Cu2+, Fe2+ and Fe3+ analysis of bioleaching solutions using chronoamperometry and BDD electrode

In this work, a boron-doped diamond (BDD) electrode was evaluated for the electroanalytical determination of millimolar concentrations of Cu²⁺, Fe²⁺ and Fe³⁺ using chronoamperometry. The interfering role that each ion plays on the quantitative determination of other metal ion concentrations was also assessed. No interference from other metal ions was observed when Fe³⁺ and Fe²⁺ were analysed. By contrast, reduction of Fe³⁺ took place at the same potential where [Cu²⁺] was measured causing a minor interference to the Cu²⁺ signal. A multiple linear regression (MLR) calibration model was made for each analyte using real bioleaching samples, which demonstrated high coefficients of determination and adequate standard errors. The methods developed were used to monitor bioleaching of chalcopyrite for 4 months. The electroanalytical methods are particularly well-suited for analysing Cu²⁺, Fe³⁺ and Fe²⁺ concentration in acidic mine drainage (AMD) and bioleaching environments.     

Influence of the Metal Ions Cr3+, Fe3+, Ni2+ and Cu2+ on the Stability and Oxygen Consumption of Acrylic and Methacrylic Acid

For the safe and trouble‐free operation of a manufacturing plant and the safe storage of acrylic, as well as methacrylic monomers, it is important to know the polymerization stability as a function of the process parameters (temperature, oxygen concentration, and impurities, e.g., metal ions). Contamination with metal ions can be caused by the corrosion of steel units. Therefore, the influence of the metal ions Cr³⁺, Fe³⁺, Ni²⁺ and Cu²⁺ in the concentration range of 0–10 ppm (g g^–1) on the polymerization behavior and the oxygen consumption of acrylic and methacrylic acid were examined in this work. It was shown that Cr³⁺, Ni²⁺, and Cu²⁺ ions extend the inhibition period of acrylic acid (AA) and methacrylic acid (MAA) and reduce the O₂ consumption. Fe³⁺ ions, however, cause a decrease of the inhibition period and in the case of AA an increase of the O₂ consumption, which leads, in the end, to a faster unintentional polymerization. Therefore, alloys which contain iron should be avoided as far as possible in the construction of AA plants. Fe³⁺‐ions show the opposite influence towards MAA, here the presence of Fe³⁺ shows a stabilizing effect.     

Effect of Co2+, Ni2+, Cu2+, or Zn2+ on properties of polyaniline nanoparticles

Uniform polyaniline (PANI) nanoparticles with typical sizes of about 50 nm were electropolymerized on indium tin oxide surfaces in the presence of Co²⁺, Ni²⁺, Cu²⁺, or Zn²⁺. According to shaping theory, we first suggest the reason forming PANI spherical particles. Their conductivity, UV‐vis spectra, FTIR spectra, X‐ray diffraction, and thermogravimetric analysis were investigated. The conductivities and crystallinity of PANI doped with these ions are higher than those of PANI doped with HCl (PANI/HCl). Both UV‐vis absorption spectra and FTIR spectra indicate the interactions between Co²⁺, Ni²⁺, Cu²⁺, or Zn²⁺ and PANI chains. TG analysis also shows that the thermal stability of PANI doped by Co²⁺, Ni²⁺, Cu²⁺, or Zn²⁺ is lower than that of PANI/HCl. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Concentration and separation of aqueous solutions of Cu2+, Ni2+, Fe3+ by dextran

The effects of water-soluble polymers on the concentration and separation of the aqueous solutions of the metal ions have been studied. The separation of metal ions can be possible by ultrafiltration-complexation process. The effect of Dextran, which is a water-soluble polymer, on the concentration and separation of metal ions (Cu²⁺, Ni²⁺, Fe³⁺) have been investigated by using EC-PEG 4000 alloy membranes. The permeability of these membranes for metal ions has been rrecorded at constant pressure but different pH values. It has been notices that the highest water-permeable membrane is also permeable towards Cu²⁺ and Ni²⁺, but has shown a considerable retention for Fe³⁺ as a result of the hydrolysis of Fe³⁺. The retentions of metallic ions and metallic-ion-Dextran couples have been determined at constant pressure but different pH and polymer concentration values. It has been shown that Fe³⁺/Ni²⁺ and Fe³⁺/Cu²⁺ couples can be separated by using Dextran. © 1995 John Wiley & Sons, Inc.     

