Copper In Aqueous Solution Research Articles

Sonochemical Synthesis and Characterization of Nanocrystalline Paramelaconite in Polyaniline Matrix

A simple method for the fabrication of nanocrystalline Cu4O3 in polyaniline is reported. An aqueous solution of copper(II) acetate and aniline (1:10 mole ratio) is irradiated by ultrasound to produce nanophased Cu4O3 embedded in a polyaniline matrix. The as-prepared Cu4O3-polyaniline is characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). The mechanism for the fabrication of Cu4O3-polyaniline is proposed and discussed. This method is general and works also for the production of nanocrystalline Fe3O4 and Cu2O embedded in polyaniline. This technique is an easy route for the production of other metal oxides embedded in polyaniline as well.

A Chromatographic Effect Observed during Deposition of Cu–Mn Precursors on Active Carbon

The possibility of appearance of a chromatographic effect during the deposition of Cu–Mn precursors on active carbon with a view to obtaining supported oxide catalysts with a definite active phase composition has been investigated. By impregnation of the support with aqueous solutions of copper and manganese nitrates and subsequent drying at 110°, two types of samples have been obtained: one-component and two-component ones. They have been characterized by chemical analysis, IR spectroscopy, EPR analysis, and magnetic and adsorption measurements. It has been established that during the preparation of two-component precursors the chromatographic effect is not very strong. Due to the complex chemical nature of the active carbon surface, the copper and manganese ions are adsorbed at different sites. On the basis of the isoelectric point of the active carbon and the pH value of the impregnating solutions, a scheme for the occurrence of adsorption processes has been proposed. The porous texture of the active carbon permits deposition of the precursor at definite surface sites; due to this it is very promising as a support of two-component oxide catalysts.

Crystal structure of a copper stabilized hydrate of di-2-pyridyl ketone

The addition of a yellow ethanolic solution of di-2-pyridyl ketone to a blue–green aqueous solution of copper(II) bromide produces an exothermic reaction and a brilliant purple solution. Brilliant purple single crystals were obtained from the solution by solvent evaporation and were subjected to a crystal structure determination. The structure of the isolated gem-diol compound stabilized by a transition metal contains two di(2-pyridyl)methanediol ligands bonded to the central copper atom in a distorted octahedral arrangement providing four nitrogen atoms at relatively short bond distances and two oxygen atoms at longer bond distances. In the solid state, both oxygen atoms on each of the gem-diol ligands are protonated.

Effect of Sulfur on the Oxidation of Copper in Aqueous Solution

Combined ultrahigh vacuum electrochemistry is applied to study the effect of sulfur on copper oxidation in aqueous solution. Chronoamperametric studies show that pulsing a Cu electrode modified with ∼0.1 monolayer of adsorbed S results in an approximately 50 s plateau in the current‐time profile after a slight initial decay in current. Following the plateau period, the current‐time profile is observed to exhibit a final phase of current decay. In contrast, a S‐free copper electrode exhibits immediate current decay. X‐ray photoelectron spectroscopy analysis reveals that is the main oxide growing on both S‐free and S‐modified copper surfaces under these conditions. On the S‐free copper surface, oxide covers the surface almost immediately after the pulse. On the S‐modified copper surface, oxide growth continues for ∼70 s after the pulse. The data indicates that the final phase of current decay on the S‐modified Cu surface occurs only when oxide growth is essentially complete. Oxide growth is significantly retarded by the presence of sulfur. © 2000 The Electrochemical Society. All rights reserved.

