Preparation of compact copper from slurries formed in etching of printed-circuit boards

Technological solutions for copper recovery in the form of a compact metal from a slurry formed in etching of printed-circuit boards as a starting material were developed.     

Use of precipitate electroflotation for increasing the degree of wastewater treatment to remove nonferrous metals

A method is suggested and studied of removing nonferrous metals of from waste waters. The method is, that waste water containing nonferrous metals is treated to adjust pH to 9–10, after which sodium orthophosphate solution is added at metal/phosphate ion weight ratio 1 : (0.5–0.7) resulting in formation of slightly water-soluble metal hydroxyphosphate whose solubility is inferior to that of corresponding metal hydroxide. To isolate resulting compounds, electroflotation method with insoluble anodes is employed. Efficiency of removing nonferrous and heavy metals meets norms established for water discharge into fish-industry reservoirs.     

The effect of surfactants and complexing agents on the fluorimetric determination of uranium

Summary The effect of surfactants, condensed phosphates, soap, EDTA, NTA, citric acid, oil and Alamine-336 on the fluorimetric determination of uranium in a 5-ml aqueous sample extracted with methyl isobutyl ketone after addition of saturated calcium nitrate or 1N acid-deficient saturated aluminium nitrate salting-out solutions has been established. The error produced by these compounds, even at concentrations up to 500 mg/l, does not exceed ±10%, except for anionic LAS-type detergent, which at above the 50 mg/l level forms stable emulsions after extraction from solutions containing the acid-deficient aluminium nitrate salting-out reagent. Up to 1 hour of standing time after extraction may be required for the emulsions to break. The detection limit for uranium is 1.1g/l (2s).

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Zusammenfassung Die Wirkung von Schaummitteln, Polyphosphaten, Seifen, ÄDTA, NTA, Zitronensäure, Öl und Alamin-336 bei der fluorimetrischen Uranbestimmung in einer wäßrigen 5-ml-Probe nach Extraktion mit Methylisobutylketon aus einer mit gesättigtem Calciumnitrat oder säurefreier gesättigter Aluminiumnitratlösung zwecks Aussalzung versetzten Lösung wurde beschrieben. Der durch diese Verbindungen verursachte Fehler übersteigt auch bei Konzentrationen bis zu 500 mg/l nicht ±10%, mit Ausnahme anionischer Detergentien vom LAS-Typ (lineare Alkylsulfonate), die oberhalb 50 mg/l nach Extraktion aus Lösungen, die säurefreies, gesättigtes Aluminiumnitrat enthalten, stabile Emulsionen bilden. Um diese zu beseitigen, muß man nach der Extraktion 1 Stunde stehen lassen. Die Nachweisgrenze für Uran beträgt 1,1gmg/l (2s).

     

On purification of wastewater containing complex aluminum and silicon fluorides to remove fluorine

Possibility of sorption-precipitation purification of wastewater to remove admixtures of fluorine with titanium compounds was studied.     

Ion-interaction chromatographic separation of metal cations in the presence of complexing agents

The mechanism of the separation of selected divalent metal cations (Zn²⁺, Ni²⁺, Co²⁺, Cd²⁺, Mn²⁺, Fe²⁺ and Pb²⁺) by ion-interaction chromatography (IIC) in the presence of complexing agents has been investigated; the dependence of the retention of the analyte on the concentration of the complexing ligand has been studied. Separations have been obtained on an octadecyl-bonded silica column, mobile phases containing an ion-interaction agent (octane sulfonate), eluting cations (Na⁺ ions) and a complexing ligand (oxalate anions).     

Extraction separation of rare-earth elements by amines in the presence of complexing agents

The extraction separation of La and Sm by benzyldibutylamine (BDBA) from an aqueous solution containing 6 mol·dm^–3 NaNO₃ and 0.5 mol·dm^–3 HNO₃ is not very efficient. It may remarkably be improved by addition of a complexing agent, 2-hydroxyethylethylenediaminetriacetic acid (HEDTA). The effect of preferential La extraction into the organic phase together with the effect of preferential complexation of Sm in the aqueous phase may lead, by proper choice of the complexing agent concentration, to a 7–10 fold increase in _La/Sm values. The procedure described here enables fairly good separation of a major from minor elements.     