Modification of chitosan with cellulose and gelatin for the removal of Cu2+, Fe2+, and Pb2+ from oily wastewater

In this study, chitosan was modified with cellulose and gelatin for the removal of Cu²⁺, Fe²⁺, and Pb²⁺ from oily wastewater. Chitosan was characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Carbon (77.54%), hydrogen (10.30%), oxygen (8.89%), nitrogen (2.74%), and sulphur (0.53%) were found in the organic constitution of the oil utilized, according to elemental analysis. Despite the presence of other metal ions in the used oil and effluent, this study focused solely on Cu²⁺, Fe²⁺, and Pb²⁺. Studies on the removal of Cu²⁺, Fe²⁺, and Pb²⁺ from oily wastewater were conducted, and multiple effect factors such as temperature and pH, time and pH, solvent and pH, temperature and time, temperature and solvent, and time and solvent were evaluated. An adsorption study was performed to remove the heavy metals. The results revealed that the highest percentage removal of Cu²⁺ was 96.62 (pH = 7.52 and conductivity = −12 mV), of Fe²⁺ was 97.95 (pH = 6.30 and conductivity = +68 mV), and of Pb²⁺ was 98.86 (pH = 10.58 and conductivity = −170 mV). To analyze the impacts of experimental factors, experiments were developed using central composite design (CCD) based on response surface methodology (RSM).     

Adsorption of Pb2+, Cu2+ and Co2+ by polypropylene fabric and polyethylene hollow fiber modified by radiation-induced graft copolymerization

Cation-exchange adsorbents were prepared by radiation-induced grafting of glycidyl methacrylate (GMA) onto polypropylene (PP) fabric and polyethylene (PE) hollow fiber and subsequent phosphonation of epoxy groups of poly(GMA) graft chains. The adsorption characteristics of Pb²⁺, Cu²⁺ and Co²⁺ for the two cation-exchange adsorbents were studied. In the grafting of GMA onto PP fabric, the degree of grafting (%) increased with an increase in reaction time, reaction temperature, and pre-irradiation dose. The maximum grafting yield was observed around 60% GMA concentration. In 50, 130 and 250% GMA-grafted PP fabric, the content of phosphoric acid was 1.52, 3.40 and 4.50 mmol/g at 80 °C in the 85 % phosphoric acid aqueous solution for 24 h, respectively. The adsorption of Pb²⁺, Cu²⁺ and Co²⁺ by PP fabric adsorbent was enhanced with an increased phosphoric acid content The order of adsorption capacity of the PP fabric adsorbent was Pb²⁺>Co²⁺>Cu²⁺. In adsorption of Pb²⁺, Cu²⁺ and Co²⁺ by PE hollow fiber, the amount of Pb²⁺ adsorbed by the PE hollow fiber adsorbent containing 1.21 mmol/g of -PO₃H wasca. 54.4 g per kg. The adsorption amount of Cu²⁺ and Co²⁺ in the same PE hollow fiber wasca. 21.0 g per kg andca. 32.1 g per kg, respectively. The order of adsorption of the PE hollow fiber adsorbent was Pb²⁺>Co²⁺>Cu²⁺.     

Synthesis of a highly selective bis-rhodamine chemosensor for naked-eye detection of Cu2+ ions and its application in bio-imaging

A bis-rhodamine based fluorescent chemosensor for naked-eye detection of Cu²⁺ with enhanced sensitivity as compared to mono-rhodamine derivative has been synthesized, and its selectivity for Cu²⁺ in the presence of other competitive metal ions (Li⁺, Na⁺, K⁺, Cs⁺, Mg²⁺, Ca²⁺, Sr²⁺, Cr³⁺, Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺, Zn²⁺, Cd²⁺, Hg²⁺, and Pb²⁺), and application in bio-imaging are demonstrated.     

