Copper Ions In Solution Research Articles

Heavy metal removal from industrial wastewater by clinoptilolite

Clinoptilolite- a natural zeolite has been investigated for the removal of heavy metals from the wastewaters. A pyrex-glass column of 30 mm diameter and 600 mm height was used. The column was filled with the conditioned clinoptilolite of 0.5–1 mm. In the first stage of the research, synthetic wastewater containing single cation 0.02 N and 0.04 N Cu and 0.02 N Fe and Zn solutions were passed through the column. Two liter of 0.02 N Cu and 750 ml of the 0.04 N Cu solution was treated with 100 percent removal efficiency. Clinoptilolite column was regenerated for the reuse when the removal efficiency decreased. The cation exchange capacities were calculated as 1.0663 and 1.5342 meq/g clinoptilolite for 0.02 N and 0.04 N Cu solutions, respectively. In the second stage of this research, the same procedure was repeated with the actual wastewater samples of the equalization and the neutralization tanks of the Telka-Rabak Electrolytic Copper Industry. A volume of 1811 ml of the wastewater of the equalization tank and 180 ml of the neutralization tank wastewater, which had high concentrations of Ni, Zn, Cu and Fe, was treated with 100 percent efficiency. The cation exchange capacities of clinoptilolite for the wastewater of the equalization and the neutralization tanks for Cu were 0.4483 and 0.4274, respectively. It was observed that only one third of the single copper ion solutions were obtained with the actual wastewater having competing ions such as Zn, Fe and Ni. The experimental results also indicate that the clinoptilolite is an effective cation exchanger for the removal of the metals from the wastewater and the removal efficiency is higher when there is not ant competing ions.

Copper modified chitosan for protection of AA-2024

The aim of this study is to examine chitosan, which is a good film former, as a corrosion protective coating for AA-2024-T3 aluminium alloy. The aluminium samples were first anodized to increase adhesion of the subsequently dip coated film from a chitosan–acetic acid solution. To further increase the protective ability of the chitosan coating, the coated samples were immersed in a copper ion solution for 24 h. The copper salts used were sulphate and acetate. The chitosan membranes exposed to copper ion solutions revealed a reduced permeability in comparison with the unexposed samples, and an increase in stability in aqueous solutions, as revealed by a steady state and a high open circuit potential in borax solution. From UV–Vis spectroscopic measurement of the film on ITO glasses, the reduction in permeability of the chitosan film modified by copper ions appears to be associated with copper cross linking within the chitosan structure.

Microfluidic cell with a TiO 2-modified gold electrode irradiated by an UV-LED for in situ photocatalytic decomposition of organic matter and its potentiality for voltammetric analysis of metal ions

A novel microreactor for TiO 2-assisted photocatalysis in a microfluidic electrochemical cell was designed and constructed by a technology that can be reproduced in any chemical laboratory. The cell is obtained by a two-step thermal transfer of laser printed masks onto gold CD-Rs, a subtractive one to define the electrodes, and an additive one to define the channels. The TiO 2 nanoparticles are physically embedded in a gold matrix by electrodeposition from a solution of ions of this metal also containing colloidal suspension of anatase. This modification is conducted in the assembled microfluidic cell, with minimum material and time consumption. A 100 mW UV-LED (365 nm) is focused on the modified electrode and irradiation of the sample in the thin layer microreactor is conducted under stopped flow condition. The Cu–EDTA complex served as model system to demonstrate the in situ photocatalytic digestion of organic matter followed by the voltammetric determination of the metal ion in aqueous solution. The voltammetric wave of 1.0 × 10 −3 mol L −1 Cu(II) in acetate buffer (pH 4.7) at the gold electrode is suppressed by EDTA in the −0.3 to 0.8 vs. Ag/AgCl region. Irradiation of the bare electrode at 365 nm does not recover the wave, while irradiation of the TiO 2-modified gold electrode causes the recovery of the copper wave, proving the photocatalytic destruction of the chelating agent. Diffusion transport to/from the modified electrode rapidly enrolls the whole volume of sample in the thin-layer above the electrode (about 19 nL), so that in less than four minutes the recorded voltammogram become indistinguishable from that of a copper ion solution without EDTA. This novel in situ sample pre-treatment approach is very promising, deserving further research aiming its integration in micro-TAS.