The effect of surfactants,cations and complexing agents on the spectrophotometric determination of microgram amounts of uranium in waters

Summary Cationic, anionic and non-ionic detergents, phosphate, soap, citric acid, Alamine-336 and mineral oil at concentrations of 100 mg/l do not interfere in the bromo-PADAP method for uranium. Iron(III), nickel(II), copper(II), chromium(III) and vanadium(V) give additive errors, but do not interfere when present at the concentrations usual in waters. Vanadium(V) interference can be minimized by reducing vanadium(V) to (IV). Sodium tripolyphosphate (100 mg/l) and sodium pyrophosphate (20 mg/l) interfere badly, but the addition of 2 mg of thorium restores recovery to 97–98%. NTA and EDTA interfere slightly, giving recoveries of 96–97%. Provided that the water is not grossly contaminated by metals, uranium can be determined in fresh water at concentrations of 20g/l and in saline waters at 60g/l.

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Die Wirkung von Schaummitteln, Kationen und Komplexbildnern auf die spektrophotometrische Bestimmung von Mikrogrammengen Uran in Wässern

Zusammenfassung Kationische, anionische und nicht-ionisierbare Detergentien, Phosphate, Seifen, Zitronensäure, Alamin-336 und Mineralöl in Mengen von 100 mg/1 stören die Uranbestimmung mit 2-(5-Bromo-2-pyridylazo)-5-diäthylamino- phenol (Brom-PADAP) nicht. Eisen(III), Nickel(II), Kupfer(II), Chrom(III) und Vanadin(V) verursachen additive Fehler, stören aber in Konzentrationen, wie sie üblicherweise in Wässern auftreten, nicht. Die Störung durch Vanadin(V) kann durch dessen Reduktion zur 4wertigen Form minimalisiert werden. Natriumtripolyphosphat (100 mg/l) und Natriumpyrophosphat (20 mg/l) stören stark, aber der Zusatz von 2 mg Thorium gewährleistet Ergebnisse von 97–98%. NTA und ÄDTA stören geringfügig und führen zu Resultaten von 96–97%. Vorausgesetzt, das Wasser ist nicht sehr stark durch Metalle verunreinigt, läßt sich Uran in frischen Wasserproben in Mengen von 20 mg/l, in Salinenwässern in Mengen von 60 mg/l bestimmen.

     

Effect of complexing agents and surfactants on the sorption of Co(II) by kaolinite

The effect of pH on the removal of Co(II) by kaolinite both in the absence and presence of phosphate, citrate, oxalate and EDTA anions, and cationic and anionic surfactants have been investigated and the results obtained are compared with the precipitate formation curve of Co(II) calculated theoretically from published hydrolysis data of the metal ion. In general, the results indicate that the percent adsoprtion of Co(II) increases with the pH and that kaolinite has little affinity for anionic metal complexes. Both strong cationic and anionic surfactants decrease the percent removal of Co(II) by kaolinite but the reasons are different. On the other hand, the weakly ionized anionic surfactant, potassium stearate, enhances the adsorption of Co(II) by kaolinite. The results are discussed in terms of the hydrolysis of Co(II), the properties of kaolinite, and the possible interaction between the ligands tested and both Co(II) and the clay mineral.     

Sono-electroanalysis of copper: enhanced detection and determination in the presence of surfactants

Surfactant adsorption has been shown to have a passivating effect on the electrode surface during anodic stripping voltammetric measurements. In the present work the feasibility of sono-anodic stripping analysis for the determination of copper in aqueous media contaminated with surfactant has been studied at an unmodified bare glassy carbon electrode. We illustrate the deleterious effect of three common surfactants, sodium dodecyl sulfate (SDS), dodecyl pyridinium chloride (DPC) and Triton-X 100 (TX-100) on conventional electroanalysis. The analogous sono-electroanalytical response was investigated for each surfactant at ultrasound intensities above and below the cavitation threshold. The enhancement in the stripping signal observed is attributed to the increased mass transport due to acoustic streaming and above the cavitation threshold the intensity of cavitational events is significantly increased leading to shearing of adsorbed surfactant molecules from the surface. As a result accurate analyses for SDS concentrations up to 100 ppm are possible, with analytical signals visible in solutions of SDS and TX-100 of 1000 ppm. Analysis is reported in high concentration of surfactant with use of sono-solvent double extraction. The power of this technique is clearly illustrated by the ability to obtain accurate measurements of copper concentration from starting solutions containing 1000 ppm SDS or TX-100. This was also exemplified by analysis of the low concentration 0.3 microM Cu(II) solution giving a percentage recovery of 94% in the presence of 1000 ppm SDS or TX-100.     