SORPTION PROCESSES OF NATURAL IRANIAN BENTONITE EXCHANGED WITH CD2+, CU2+, NI2+, AND PB2+ CATIONS

Experimental studies on the retention of cadmium (Cd²⁺), copper (Cu²⁺), nickel (Ni²⁺), and lead (Pb²⁺) by bentonite samples from Iran were conducted using single- and multiple-component solutions. Based on the sorption capacity of bentonite the following order was obtained for single- and multiple-component solutions: Pb²⁺ > Cd²⁺ > Ni²⁺ > Cu²⁺. The maximum adsorption capacities of bentonite with metals in single- and multiple-component solutions were 29.5%, 22.5%, 19.2%, and 17.1% and 13.5%, 13.4%, 12.1%, and 9.1% for Pb²⁺, Cd²⁺, Ni²⁺, and Cu²⁺, respectively. Desorption isotherms of Cd²⁺, Cu²⁺, Ni²⁺, and Pb²⁺ deviated significantly from the sorption isotherms, thereby indicating irreversible or very slowly reversible sorption. Finally, soil solution saturation indices and metal speciation were assessed using the Visual MINTEQ 2.6 program and the probability of mineral precipitation was supported by scanning electron microscopy.     

Thin-Layer Chromatography of Metal Ions in Formic Acid Medium on Impregnated and Unimpregnated Silica Gel G: Semiquantitative Determination of Fe3+, Cd2+, Th4+, Al3+, Zn2+, UO2+ 2, VO2+, Ce4+, and Ni2+

Abstract

The adsorption behavior of metal ions in the formic acid-sodium formate system using unimpregnated as well as impregnated silica gel G as thin layers has been studied. A remarkable result of this study is the dramatic selectivity of impregnated silica gel G thin layers when compared to the corresponding unimpregnated silica gel G thin layers. This impregnation effect provides us with a new adsorbent phase which is sufficiently stable in the formic acid-sodium formate medium. Some important ternary separations have been achieved on silica gel G thin layers. Al³⁺, Ni²⁺, Fe³⁺, and Pb²⁺ have been qualitatively separated from mixtures of other ions. Cu²⁺ has been selectively separated on impregnated silica gel G thin layers. The semi-quantitative determination of nine metal ions on impregnated silica gel G layers has also been attempted.     

Selective Extraction of Cu2+ and Ag+ Ions from Sulfuric Acid by Synergistic Combinations of Tetradentate Thia Macrocycles with Dioodecylnaphthalene Sulfonic Acid

Abstract

The aqueous-insoluble thia macrocycles tetrathia-14-crown-4 (TT14C4) and tetrathia-16-crown-4 (TT16C4) strongly and selectively synergize the extraction of Cu²⁺ and Ag⁺ ions from aqueous sulfuric acid solutions by the organophilic cation exchanger didodecylnaphthalene sulfonlc acid (HDDNS) in toluene diluent. Over a range of sulfuric acid concentrations, the selectivity is given by the order Ag² > Cu²⁺ > Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺, and Zn²⁺, where synergism occurs only for Ag⁺ and Cu²⁺. Selectivity factors greater than 300 have been achieved for Cu²⁺ over ubiquitous Fe³⁺. The synergistic extraction of Cu²⁺ and Ag⁺ was explored as a function of sulfuric acid concentration, relative concentration of macrocycle vs. HDDNS, and loading.     

Effect of Mg2+, Li+, Na+ and K+ on the Electrocrystallization of Nickel from Aqueous Sulfate solutions containing Boric Acid

The effects of metal ions such as Mg²⁺, Li⁺, Na⁺ and K⁺ on the cathodic current efficiency, deposit morphology, crystallographic orientation and polarization behaviour during nickel deposition on stainless steel from aqueous sulfate solutions containing boric acid were investigated. There was virtually no change in current efficiency in presence of these metal ions, but changes were observed in the deposit morphologies and crystal orientations even though all the deposits looked bright, smooth and coherent. Changes were also observed in the polarization behaviour during nickel electrocrystallization in presence and absence of boric acid. An attempt has been made to correlate the effect of these metal ions on various parameters studied.     

Cu2+ Selective Chromogenic Behavior of Calix[4]arene Derivative

This study involves the copper selective chromogenic response of 5, 11, 17, 23-Tetrakis (N-pyrrolidinomethyl)-25, 26, 27, 28-tetrahydroxycalix[4]arene based mannich base (3). Complexation ability of (3) was explored by examining the effect of a series of various metal ions, such as Li⁺, Na⁺, K⁺, Ag⁺, Ba²⁺, Ca²⁺, Mn²⁺, Mg²⁺, Sr²⁺, Ni²⁺, Cd²⁺, Co²⁺, Cu²⁺, Hg²⁺, Pb²⁺, Zn²⁺, Fe²⁺, Fe³⁺, and Al³⁺, by using UV-visible spectroscopy. Ligand (3) exhibited pronounced selectivity toward Cu²⁺ even in the presence of various co-existing ions. The stoichiometric analysis, i.e., Job's plot revealed that (3) form 1:1 complex with Cu²⁺ ion in DMF-H₂O system. The complexation phenomenon was confirmed by FT-IR spectroscopy that favors the selective nature of (3) with Cu²⁺.     