Synthesis and properties of hydrophilic polymers. Part 7. Preparation, characterization and metal complexation of carboxy-functional polyesters based on poly(ethylene glycol)

Novel water-soluble polyesters with pendant carboxylic groups were synthesized by polycondensation of ethylenediaminetetra-acetic acid (EDTA) dianhydride and diethylenetriaminepenta-acetic acid (DTPA) dianhydride with poly(ethylene glycol)s of different chain-lengths. Two experimental approaches (polycondensation using various solvents and in the melt) were studied, and melt condensation was found to give higher yields of polyesters. The polymeric products were soluble in water, acetone, chloroform and toluene, and were characterized by elemental analysis, IR and NMR spectroscopy. In addition, the carboxyl functionalities were determined by titration and the hydrolytic stability studied as a function of pH. The complexing capacity of the functional polyesters was determined in dependence of pH for copper in aqueous solution using the Liquid-Phase Polymer-Based Retention (LPR) technique and found to be 257 mg g−1 for the EDTA-based copolymer at pH 5 and 230 mg g−1 for the DTPA-based copolymer, respectively. © 1999 Society of Chemical Industry

Prompt and delayed photoejection of hydrated electrons in the UV photolysis of aqueous solutions of copper(I) complexes

The ejection of hydrated electrons from 266-nm laser-photoexcited solutions containing Cu(NH3)+3, CuCl2−3, or CuBr2−3 occurs through two pathways on the nanosecond time scale: a prompt ejection (τ<laser pulsewidth), and a delayed ejection (τ>laser pulsewidth) which follows a first-order rate law. This behavior is consistent with electron ejection from two excited states: the primary CTTS state, and longer-lived triplet species consisting of an exciplex and its precursor. The quantum yields for both prompt and delayed ejection are quite high, in the 0.15–0.4 range.

Integrated electroless metallization for ULSI

In this paper, we present a novel copper interconnect scheme where conducting, barrier and capping layers are deposited by electroless methods. Electroless copper deposition has been demonstrated for sub-0.25 μm metallization on large silicon wafers. In this paper, we extend the use of electroless deposition for the layers under and above the copper. After a short overview of electroless copper and barriers deposition we describe some of the current process modules and the properties of the thin films. Next we review the individual layer properties, describe their integration, and discuss the highlights and problems of the integration of copper, barriers, and capping layers, all deposited by electroless methods. The integrated process features deposition from an aqueous solution of copper and CoW alloys. The metals deposition is due to an electrochemical oxidation-reduction reaction that takes place on the liquid-solid interface. Electroless deposition is autocatalytic and the interconnect materials themselves can serve as seeds for some deposition solutions. In some cases, surface activation is required to initiate the autocatalytic process. We will discuss the issues of the seed layer and will present both ‘wet’ and ‘dry’ seeding methods. The deposition of both copper and the barrier layers is very conformal and we assume that the deposition rate is surface-reaction limited. In addition, we present recent results of the barrier material properties and experimental results of the fully integrated structure with and inlaid-copper technology.

Dimerization of a copper(II) compound with a tetradentate diaminodiamide ligand †

Two types of crystals were isolated from aqueous solutions of copper(II) salts, the tetradentate diaminodiamide ligand H2L1 (H2L1 = 1,8-diamino-3,6-diazaoctane-4,5-dione) and base. Crystal structural analyses revealed that one is the expected [Cu(L1)] and the other is the corresponding dimer [Cu2(L1)2], with the two copper(II) chromophores in nearly parallel planes (Cu· · ·Cu distance = 3.35 A; angle between the two planes, θ = 18.6°), where each ligand co-ordinates to both metal centers. Relief of strain, induced by the central, flat, five-membered chelate ring with two amide donors and two fused five-membered rings, and van der Waals attractions may be responsible for the stabilization of the dimer. This is supported by force field calculations which accurately reproduce the experimentally observed structures (RMS = 0.14 (monomer), 0.19 A (dimer)), define them as the lowest strain energy conformers and find a stabilization of the dimer by 24 kJ mol–1 (ΔUstrain = 2Ustrainmonomer – Ustraindimer).