Effect of the displacement reaction on the composition of the magnetic layer in electrodeposited layered nanostructures Co-Cu/Cu and Ni-Cu/Cu

Methods of stripping voltammetry, quartz microgravimetry, and x-ray-fluorescence analysis are employed to explore the copper displacement process on thin electrodeposited layers of pure cobalt and nickel and on deposits of these metals with inclusions of copper. The displacement reaction proceeds at a considerable rate on cobalt in the sulfate and sulfosalicylate solutions and virtually does not proceed on nickel in both the sulfate or sulfate-chloride solutions. An estimate of the rate of the copper displacement reaction following a change in the concentration of copper ions in the solution and in the pH of the sulfosalicylate solution is given. A decrease in the contact exchange rate is facilitated by a decrease in the concentration of copper ions in solution and their participation in the formation of complexes.

Selective extraction and concentration of dispersed copper from dilute solutions of copper and zinc ions with weakly basic aminoanionites

The possibility of selective extraction and multiple concentration of copper in the form of ultrafine precipitate from dilute Cu2+-Zn2+ solutions by using a suitable sorbent and an effective mode of its regeneration was demonstrated. The extraction was performed in the dynamic mode in column-type reactors filled with an aminoanionite as a selective complexing sorbent, the regeneration of which was conducted by chemical reduction of Cu2+ in the ionite after its saturation. It was established that saturation-reduction cycles repeated many times result in the accumulation of metallic copper at the surface and in the bulk of the sorbent. The mechanism of the process includes the formation of complexes of copper and zinc with amino groups of the ionite and the subsequent displacement of Zn2+ ions from the anionite due to its higher affinity to Cu2+ ions followed by the conversion of Cu2+ ions to an unsorbable form (dispersed metallic copper). It was demonstrated that the presence of dispersed copper stimulates the additional sorption of Cu2+ ions via redox conproportionation. This method makes it possible to obtain a degree of concentration of copper ions in three cycles >300% higher than that attainable in the purely ion-exchange mode (without chemical reduction).

EQCM Study of the Influence of Copper Ions on the Adsorption of Polyethylene Glycol and Bis(sodium sulfopropyl) Disulfide at a Copper Cathode

An electrochemical quartz crystal microbalance (EQCM) has been used to examine the role of polyethylene glycol (PEG) and bis (sodiumsulfopropyl) disulfide (SPS) in the deposition of copper from acidified aqueous sulfate solutions containing chloride ions. Neither PEG nor SPS was observed to adsorb on copper at cathodic potentials in the absence of copper ions in solution. When a small amount of copper (principally Cu (II)) was introduced into solution by a double potential step, the adsorption of PEG was observed, as was the inhibition of that adsorption by SPS.

Copper sorption onto a lignocellulosic substrate from wheat bran impregnated with a lipophilic tetraazamacrocycle

The topic of this paper is the impregnation with tetraazamacrocyclic ligands of a lignocellulosic substrate extracted from wheat bran. A preliminary N-functionalization by an alkyl pendant arm makes the cyclic tetraamine ligands lipophilic, so as to ensure their immobilization on the substrate. The macrocyclic ligands thus fixed at the surface of the lignocellulosic substrate interact with copper ions in solution to form complexes, as proven by EPR spectra. The end result is an increased retention capacity of the lignocellulosic substrate for pH values lower than 4. Indeed, while the unmodified lignocellulosic substrate does not retain Cu(II) at pH 3, the impregnated substrate exhibits a retention capacity of 4.13 mg g −1. As a result, this technique of impregnation seems to be a good solution to extend the application field of lignocellulosic substrates, and consider their use in the treatment of acidic effluents.

Catalytic Hydrogenation of Halosteroidal Derivatives by Bipyridine or Phenanthroline Complexes of Copper(II) in Hydrazine Aqueous Media

We report two synthetic systems, Cu(Bpy)2+ and Cu(Phen)2+, for catalytic hydrogenation of steroidal haloalkenes in the presence of hydrazine and air. Thesestudies demonstrated that the selective hydrogenation is faster for the 1,10‐phenanthroline–Cu(II) system because forming more stable copper complex are formed, leaving fewer free copper ions in solution. Evidence also supports that the catalytic power of Cu(II) ions can be tuned moderately through the addition of bidentate ligand, Bpy or Phen.