Voltammetric Behaviour of Nickel in the presence of cobalt and zinc ions and surfactants

The reduction of the nickel dimethyldioxime complex at mercury electrodes is investigated in the presence of electrochemically interfering ions (Co²⁺, Zn²⁺). In addition the influence of various surfactants on the reduction process was studied by differential pulse adsorptive stripping voltammetry. An improvement of the selectivity without a loss of sensitivity was achieved for the trace determination of nickel in the presence of cobalt by the use of an in-situ modification of the mercury electrode with adsorbed tetrabutylammonium. It is shown that a 10⁶-fold excess of zinc does not distrub the nickel signal in the presence of a sufficient amount of ammonia in the supporting electrolyte.     

The influence of complexing agents on the effectiveness of electrochemical masking with anionic surfactants in anodic stripping voltammetry

The influence of sodium dodecyl sulphate, sodium dodecyl sulphonate and sodium stearinate on the anodic stripping peaks of Tl(I), Pb(II), Cd(II), Cu(II) and In(III) was investigated. The supporting electrolytes were 0.5M sodium sulphate solution, 0.2M citrate solution (pH 3.7, 4.6 and 7.3), 0.5M tartrate solution (pH 4.4) and 0.1M solution of EDTA (pH 4.4). The composition of complex compounds forming in a solution under experimental conditions was defined. The conditions of ion reduction of metals on hanging mercury electrode during the electrolytical deposition were investigated. The investigation included an analysis of voltammetric curves of the metal ions. The obtained results suggest that "electrochemical masking" is much stronger in electrolytes containing a complexing agent than in the sodium sulphate solution. The influence of the complexing agent may not be explained in terms of the interaction between the form of the complex and the charge of the adsorbed surfactant particles; rather the complexing process is connected with indirect inhibition, i.e., by decreasing the rate of charge transfer reaction.     

Decay kinetics of aryloxy and semiquinone radicals in the presence of copper ions

The decay kinetics of aryloxy and semiquinone radicals in the presence of copper ions in aqueous solutions has been studied by means of the flash photolysis technique. The radicals are involved in electron transfer reactions and those leading to the formation of intermediate complexes with copper ions. The complexes of p-benzosemiquinone anion radicals and 2-hydroxyphenoxy radicals with cupric ions decay in bimolecular self-reactions at a much slower rate than the original radicals. The increased stability of the complexes compared with the initial radicals is attributed to partial delocalization of the unpaired electron over the electron shell of copper and to steric hindrances in the self-reactions of complexes.     

Computer calculation of equilibrium constants of species present in mixtures of metal ions and complexing agents

A general computer program is described for the interpretation of pH titration data for mixtures containing the ions of up to two metals and up to two ligands. The program, which employs the non-linear least-squares method, may be used to calculate equilibrium constants for hydrolysed metal ions, protonated ligands, and simple, protonated, hydrolysed, polynuclear, and mixed complexes.     

Effect of foreign ions for the determination of metal ion in the presence of surfactants

Aluminum is the third most abundant metal in the Earth’s crust. Despite its ubiquitous nature it is present in small amount in living organisms. Aluminum toxicity has been implicated in the pathogenesis of renal distinct clinical syndromes, including progressive and fatal encephalopathy and bone diseases. In the present study, Al was selected for the analysis by complexometric method. This method was based on the formation of a red colored ternary complex by the reaction of Aluminum with Aluminon (Aurin tricarboxylic acid triammonium salt) in the presence of micellar medium. The ternary complex of Aluminum with the surfactant Triton X-100 shows a maximum absorbance at 530 nm wavelength at pH 4.0 while with the sodium dodecyl sulfate it shows a maximum absorbance at 525 nm and at pH 5.0. The reaction was proceeded by the variation in pH and concentrations of surfactants, aluminon, aluminum. Their effects on the reaction of aluminum with aluminon complex in micellar media were recorded by UV-visible spectrophotometer. The reaction was found to be extremely rapid at room temperature. The system obeys Lambert Beer’s law between 0.24 and 21.74 μg/mL concentrations with Triton X-100. The values of slope, intercept and correlation coefficients were 0.07, 0.348 and 0.989, respectively. The concentration varied between 0.24 and 24.14 μg/mL with sodium dodecyl sulfate and the values of slope, intercept and correlation coefficients were 0.029, 0.148 and 0.962, respectively. The foreign ion effect was also tested by keeping the constant concentration of metal ion and determining its concentration in the presence of different foreign ions. The method was also applied for the determination of Al(III) in pharmaceutical formulations and water samples, which showed an excellent resemblance between reported and obtained results.     