Competitive Sorption of Copper and Nickel Ions from Aqueous Solution Using Peat

Bicomponent aqueous solutions of copper and nickel ions have been used to investigate the sorption of metal ions onto peat. Peat, a low cost sorbent, has shown a high capacity for the sorption of single component metal ions attributed to extensive carboxylic acids within its structure. Copper and nickel ions were selected as typical metals in the effluents of electroplating industries. The effects of competitive sorption in batch systems were studied at various metal ion concentrations. In this study the Butler and Ockrent model was modified using a coefficient, η. Two models were developed based on the interaction coefficient η. The first model incorporates a constant fixed η factor for each metal ion into the Butler-Ockrent equation. The second model incorporates a variable η factor into the Butler-Ockrent equation; this interaction factor varies as a function of sorbent surface coverage. Predicted equilibrium data are found to be in excellent agreement with experimental values using both modified models for various mole ratios of copper and nickel ions in competitive sorption.

Coagulation of Quartz Particles in Aqueous Solutions of Copper(II)

The colloidal stability of quartz suspension was determined over a wide range of pH in aqueous copper nitrate where the state of Cu(II) is changed from mainly aqua ions and monohydroxyl complexes in the acid and neutral pH to polynuclear hydroxo complexes and colloidal precipitated copper hydroxide at higher pH. Two regions of instability were observed and in both cases the particles were shown to have low electrophoretic mobility. In the neutral pH region, the uptake of Cu(II) was sufficient to reduce the mobility of the particles to zero, while in the high-pH region evidence suggested coagulation between precipitated Cu(OH)2and the quartz particles. It was shown that in all cases the coagulation was reversible and that the uptake of Cu(II) was dependent on the uncharged surface hydroxyl density. Studies of the coagulation kinetics showed that extended time scales were involved (several minutes in the neutral pH region to tens of minutes at high pH).

Structural, Spectroscopic, Thermodynamic and Kinetic Properties of Copper(II) Complexes with Tripodal Tetraamines.

Spectroscopic, thermodynamic, and kinetic measurements have been made on aqueous solutions of copper(II) complexes of hexamethylated tren and trimethylated tren (one methylation per primary amine group of tren) with the objective of correlating the influence of geometry (trigonal bipyramidal, evident from UV/vis spectroscopy) and N-alkyl substitution in the ligand on these inherent properties. At 25.0 degrees C the protonation constants of Me(3)tren are not significantly different from those of tren and Me(6)tren, and the stability constant for the Cu(II) complex is of the same order of magnitude as that for the [Cu(tren)(H(2)O)](2+) complex ion. The pK(a) for deprotonation of the coordinated water molecule of [Cu(Me(3)tren)(H(2)O)](2+) is intermediate between the values for the complexes containing the unsubstituted and the fully substituted tren ligand. Substitution (pyridine for water) kinetics measurements employing stopped-flow and temperature-jump methods revealed different patterns of reactivity: pyridine replaces water in [Cu(Me(3)tren)(H(2)O)](2+) with a second-order rate constant of (4.4 +/- 0.8) x 10(2) M(-)(1) s(-)(1) at 25.0 degrees C, whereas the corresponding process for [Cu(Me(6)tren)(H(2)O)](2+) is relatively complex and is discussed in more detail. Substitution in the former complex ion is characterized in the forward and reverse directions, by DeltaH() = 60 +/- 8 and 51.9 +/- 0.9 kJ mol(-)(1), DeltaS() = 5 +/- 27 and -23 +/- 3 J mol(-)(1) K(-)(1), and DeltaV() = -8.7 +/- 4.6 and -6.2 +/- 1.1 cm(3) mol(-)(1), respectively. It is concluded that this reaction follows an I(a) mechanism, similar to that reported for the comparable reaction of [Cu(tren)(H(2)O)](2+). An X-ray structural determination on a crystal of [Cu(2)(Me(3)tren)(2)(CN)](ClO(4))(3).2CH(3)CN demonstrated trigonal bipyramidal geometry about each copper(II) center. As has been found in comparable complexes of tren and Me(6)tren, the axial nitrogen to copper bond is shorter than the equatorial nitrogen-copper bonds, and the angle made by N(axial)-Cu-N(equatorial) is less than 90 degrees (84.6-85.4 degrees ), signifying that each copper ion lies below the plane of the equatorial nitrogen atoms.