The chemistry of nitrogen coordinated tertiary carboxamides: a spectroscopic study on bis(picolyl)amidecopper(ii) complexes

Metal coordination of the electrically neutral nitrogen atom of a tertiary carboxamide reduces the barrier to C-N-bond rotation and activates the amide towards methanolysis. X-Ray crystallographic studies indicate that this reactivity is correlated to a lifting of the amide resonance structure and concurrent pyramidalization at nitrogen. However, mechanistic data in solution have not been obtained. It became evident that structural mobility is characteristic of the complexes and the crystallographic data do not fully account for relevant reactive species. In this report we summarize IR, UV-vis, and EPR spectra of amide nitrogen coordinated bis(picolyl)amide complexes with copper(II) triflate and copper(II) chloride. A comparison between spectra sampled in the aprotic solvents dichloromethane and acetonitrile, as well as under methanolysis conditions reveals the nature of several species formed in solution. The key reactions are (I) ligand exchange involving either CH3CN or CH3OH, or, in IR experiments, bromide ions from KBr, (II) coordination-dissociation equilibria involving the urethane protecting groups of amino acid substituted ligands Boc-Xaa-bpa (Boc = tert-butoxycarbonyl, Xaa = glycine, alanine, and leucine, respectively, bpa = bis(picolyl)amine), (III) dissociation of a chloro ligand from LCuCl2 complexes and formation of square-pyramidal complex cations [LCuCl]+, and finally (IV) complete dissociation of the polydentate tertiary amide ligand to produce free copper ions in solution. Taken together, the results provide a fairly detailed qualitative picture of the processes which accompany the amide bond methanolysis.

Copper Ion-Selective Fluorescent Sensor Based on the Inner Filter Effect Using a Spiropyran Derivative

A highly selective copper(II) ion fluorescent sensor has been designed based on the UV-visible absorption of a spiropyran derivative coupled with the use of a metal porphyrin operative on the fluorescence inner filter effect. Spiropyrans, which combine the characteristics of metal binding and signal transduction, have been widely utilized in cationic ion recognition by UV-visible spectroscopy. In the present work, the viability of converting the absorption signal of the spiropyran molecule into a fluorescence signal was explored. On account of overlap of the absorption band of the spiropyran (lambda(abs) = 547 nm) in the presence of copper ion with the Q-band of an added fluorophore, zinc meso-tetraphenylporphyrin (lambda(abs) = 556 nm), the effective light absorbed by the porphyrin and concomitantly the emitted light intensity vary as a result of varying absorption of the spiropyran via fluorescence inner filter effect. The metal binding characteristic of the spiropyran presents an excellent selectivity for copper ion in comparison with several other heavy or transition metal ions. Since the changes in the absorbance of the absorber translate into exponential changes in fluorescence of the fluorophore, the novelty of the present device is that the analytical signal is more sensitive over that of the absorptiometry or that of the fluorometry using one single dye. To realize a practical fluorescent sensor, both the absorber and fluorophore were immobilized in a plasticized poly(vinyl chloride) membrane, and the sensing characteristics of the membrane for copper ion were investigated. The sensor is useful for measuring Cu2+ at concentrations ranging from 7.5 x 10(-7) to 3.6 x 10(-5) M with a detection limit of 1.5 x 10(-7) M. The sensor is chemically reversible, the fluorescence was switched off by immersing the membrane in copper ion solution and switched on by washing it with EDTA solution.

Optical induction of magnetization and observation of fast spin dynamics in aqueous solutions of copper ions

Optically induced magnetization and its fast dynamics in aqueous solutions of transition-metal ions is studied by the polarization spectroscopy with the pump-probe technique. The fast spin dynamics in solutions at room temperature, which cannot be detected by the conventional magnetic-resonance methods, was observed by an all-optical method. A circularly polarized pump pulse creates the magnetization in the ground state of the copper ions in aqueous solutions of copper sulfate, and the time evolution of the magnetization in the subnanosecond region is monitored through the change of the polarization of the probe pulse. Quantum-beat free-induction decay signals are observed in transverse magnetic fields, whose Fourier transform gives the ESR spectra. The observed concentration dependence of the relaxation rate in no external magnetic field is interpreted by the spin cross relaxation due to the magnetic dipole interaction between the copper ions.