UV-LEDs assisted peroxymonosulfate/Fe<Superscript>2+</Superscript> for oxidative removal of carmoisine: The effect of chloride ion

The performance of UVA-LEDs assisted peroxymonosulfate (PMS)/Fe²⁺ system was evaluated on carmoisine (E122) decolorization. Complete color removal was obtained under the conditions of pH=3.0, PMS=1.5 mM, Fe²⁺=1 mM and 25 min reaction time. UVA-LEDs were preferable compared to conventional UVA lamp in terms of decolorization. The functions of Co²⁺, Cu²⁺, Mn²⁺ and Fe²⁺ were compared and their results showed that Co²⁺ and Fe²⁺ had the highest efficiencies. Moreover, the presence of chloride ion showed a double role in different concentrations in which promotional effect was observed in 100 mM Cl^?<, while inhibitory effect occurred in 1–10 mM Cl^?. However, the high concentration of chloride had no influence on mineralization of E122. The scavenging results demonstrated that the UV irradiation increased the contribution of HO^?. In addition, in the presence of chloride ion, HOCl along with sulfate and hydroxyl radicals were the major oxidative agents.     

Effect of Transition-Metal Ion Doping on Electrocatalytic Activities of graphene/polyaniline-M2+ (Mn2+, Co2+, Ni2+, and Cu2+) Composite Materials as Pt-Free Counter Electrode in Dye-Sensitized Solar Cells

A series of graphene/polyaniline-M²⁺ (M²⁺ = Mn²⁺, Co²⁺, Ni^2+, and Cu²⁺) composite counter electrodes were synthesized by doping transition-metal ions in polyaniline and graphene for dye-sensitized solar cells (DSSCs). The counter electrodes showed significantly high photoelectric conversion efficiency of 5.38% (Mn²⁺), 4.65% (Co²⁺), 4.00% (Ni²⁺), and 2.49% (Cu²⁺). The catalytic activities of graphene/polyaniline-M²⁺ electrodes were evaluated using cyclic voltammetry, Nyquist plots, and Tafel polarization. The chemical characteristics and surface morphology of graphene/polyaniline-M²⁺ composite materials were determined by infrared spectroscopy and scanning electron microscopy. These results indicate a potential application of ion-doped polyaniline as the counter electrode in cost-effective DSSCs.     

Synthesis and photophysical properties of a novel green fluorescent polymer for Fe3+ sensing

BACKGROUND: In recent years, environmental pollution has become a major concern for industrial societies. The design of highly selective and sensitive sensor materials has become a very important scientific goal. RESULTS: A novel 4‐amino‐substituted 1,8‐naphthalimide dye with intense green fluorescence was synthesized. The dye was then copolymerized with methyl methacrylate. The presence of metal cations (Ca²⁺, Mg²⁺, Cr³⁺, Mn²⁺, Fe³⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺) could quench the fluorescence intensity of a tetrahydrofuran solution of the dye and the copolymer at different levels. The effect of Fe³⁺ was much stronger than that of the other cations. There was a good linear correlation between F₀/F (F₀ and F are the fluorescence intensities in the absence and presence of the metal ions, respectively) and the Fe³⁺ concentration in the range 1.33 × 10^?7–4.00 × 10^?4 mol L^?1. The polymeric sensor in a film state exhibited a dynamic response to Fe³⁺ in the concentration range from 3.44 × 10^?6 to 3.04 × 10^?3 mol L^?1 and the average response time was about 20 s. CONCLUSION: In view of the selectivity and rapid responsivity of the polymer sensor studied, it could be used as a new polymeric sensor for water pollution by Fe³⁺ cations. Copyright © 2008 Society of Chemical Industry     

Catalytic Mechanism of Cu2+ and Fe3+ in Alkaline O2 Oxidation of Lignin

The catalytic mechanisms of Cu²⁺ and Fe³⁺ in the alkaline oxidation of lignin are discussed. Best aldehyde yields were obtained by using Cu²⁺ and Fe³⁺ as catalysts. Without these two ions present or in the absence of one or other of them, yields were lower. It is clear that Cu²⁺ and Fe³⁺ significantly influence the reactions. Cu²⁺, acting as the electron acceptor, accelerates the formation of the phenoxy radical, thus speeding up the radical reaction. In order to interpret the effect of Fe³⁺ on oxidative degradation of lignin and formation of aldehydes, formation of an intermediate, O₂-Fe³⁺-lignin complex and its catalytic mechanism have been proposed.     

