nucleation and growth mechanism. Results of the pH effects on the main UPD peak of Tl on Cu are presented and it is shown that, at high pH values, the formation of copper oxide/hydroxide does not hinder the full monolayer underpotential deposition of thallium.

ホスホン酸をインヒビターとして含む水溶液中における銅の孔食について

ホスホン酸をインヒビターとして含む水溶液中における銅の孔食について

The effect of Cu(II) on the electro-olfactogram (EOG) of the Atlantic salmon ( Salmo salar L) in artificial freshwater of varying inorganic carbon concentrations

The effect of inorganic copper species was studied by recording the receptor potential, electro-olfactogram (EOG), from the olfactory epithelium of Atlantic salmon ( Salmo salar L). In a series of experiments, the olfactory organ was irrigated with aqueous copper solutions with concentrations of the free cupric ion (Cu 2+) ranging from 0.2 to 9.7 μ M. The diverse copper species were created by varying the amount of bicarbonate (NaHCO 3) in artificial freshwater solutions of equal total copper concentrations. In general, these copper solutions induced a slow depolarization of the baseline followed by a hyperpolarization. The amplitudes of these variations in baseline potentials increased with increasing concentrations of Cu 2+ ion, i.e., decreasing concentrations of NaHCO 3. Stimulating the olfactory epithelium with l-alanine during the copper exposure evoked atypical EOG responses. The amplitudes and form of the EOGs changed drastically with increasing Cu 2+ concentrations, with significant correlation between the reduction in EOG amplitudes and the Cu 2+ concentration. The results indicate that among the copper species tested the toxic effect is caused mainly by the dissolved Cu 2+ ion. The results also suggest that the Cu 2+ ion exerts its toxic effects on the transduction mechanisms of the olfactory receptor cells. The different EOG profiles obtained in response to varying Cu 2+ concentrations indicate that this ion affects the transduction mechanisms at different stages.

Physical properties of graft copolymer-metal complexes obtained by radiation grafting onto poly(tetrafluoroethylene-co-perfluorovinyl ether)

Grafting of aqueous acrylic acid onto poly(tetrafluoroethylene-co-perfluorovinyl ether) films has been carried out using γ-irradiation. Copper and chromium complexes have been prepared by treating the grafted films with aqueous solutions of copper and chromium sulphates. The formation of polymer/metal complexes has been confirmed spectrophotometrically by u.v. and colour measurements. Electrical and mechanical properties of films of the complexes have been studied. Thermal analysis and study of the effect of u.v. on the polymer metal complexes have been also undertaken.

Determination of trace amounts of copper with extraction–photoacoustic spectrometry

A sensitive method for the determination of copper in aqueous solution by pulsed laser-induced photoacoustic spectrometry after extraction is described. The copper is chelated with 1,5-diphenylcarbazide in chloroform and extracted into the chloroform phase. The optimum extraction conditions were found experimentally. By using the stepwise dilution method, the minimum absorbance that could be measured was 8.5 × 10–6 at 6.2 mJ per pulse; this corresponds to 6.9 × 10–3µg l–1 of copper in chloroform. The relative standard deviation for ten measurements of an absorbance of 7.8 × 10–3 at 0.7 mJ is 1.5%. Application of the method to the determination of copper in biological samples is also described. The results obtained were compared with those given by atomic absorption spectrometry.

The Design of Amino Hydroxamic Metal Chelates and Their Activity in Biological Systems. Formation Constants between 2-Amino-4-methylpentanehydroxamic Acid with Proton, Copper(II), and Iron(III) in Aqueous Solution

Abstract The complex-formation equilibria and relative stability constants of species present in aqueous solution of copper(II) and iron(III) with “l-leucinehydroxamic acid” (2-amino-4-methylpentanehydroxamic acid, ahmpe) have been determined by using potentiometric and spectrophotometric titrations in 0.5 mol dm−3 KCl solution at 25°C. Their acid-base reaction stoicheiometries have been evaluated and the protonation constants calculated from potentiometric data with the aid of the GAUSS Z and SUPERQUAD programs. The complex formation constants have been determined by using SQUAD (absorbance data), SUPERQUAD and STBLTY (potentiometric data) programs. The ligand is bound to the metal ions through the coordination of the N atoms of the α-amino group and the deprotonated –NHO− group in copper(II)–ahmpe system. For iron(III)–ahmpe system the coordination is referred to oxygen atoms of carboxylate and hydroxamate moieties. The UV-visible studies provide important evidence for the formation of several complex species depending on the pH. The experimental curves [ε=f(λ)], deduced from refinement of absorbance data with the program SQUAD, have been split up into precisely positioned absorption bands by Gaussian analysis using a nonlinear least-squares computer program NLIN. So the solution electronic spectra have been also employed to estimate the coordination sphere and have let us to suppose a weak tetragonal coordination [CuL2(H2O)2] and octahedral for Fe3+ complexes. The determination of formation constants and the coordination pattern proposed have a great interest in terms of metal chelate structures and their important role in biological systems.