Organosilica Copolymers for the Adsorption and Separation of Multiple Pollutants

Benzene, diethylbenzene, and ethylenediamine-bridged bistrialkoxy precursors were used in the synthesis of multifunctional PMO copolymers for the adsorption of phenols and metal ions. Polyoxyethylene(10) stearyl ether (Brij 76) was used as the structure director with the surfactant template approach in the synthesis. The resulting PMO copolymers with two or more bridging groups have been characterized by nitrogen gas adsorption, powder X-ray diffraction, and 13C and 29Si solid-state NMR. These organosilicas exhibit large surface areas, narrow pore size distributions, large total pore volumes, and pore ordering consistent with well ordered, hexagonally packed p6mm structures. Minimal competitive effects were observed on the adsorption of p-chlorophenol to the copolymers in the presence of copper ions in solution. Similarly, the presence of p-chlorophenol in solution or adsorbed onto the copolymers did not interfere with copper adsorption. Replacement of a small portion of the benzene bridge in the 90:10 BENZ:EDA copolymer with diethylbenzene produced a copolymer 2.5-fold more efficient for p-chlorophenol adsorption. ICP analysis revealed that greater than 98% of adsorbed copper was removed during extraction with HCl, and this extraction process can be repeated with no difference in copper adsorption after regeneration.

The chemistry of additives in damascene copper plating

Copper plating baths used for forming integrated circuit interconnects typically contain three or four component additive mixtures which facilitate the superfilling of via holes and trench lines during damascene plating. Extensive study over the last two decades has provided researchers with an understanding of the underlying mechanisms. The role of cuprous intermediates in the copper deposition reaction has long been acknowledged, but it is not yet fully understood. In this paper we describe the results of an electrochemical study of the interaction of the organic additives used with copper and copper ions in solution. It is shown that cuprous intermediates near the copper surface affect the overpotential and the kinetics of plating. The additives regulate the presence of cuprous species on the surface; levelers and suppressors inhibit Cu <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> formation, whereas accelerating additives enhance Cu <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> formation. Acceleration by the bis(sodiumsulfopropyl) disulfide (SPS) additive results from accumulation of cuprous complexes near the surface. Adsorbed cuprous thiolate [Cu(I)(S(CH <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> ) <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> SO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> H) <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ad</inf> ] is formed through interaction of Cu <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> ions and SPS rather than Cu <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> and mercaptopropane sulfonic acid (MPS).

Selective separation of pyrite and chalcopyrite by biomodulation

Selective separation of pyrite from other associated ferrous sulphides at acidic and neutral pH has been a challenging problem. This paper discusses the utility of Acidithiobacillus ferrooxidans for the selective flotation of chalcopyrite from pyrite. Consequent to interaction with bacterial cells, pyrite remained depressed even in the presence of potassium isopropyl xanthate collector while chalcopyrite exhibited significant flotability. However, when the minerals were conditioned together, the selectivity achieved was poor due to the activation of pyrite surface by the copper ions in solution. The selectivity was improved when the sequence of conditioning with bacterial cells and collector was reversed, since the bacterial cells were able to depress collector interacted pyrite effectively, while having negligible effect on chalcopyrite. The observed behaviour is analysed and discussed in detail. The separation obtained was significant both at acidic and alkaline pH. This selectivity achieved was retained when the minerals were interacted with both bacterial cells and collector simultaneously.

Transient Adsorption of Sulfate Ions during Copper Electrodeposition

Surface-enhanced Raman scattering (SERS) spectroelectrochemical investigations have been carried out in real time on the electrodeposition of copper from sulfuric acid solutions. Sulfate spectra were observed during copper deposition, but not on a copper surface at the same potential in the absence of copper ions in solution. This indicated that sulfate adsorption is a transient process associated with metal deposition. The sulfate band was blue shifted by from its position in spectra from copper(II) sulfate or sulfuric acid solutions, and only the symmetrical stretching vibration band was observed. Chloride displaced sulfate when trace amounts of this halide were also present in solution. Nitrate ions were found to be specifically adsorbed on copper surfaces in nitric acid solutions. When copper ions were present at the interface, a nitrate stretch band, blue shifted by was also observed and this is assigned to adsorption on freshly deposited copper. SERS investigations of copper electrodes in the presence of thiourea confirmed previously reported findings. © 2004 The Electrochemical Society. All rights reserved.

Use of radiotracer in adsorption studies of copper on peat

In this work copper adsorption by peat was studied using 64Cu as tracer considering kinetic and thermodynamic aspects of the process. The study was carried out in agitated batch experiments with copper ion solutions with different initial concentrations at pH 4.5. Adsorption isotherms determined from equilibrium experiments by fitting experimental data to the Langmuir equation showed good correlations. Data obtained from kinetics experiments were fitted to a pseudo-second order model and also in this case a good correlation was obtained. Some parameters calculated from these studies such as rate constant or peat sorption capacity can be used in the development of a waste treatment process based on peat adsorption in batch or in column. The use of the 64Cu radiotracer is presented as a simple, rapid and efficient technique to assess the copper adsorption by the peat.

