Binary Metal Mixtures Research Articles

Combination toxicology of copper, zinc, and cadmium in binary mixtures: Concentration‐dependent antagonistic, nonadditive, and synergistic effects on root growth in Silene vulgaris

AbstractUsing Silene vulgaris (Moench) Garcke as a test plant, the combination toxicology of Cu, Cd, and Zn was studied. Plants were exposed to single metals and binary metal mixtures in a factorial design. Root elongation after 3 d of exposure was used as a toxicity endpoint. The responses to mixtures were classified using nonaddition, response addition, and, where possible, concentration addition as reference models. In all the metal combinations tested, the nature of the joint effect appeared to be strongly concentration‐dependent. The responses were approximately nonadditive (Cu/Zn, Cu/Cd) or antagonistic (Zn/Cd) with respect to root growth inhibition as long as the concentrations of both components of the mixture were kept within the slightly toxic range. As soon as one of the mixture components exceeded a critical level of toxicity, synergism was the predominant joint effect, even when the concentration of the other component was nontoxic under single‐metal exposure. Further increases of the metal concentrations eventually decreased the degree of synergism, possibly as a result of increasing antagonisms at the level of metal uptake. The strongly synergistic effects of root‐internal metals in the more concentrated mixtures seemed to be due to sensitizing secondary effects other than saturation of common cellular detoxification mechanisms.

Investigation of Simultaneous Biosorption of Copper(II) and Chromium(VI) on Dried Chlorella Vulgaris from Binary Metal Mixtures: Application of Multicomponent Adsorption Isotherms

Although the biosorption of single metal ions to various kinds of microorganisms has been extensively studied and the adsorption isotherms have been developed for only the single metal ion situation, very little attention has been given to the bioremoval and expression of adsorption isotherms of multimetal ions systems. In this study the simultaneous biosorption of copper(II) and chromium(VI) to Chlorella vulgaris from a binary metal mixture was studied and compared with the single metal ion situation in a batch stirred system. The effects of pH and single- and dual-metal ion concentrations on the equilibrium uptakes were investigated. In previous studies the optimum biosorption pH had been determined as 4.0 for copper(II) and as 2.0 for chromium(VI). Multimetal ion biosorption studies were performed at these two pH values. It was observed that the equilibrium uptakes of copper(II) or chromium(VI) ions were changed due to the biosorption pH and the presence of other metal ions. Adsorption isotherms were developed for both single- and dual-metal ion systems at these two pH values, and expressed by the mono- and multicomponent Langmuir and Freundlich adsorption models. Model parameters were estimated by nonlinear regression. It was seen that the adsorption equilibrium data fitted very well to the competitive Freundlich model in the concentration ranges studied.

Simultaneous Biosorption of Chromium(VI) and Copper(II) on Rhizopus Arrhizus in Packed Column Reactor: Application of the Competitive Freundlich Mode

The simultaneous biosorption of Cr(VI) and Cu(II) on free Rhizopus arrhizus in a packed column operated in the continuous mode was investigated and compared to the single metal ion situation. The breakthrough curves were measured as a function of feed flow rate, feed pH, and different combinations of metal ion concentrations in the feed solutions. Column competitive biosorption data were evaluated in terms the maximum (equilibrium) capacity of the column, the amount of metal loading on the R. arrhizus surface, the adsorption yield, and the total adsorption yield. In the single-ion situation the adsorption isotherms were developed for optimum conditions, and it was seen that the adsorption equilibrium data fit the noncompetitive Freundlich model. For the multicomponent adsorption equilibrium the competitive adsorption isotherms were also developed. The competitive Freundlich model for binary metal mixtures represented most the column adsorption equilibrium data of Cr(VI) and Cu(II) on R. arrhizus satisfactorily.

High yield of single-wall carbon nanotubes by arc discharge using Rh–Pt mixed catalysts

Single-walled carbon nanotubes (SWNT) were produced using binary mixtures of the platinum-group metals as catalysts by arc evaporation in helium gas. Transmission electron microscopy and Raman scattering spectroscopy revealed that the production yield of SWNTs was remarkably enhanced when a Rh–Pt mixture was used as a catalyst. The density of SWNTs in raw soot was as high as that obtained from Fe–Ni and Y–Ni. The distribution of diameters of SWNTs was narrow (1.28±0.07 nm). The merit of this catalyst is that it is free from magnetic metals.

A comparative study for the simultaneous biosorption of Cr(VI) and Fe(III) on C. vulgaris and R. arrhizus: application of the competitive adsorption models

A process of fully competitive biosorption of Cr(VI) and Fe(III) ions to C. vulgaris and R. arrhizus from multi-component systems is described and compared to single metal ion situations in solution. The effects of the presence of Cr(VI) and Fe(III) ions together on the biosorption of Cr(VI) and Fe(III) ions were investigated in terms of initial rates of biosorption and equilibrium isotherms. Since initial biosorption rates and equilibrium metal removal decreased with increasing concentrations of the other metal ion, the combined action of Cr(VI) and Fe(III) ions on C. vulgaris and R. arrhizus was generally found to be antagonistic. In the single ion situation, the adsorption isotherms were developed for optimum conditions and adsorption equilibrium data fitted both the non-competitive Langmuir and Freundlich models. For the multi-component adsorption equilibrium, competitive adsorption isotherms were also developed. The competitive Freundlich model for binary metal mixtures was satisfactory for most adsorption equilibrium data of Cr(VI) and Fe(III) ions on C. vulgaris, while the competitive Langmuir model and the modified Langmuir model were used successfully to characterize competitive adsorption of Cr(VI) and Fe(III) ions from two component systems by R. arrhizus.