Synthesis of Copper and Lead Ion Imprinted Polymer Submicron Spheres to Remove Cu2+ and Pb2+

In this paper, Methacrylic acid (MAA) and 4-vinyl pyridine (4-VP) as functional monomers, Ethylene glycol two methyl acrylate (EGDMA) as crosslinking agent, isopropyl alcohol as the solvent, prepared the Cu(II)- and Pb(II)- imprinted polymers (IIPs) submicron spheres by precipitation polymerization. The presence/absence of the template ion in the preparation of the imprinted polymer was confirmed by EDX spectroscopy, and the structure of the particles was investigated using IR, SEM and BET analysis. From different components of crosslinker/monomer (C/M) ratio analysis, C/M at 1:3 was the optimal ratio for preparing IIPs. Atomic absorption spectroscopy (AAS) was characterized the imprinted polymers absorption behavior. The results show that the maximum adsorption capacity of Cu²⁺ and Pb²⁺ -imprinted polymer were 26.9 mg g^?1 and 25.3 mg g^?1, respectively. They also have good adsorption capacity and superior selectivity property for Cu²⁺ and Pb²⁺ in water, respectively. The selectivity factors (α) for Ni²⁺, Zn²⁺, Co²⁺ and Fe²⁺ were 16.5 (Cu²⁺) and 12.1 (Pb²⁺), 13.8 (Cu²⁺) and 16.2 (Pb²⁺), 10.8 (Cu²⁺) and 10.1 (Pb²⁺), 20.4 (Cu²⁺) and 20.7 (Pb²⁺), respectively. The regeneration experiment result demonstrates an excellent re-utilization property of these two type IIPs, after ten uses, the adsorption capacity can maintain above 60%.

     

Charge reduction and regeneration in K+, Na+, Mg2+, Ni2+ and Co2+-exchanged Wyoming Bentonite

Controlled calcination of ion-exchanged Wyoming Bentonite in the presence and absence of ammonia leads to layer charge reductions. Detailed chemical analyses of both unexchangeable and exchangeable species lead to the conclusion that in no case is there migration of the original interlamellar cations into the octahedral region of the layers although, in terms of ionic radius alone, Mg²⁺, Ni²⁺ and, possibly Co²⁺, might be expected to do so. The production of unexchangeable Mg, Ni or Co, is identified as resulting from high temperature hydrolysis leading to hydroxide or oxide formation.     

The effect of Fe on magnetic moment of electrodeposited CoFe alloys—Experimental study and analytical model

The effect of Fe³⁺ concentration on saturation magnetic flux density (B_s) of electrodeposited Co_40-44Fe_60-56 films was investigated. The results show that if the conditions at the electrochemical interface for nucleation/precipitation of iron(III) hydroxide (Fe(OH)₃) are reached, the B_s of electrodeposited Co_40-44Fe_60-56 films quickly decreases as a result of the Fe(OH)₃ incorporation into deposit. These conditions are discussed as a function of the solution formulation (pH) and the parameters of electrodeposition process (current density, current efficiency, diffusion layer thickness) and a simple analytical model is developed qualitatively describing the hydroxide incorporation phenomenon and resulting decrease in B_s of Co_40-44Fe_60-56 films.     

Effects of metallic and D2EHPA impurities on nickel electrowinning from aqueous sulphate baths

The presence of metallic and organic solvent impurities in pregnant electrolyte during hydrometallurgical processing causes problems in nickel electrowinning. To overcome these problems, a study on the combined effects of metallic and D2EHPA impurities, on nickel electrodeposition has been carried out. The effects of such impurities on deposit physical appearance, current efficiency, deposit contamination, crystallographic orientation and deposit morphology are discussed. Based on the experimental data and observations, it is possible to achieve smooth and perfect nickel sheet with reasonable current efficiency and purity from the contaminated leach liquors of nickel bearing raw materials being processed in the Regional Research Laboratory, Bhubaneswar. Moreover, the economy of the nickel electrowinning process can be improved by careful selection of experimental conditions.