SEM-EDX STUDIES OF CHITOSAN DERIVATIVES-METAL ADDUCTS

Chitosan was obtained from shrimps shells (pleuroncodes monodon) using chemical methods. A series of chitosan (QS)charged with solution of copper, cobalt, nickel and mercury ions were prepared at room temperature using the batch method. N-3,5-diethylamino benzoyl chitosan (QDAB); N,O-dimercapto succinate chitosan (QNOT) and 4-aminobenzoate chitosan (QAB) derivatives were prepared. The chitosan metal adducts with Cu, Co, Ni and Hg ions and derivatives maximum loading is discussed. Chitosan and derivatives containing copper were analyzed by SEM to find out the morphology of the polymers. Chitosan-Cu and derivatives charged, QDAB-Ni and QDAB-Hg were analyzed by EDX to verify the presence of the metal in the polymeric chain

Acid recycling to optimize citric acid-modified soybean hull production

Modification of soybean hulls with citric acid (CA) improves the metal ion binding capacity of the hulls. A process for this modification has been developed. However, the process must be optimized for it to be cost effective. In this regard, the objectives of this study were (1) to develop a wash procedure to remove non-reacted or residual CA after soybean hull modification in order to maximize the amount of non-reacted acid removed, but minimize the subsequent effect on the product's ability to adsorb copper ion (Cu 2+), and (2) to determine whether recycling non-reacted acid in the modification process, along with unused acid, can produce a product with similar copper ion adsorption compared with the use of unused acid only. To meet these objectives, an effective water washing procedure was developed to remove the residual CA associated with the modified soybean hulls. This washing procedure included removal of non-reacted acid, evaporation of excess water to the original volume of acid solution used, and addition of unused CA to reconstitute the solution to its original molarity. Reconstituted CA solutions prepared in this manner were used through three cycles of soybean hull modification. The effectiveness of the reconstituted CA to modify soybean hulls after each cycle was measured by the modified hulls ability to bind copper ions in solution. After three reaction cycles, there was a 7% reduction in copper ion adsorption. In general, two water wash cycles were necessary to remove sufficient non-reacted CA so that metal ion binding of the hulls was not affected, and the use of residual CA to modify soybean hulls can be successfully accomplished with only a small reduction in copper ion binding.

Development of fluorescent film sensors for the detection of divalent copper.

Monolayers of several peptide lipids at air-water and air-solid interfaces were prepared using Langmuir and Langmuir-Blodgett (LB) film techniques, and tested as fluorescent sensors for copper ions in aqueous phase. In one method, both the ionophore and the fluorophore were in the same molecule (lipid A), so intramolecular interaction was responsible for the fluorescence quenching of monolayers of this lipid. In the other method, ionophore and fluorophore were located on two different molecules (lipids B and C) so the intramolecular coupling does not exist; instead the fluorescence quenching was realized by a through-space interaction mechanism. Several experimental techniques, including pi-A isotherm, epifluorescence microscopy, and absorption and emission spectroscopies were used to study the different characteristics of copper ion effect on the properties of the lipid monolayers. Additionally, the fluorescence quenching properties of the Langmuir monolayers were found to be transferred to the one-layer LB films. On LB films, the fluorescence response presented a clear selectivity for copper ions in comparison with several other transition metal ions. Further, an excellent reversibility was observed: the fluorescence was switched OFF by immersing the solid substrate in copper ion solution and ON by washing with HCl solution. The intermolecular approach used here seems to be a very flexible and general method to design surface-oriented fluorescent sensors to meet different analytic purposes.

Adsorption of Copper, Zinc and Nickel Ions from Single and Binary Metal Ion Mixtures on to Chicken Feathers

Certain industries often produce mixtures of heavy metal ions in their waste products. Because of the nature of heavy metal ions and the adsorption process, such metal ions can compete with each other for the sorption sites on an adsorbent during adsorption processes. In the present work, binary systems composed of copper, zinc and nickel ions were selected as examples of heavy metal ion mixtures and tested via batch adsorption processes using chicken feathers as an adsorbent. The uptake of individual metal ions was depressed by the presence of another. Thus, the uptake of copper ions from an initial copper ion solution of 20 ppm concentration was reduced from 0.042 mmol/g to ca. 0.019 mmol/g by the presence of a similar concentration of nickel ions. The Freundlich, Langmuir and Sips multi-component adsorption models were employed to predict the uptake of metal ions from binary metal ion solutions using constants obtained from adsorption isotherm models applied to single-solute systems.