Application of multicomponent adsorption isotherms to simultaneous biosorption of iron(iii) and chromium(vi) onC.vulgaris

Although the biosorption of single metal ions to various microorganisms has been extensively studied and adsorption isotherms have been developed for single metal ion situations, very little attention has been given to the bioremoval and the expression of the adsorption isotherms of multi-metal ions systems. In this study, the competitive biosorption of iron(III) and chromium(VI) to Chlorella vulgaris from a binary metal mixture was studied and compared with the single metal ion situation in a batch stirred system. The effects of pH and single and dual metal ion concentrations on the biosorption rates and equilibrium uptakes were investigated. The optimum biosorption pH for both metal ions was determined as 2·0. Multi-metal ion biosorption studies were also performed at this pH value. It was observed that the biosorption rates and yields and equilibrium uptakes of iron(III) or chromium(VI) ions were reduced by the presence of increasing concentrations of the other metal ion. Adsorption isotherms developed for both single and dual metal ion systems at the optimum pH were expressed by the non-competitive and competitive Langmuir and Freundlich adsorption models, and model parameters were determined by computer. It was seen that the adsorption equilibrium data fitted very well to both of the models in the concentration ranges studied. ©1997 SCI

The simultaneous biosorption process of lead(II) and nickel(II) on Rhizopus arrhizus

The simultaneous adsorption of nickel(II) and lead(II) to Rhizopus arrhizus from binary metal mixtures is described and compared to studies using one metal in solution. The ability of the fungal biomass to bind metals in solution is shown to be a function of pH, the number of metals competing for binding sites in the fungal cells and metal concentrations. The effects of the presence of nickel(II) and lead(II) ions together in aquatic solutions on the biosorption of nickel(II) and lead(II) ions were investigated in terms of initial rates of biosorption, equilibrium adsorption yields and equilibrium isotherms. The effect of lead(II) ions on the uptake of nickel(II) ions was found to be antagonistic, whereas the total interactive effects of nickel(II) and lead(II) ions on the biosorption of lead(II) ions by R. arrhizus can be considered to be synergistic at a defined concentration interval. Lead(II) ions were adsorbed selectively from the binary metal mixtures.

The separation of gold by selective extraction of HAuBr4 using a poly(tetramethylene) ether glycol impregnated filter

The separation of gold(III) by selective extraction on an organic- impregnated filter (OIF) was studied. Gold was found to be rapidly extracted into the active polytetramethylene ether glycol (polyTHF) layer of the filter from strongly acidic solutions of HBr, as the HAuBr4 complex. Quantitative extraction of gold from solution was obtained with flow rates up to 600 ml min−1 through the 10.75 cm2 OIF and at ng ml−1 concentration levels. The extraction is shown to be dependent on the solution flow rate and HBr concentration as well as the filter pore size, thickness and porosity. Gold can be eluted from the filter by converting it into the AuBr4− complex using a KBr solution. The separation of gold is demonstrated from simple binary metal mixtures involving iron and cadmium, as well as from a more complicated matrix, gold ore solution.

Fully competitive biosorption of chromium(VI) and iron(III) ions from binary metal mixtures by R. arrhizus: Use of the competitive langmuir model

The uptake of heavy metal ions by microbial biomass has been extensively studied but very little attention has been given to the biosorption of multi-component systems. In this study, a process of fully competitive biosorption of chromium(VI) and iron(III) ions to Rhizopus arrhizus from binary metal mixtures is described and compared to single metal-ion situations in solution. Effects of the presence of chromium(VI) and iron(III) ions together on the biosorption of chromium(VI) and iron(III) ions were investigated in terms of initial rates of biosorption, maximum uptake capacity and equilibrium isotherms. Both chromium(VI) and iron(III) were more effectively adsorbed to the biomass at very low values of pH. The optimum initial pH for the biosorption of chromium(VI) and iron(III) ions by R. arrhizus was determined as 2·0. The initial biosorption rates and the adsorptive capacity of the biomass for chromium(VI) and iron(III) ions increased with increasing temperatures in the range 25–45°C and 25–35°C, respectively. These properties were used in the bioremoval of chromium(VI) and iron(III) ions simultaneously from binary mixtures. The instantaneous, equilibrium and maximum uptake of chromium(VI) and iron(III) was reduced by the presence of increasing concentrations of the other metal. In particular, the long-term uptake of chromium from the solution in the presence of iron was greater than the uptake of iron under the same conditions. In the single-ion situation, the adsorption isotherms were developed at different pH and temperature values and it was seen that the adsorption equilibrium data fit the non-competitive Langmuir model. The ‘best fit’ parameters for the non-competitive chromium(VI) and iron(III) biosorption at pH 2·0 and at 25°C were determined to be q s = 58·12 mg g −1 and b = 0·047 litre mg −1; q s = 34·73 mg g −1 and b = 0·066 litre mg −1, respectively. For the multi-component adsorption equilibrium, the competitive adsorption isotherms were also developed and the competitive Langmuir model was shown to be consistent with the observed uptake of multi-metal ions.