Spectrofluorimetric determination of irinotecan in the presence of oxidant agents and metal ions

In this work four spectrofluorimetric methods for the determination of irinotecan (CPT-11) in human urine and pharmaceuticals have been developed. Initially, the fluorescent characteristics of irinotecan (CPT-11) have been studied in both acidic and basic media. Later, the fluorescence emission generated by the oxidation of CPT-11 with several agents was studied. A quenching of fluorescence could be observed in the presence of Ce(IV) and I₂/I⁻. Also, the reaction between several divalent and trivalent metal ions with CPT-11 was studied, and one method in presence of Fe³⁺ was developed since it was the only metal ion that changes the fluorescence of the analyte. The proposed methods present limit of detection comprises between 0.46 and 2.57 ng mL⁻¹. The spectrofluorimetric methods were applied to human urine. No pre-treatment of the sample was necessary, only a dilution 1:20 with water was made. No interference of the matrix was observed in the conditions used. Recoveries were comprises between 100.0 and 104.3%. Also, pharmaceuticals preparations were analyzed with recoveries between 106.7 and 119.7%. The proposed spectrofluorimetric methods were validated by RP-HPLC, obtaining that the oxidation with iodine is the best method to analyze urine samples, while than, the fluorimetric method developed at acidic pH value is the best for the analysis of pharmaceuticals.     

Ion-exchange separation of metal cations on a dodecylsulphate-coated C 18 column in the presence of complexing agents

Summary The mechanism of the separation of selected transition and heavy metals on a C 18 column permanently coated with sodium dodecylsulphate (SDS) in the presence of complexing agents (tartrate and oxalate anions) was investigated. The effect of the ligand concentration and of the mobile phase pH on the retention of analytes was studied in the first place. Relations were established between the capacity factor of the analytes and the ligand concentration in the mobile phase on the assumption that the retention is governed by an ion-exchange mechanism. It was found that in most cases the reciprocal value of the capacity factor is a linear function of the ligand concentration (at constant concentration of the eluting cation), which is consistent with the derived relations.     

Electrode potential-controlled DNA damage in the presence of copper ions and their complexes.

Supercoiled (sc) DNA immobilized at the surface of a hanging mercury drop electrode was cleaved by reactive oxygen species generated by an electrochemically modulated reaction of copper ions, hydrogen peroxide and/or oxygen. The cleavage was observed in a certain potential region where redox cycling of DNA-bound Cu(II)/Cu(I) took place. In the presence of 1,10-phenanthroline the maximum efficiency of DNA cleavage was shifted to more negative potentials and the effect was enhanced.     

Spectrophotometric study of reactions of scandium,ytrium and lanthanum ions with some triphenylmethane dyes in the presence of cationic surfactants

Optimum conditions for the formation of ternary complexes of scandium, ytrium and lanthanum ions with chrome azurol S, eriochrome cyanine R and pyrocatechol violet in the presence of cetyltrimethylammonium, cetypyridinium and tetradecyldimethylbenzyl-ammonium (zephiramine) ions are described. The spectrophotometric determination of scandium with chrome azurol S and zephiramine exhibits the greatest sensitivity (? = 1.50 × 10⁵ l mol^?1 cm^?1 at 610 nm). In the spectrophotometric determination of scandium with eriochrome cyanine R and cetylpyridinium ion (? = 9.2 × 10⁴ at 600 nm), the interference caused by yttrium is the least. In the best method for yttrium (with pyrocatechol violet and zephiramine), the molar absorptivity is 3.3 × 10⁴ at 660 nm. Lanthanum does not form ternary complexes of analytical interest in these systems. Some aspects of the formation of ternary complexes with cationic surfactants are discussed.     

Microamount extraction separation of Eu(III) in the presence of lanthanide macroamounts and complexing agents in the aqueous phase

Parallel extraction (coextraction) of several elements is a phenomenon in technological processes where extraction is applied as a separation method. On the basis of the stability constants, it is possible to derive simple expressions for the prediction of effects of a complexing agent. The proposed mathematical model, the validity of which was verified by comparison with experimental data, proved to be a suitable approximation of real systems. From the technological point of view, the method presented enables to simulate the purification process of a macrocomponent according to the known dependences D_Mi,Ma=f(c _Ma ^o ).