Combined effects of copper, desiccation, and frost on the viability of earthworm cocoons

AbstractThe effects of heavy metal pollution on earthworms have been extensively studied, but no studies have examined how earthworms react if they are simultaneously exposed to metal pollution and climatic stress. This question has been addressed in a laboratory study where cocoons ofAporrectodea caliginosaandDendrobaena octaedrawere initially exposed to copper in aqueous solutions of copper chloride and thereafter exposed to realistic degrees of either desiccation or frost. Earthworm embryos absorbed copper in amounts (up to approx. 200 mg/kg dry tissue weight) comparable to concentrations found in various tissues of earthworms from metal‐polluted soils. Desiccation and copper exposure in combination had synergistic effects on survival rates for both species. For example, at full saturation, the NOEC (the highest tested concentration with no statistically significant effect) for copper ofA. caliginosawas 12 mg/L, whereas at 97% relative humidity it was only 6 mg/L. Frost and copper exposure in combination also showed synergistic effects in some experiments. No cocoons ofA. caliginosaexposed to 20 mg copper/L were viable after exposure to −3°C but at 0°C viability was as high as 95%. The same tendency was seen inD. octaedrabut not as clearly as inA. caliginosa.A change of the environmental conditions (moisture, temperature) to increasing severity caused a shift in the statistically derived NOEC toward lower critical values of copper. The involvement of combination effects in ecotoxicological tests could therefore improve risk assessment of soil‐polluting compounds.

Double-layer structure, corrosion and corrosion inhibition of copper in aqueous solution

Double-layer structure, corrosion and corrosion inhibition of copper in aqueous solution

Direct separation of ?-hydroxy acid enantiomers by ligand exchange chromatography

Direct separation of several α-hydroxy acid racemic mixtures was performed by the aid of ligand exchange chromatography using L-hydroxyproline chemically bound to silica stationary phase and aqueous solutions of copper (II) sulphate as a mobile phase. The elution order of the D- and L-enantiomers of α-hydroxy acids is interpreted in terms of a modified Davankov's rule. Several aspects of the Davankov's model of selectand-Cu(II)-selector ternary complexes are discussed based on the theoretical calculations within the quantum mechanical semiempirical and density functional theories. Chirality 10:821–830, 1998. © 1998 Wiley-Liss, Inc.

A Channel-Forming Polyiodide Network in [Cu(dafone)3]I12. A Tris Chelate of Dafone and a New Planar Structure for the I122- Ion (Dafone = 4,5-Diazafluoren-9-one)

Treatment of an aqueous solution of copper(II) acetate, dafone, and KI with I2 in CH2Cl2 leads to the formation of Cu(dafone)3I12 (1). 1 crystallizes in the orthorhombic system, space group Pbcn, with a = 22.902(4) Å, b = 11.104(2) Å, c = 18.992(7) Å, and Z = 4. Cu(dafone)32+ is the first tris chelate of dafone and is stabilized by a channel-forming network of planar I122- ions. Temperature dependence of the EPR spectrum indicates fluxionality of the cation.

Corrosion Mechanisms and Products of Copper in Aqueous Solutions at Various pH Values

Abstract The corrosion behavior of copper in aqueous solutions of different pH values was investigated using electrochemical and surface analysis methods. It was shown that the corrosion mechanism changed with pH and was associated with morphology of the surf ace films formed. In solution of pH 3, the copper surface was covered with porous corrosion products of cuprous oxide (Cu2O). Corrosion was controlled predominately by diffusion in solution. In solutions of pH 4 to pH 5, formation of cubic Cu2O on the copper surface provided a diffusion barrier to copper dissolution. The anodic process was controlled by a mixed diffusion of copper ions in oxide films and in solution. In solutions of pH 6 to pH 9, the oxide films (Cu2O) became more protective. Diffusion in the oxide films became a rate-determining step of anodic dissolution. In pH 10 solution, a thin, compact Cu2O film formed, and spontaneous passivation was observed. At pH 12 and pH 13, analysis by x-ray photoelectron spectroscopy (XPS) and scanning ...