The selective biosorption of chromium(VI) and copper(II) ions from binary metal mixtures by R. arrhizus

The uptake of copper(II) and chromium(VI) ions from binary mixtures by Rhizopus arrhizus is described as a function of ion concentration, pH and temperature.

The electromagnetic separation of non-ferrous metals from each other

A laboratory, bench top, single boundary electromagnetic separator has been used to separate the binary metal mixtures of Al/brass, Cu/brass and Cu/Al, each at three different sizes. Perfect separation has been achieved in eight oat of the nine cases and almost perfect separation in the ninth. The theory which models the operation of the separator in the configuration employed is shown to provide very good predictions of the beam splitter and field setting requirements for a successful separation.

Extraction of Trivalent Metals and Separation of Binary Mixtures of Metals Using Winsor II Microemulsion Systems

Abstract We present experimental results for the extraction of a trivalent metal ion, chromium, into a water-in-oil microemulsion of Aerosol-OT. We show that it is possible to enhance the aqueous metal ion concentrations to a large extent by using suitable microemulsions as the extractant. The enhancement observed for trivalent metal ions is greater than for bivalent metal ions. The extraction process is successfully modeled by a simple electrostatic model. We also present experimental results on anion distributions in Winsor III systems and show that the microemulsion extraction process effectively separates the anions and cations in one step. Experimental results with a mixture of bivalent copper and trivalent iron solutions show that higher charge cations are preferentially extracted over the bivalent cation.

Applications involving oxidation with potassium bromate: II. Potentiometric titration of chromium alone or in mixtures

A rapid and reliable determination of chromium was developed based on bromate oxidation of chromium(III) to chromium(VI). The reaction is complete under weakly acidic conditions and with cobalt(II) present as a catalyst. Unreacted bromate and chromium(VI) are then reduced with sulfite to bromide and chromium(III). The bromide is titrated potentiometrically with mercury(I) using a silver amalgam indicator electrode. Iron(III) if present is reduced by sulfite to iron(II) and does not interfere. Some binary and ternary metal mixtures containing chromium can be resolved by the determination of chromium, alone or with another metal, by the above procedure coupled with procedures for further sample portions involving the potentiometric titration of unreacted CyDTA or iodide, or both, with mercury(II).

Titration of binary mixtures of rare earth metals based on magnetic susceptibility measurements

Gouy balance weighings are used to monitor precipitation titrations of rare earth ions with standardized oxalate solutions. A procedure is described for the analysis of binary mixtures of these compounds. The accuracy of the determinations at the millimolar level depends on the magnetic moments of the components involved but is generally better than ±4%.

Recent Advances in the Determination of Platinum Metals in Ores and Concentrates

AbstractThis report records recent developments in the methods of extraction of pt metals from ores and concetarte. Proposed procedures for the determination of platinum metals in lb buttons are included. The advances in wet separationś and det of certain binary mixtures of platinum metals are also discussed.

Recent Advances in the Determination of Platinum Metals in Ores and Concentrates

This report records recent developments in the methods of extraction of pt metals from ores and concetarte. Proposed procedures for the determination of platinum metals in lb buttons are included. The advances in wet separationś and det of certain binary mixtures of platinum metals are also discussed.

Use of Binary Light Metal Mixtures and Alloys as Additives for Solid Propellants

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The distillation of binary mixtures of metals in vacuo . Part I.―Isolation of a compound of magnesium and zinc

A product of the formula AuCd has been isolated by Heycock and Neville by placing a known quantity of gold, together with a considerable excess of cadmium, in a hard glass tube exhausted by a mercury pump, and distilling the mixture for five or six hours at a temperature as high as the glass was capable of withstanding. The composition of the non-volatile residue always approximated closely to that required by the formula AuCd, and the authors concluded that the product was a definite inter-metallic compound. It would appear, however, from the work of Vogel, that these two metals are capable of forming the compounds Au 4 Cd 3 and AuCd 3 . The compound Au 4 Cd 3 forms a series of solid solutions with cadmium, and this author concludes that the product AuCd isolated by Heycock and Neville "dürfte daher als ein kadmium-reicherer Mischkristall der Verbindung Au 4 Cd 3 aus der Reihe Be, seine Zusammensetzung als eine zufällige zu betrachten sein. At the suggestion of Mr. Heycock, the author has commenced a general investigation of the distillation of binary mixtures of metals, one of which at least is readily volatile, in order to ascertain if this method is of general applicability as a means of isolating inter-metallic compounds.