Removal of Copper in Aqueous Solution by Apple Wastes

Removal of copper from a solution was investigated to evaluate the cation-exchange capacities of apple residues from agricultural wastes. The effects of solution pH, ionic strength, co-ion, ligands, initial metal concentrations, and particle size of apple residues were studied. The optimal pH range for copper removal by apple residues was shown to be from pH 5.5 to 7.0, and the maximum percentage of copper removal was 91.2%. Increasing ionic strength, up to 0.1 N, has little effect on metal uptake. The presence of co-ions such as lead decreases the removal capacity of copper as expected. The presence of ligands, such as EDTA and ammonia, also reduces metal removal efficiency due to the formation of a metal-ligand complexation in solution. Equilibrium of copper sorption was established very rapidly initially and decreased markedly after 1 hour. Equilibrium isotherms of copper fit the Langmuir equation adequately. Column experiments showed that the dynamic capacity of chemically modified apple residues was four to five times higher than that of raw residues which contained acidic groups such as carboxylic and phenolic functional groups. The adsorbed copper ions were completely recovered with three bed volumes of 0.5 N HCl. Thus, modified apple residues could be applied successfully for metal removal from wastewater.

Photochemistry of macrocyclic copper(II) compounds bound to polyelectrolytes

Anionic polyelectrolytes were added to aqueous solutions of copper(II) tetraazamacrocycles to modify their photochemical properties. Steady-state photolysis of solutions containing polycarboxylates, at pH 6.5, showed formation of copper(I) macrocycles with minimal degradation to free copper ions, Cu aq + or Cu aq 2+. Product quantum yields indicated that: (i) the polycarboxylate surrounding helped to enhance the photochemical properties of copper(II) macrocyclic complexes, serving as sacrificial electron donors; and (ii) there was an interaction of the photogenerated carbon dioxide molecules with the copper(I) units, forming long-lived species. Moreover, the polyelectrolyte microenvironment protected the copper(I) macrocycles from prompt conversion by different reaction pathways, such as opening of the macrocycle and hydrolysis. Time resolved experiments helped to elucidate the nature of the reaction intermediates and indicated formation of an adduct between the copper moiety and carbon dioxide.

The corrosion inhibition of copper by potentiostatic anodization in triazinedithiol solutions

The electrochemical behavior of copper in aqueous solutions of triazinedithiols (TDT) has been studied for the purpose of obtaining the optimum electrolysis condition for surface treatment. By potentiokinetic polarization, copper electrode showed anodic current peak at a potential around 1.0 V(SCE) in alkaline TDT solutions. The potential of current peak, E a max , is affected slightly by the types of radicals ( R-). After anodization corrosion resistance of copper was evaluated by both an immersion test and the electrochemical method. Copper showed the highest corrosion resistance when it had been pretreated potentiostatically at E a max in TDT solutions. Potentiokinetic polarization curves of pretreated copper in 3% NaCl showed that corrosion current was suppressed with increasing number of carbon in the hydrophobic radicals, while cathodic branch showed no such dependence indicating the improved performance by anodic treatment.

Determination of copper by zeolite molecular sieve modified electrode

Chemically modified carbon paste electrodes incorporated with zeolite molecular sieves were constructed as sensor electrodes for voltammetric determination of trace copper in aqueous solution. Square wave voltammetric techniques were used to quantify Cu(II) in aqueous solution. The copper response was characterized with respect to electrode composition, cleaning solution, Cu(II) concentration, preconcentration time, pH, and other variables. The peak current was found to be linearly related to the concentration of Cu(II) in the range of 0.3–1.0 mg l −1 with a correlation coefficient of 0.9992. The electrodes were electrochemically sensitive to copper in ammonia buffer solution with a detection limit of 0.074 mgl −1.