Copper Concentration In Solution Research Articles

The influence of mineral solubility and soil solution concentration on the toxicity of copper to Eisenia fetida SavignyThe 7th international symposium on earthworm ecology · Cardiff · Wales · 2002

Summary The OECD 14 d earthworm acute toxicity test was used to determine the toxicity of copper added as copper nitrate (Cu(NO3)2), copper sulphate (CuSO4) and malachite (Cu2(OH)2(CO3)) to Eisenia fetida Savigny. Cu(NO3)2, and CuSO4 were applied in both an aqueous (aq) and solid (s) form, Cu2(OH)2(CO3) was added as a solid. Soil solution was extracted by centrifugation, and analysed for copper. Two extractants [0.01 M CaCl2 and 0.005 M diethylenetriminpentaacetic acid (DTPA)] were used as a proxy of the bioavailable copper fraction in the soil. For bulk soil copper content the calculated copper toxicity decreased in the order nitrate > sulphide > carbonate, the same order as decreasing solubility of the metal compounds. For Cu(NO3)2 and CuSO4, the LC50s obtained were not significantly different when the compound was added in solution or solid form. There was a significant correlation between the soil solution copper concentration and the percentage earthworm mortality for all 3 copper compounds (P ≤ 0.05) indicating that the soil pore water copper concentration is important for determining copper availability and toxicity to E. fetida. In soil avoidance tests the earthworms avoided the soils treated with Cu(NO3)2 (aq and s) and CuSO4 (aq and s), at all concentrations used (110–8750 μg Cu g–1, and 600–8750 μg Cu g–1 respectively). In soils treated with Cu2(OH2)CO3, avoidance behaviour was exhibited at all concentrations ≥3500 μg Cu g–1. There was no significant correlation between the copper extracted by either CaCl2 or DTPA and percentage mortality. These two extractants are therefore not useful indicators of copper availability and toxicity to E. fetida.

The influence of mineral solubility and soil solution concentration on the toxicity of copper to Eisenia fetida Savigny : The 7th international symposium on earthworm ecology · Cardiff · Wales · 2002

The OECD 14 d earthworm acute toxicity test was used to determine the toxicity of copper added as copper nitrate (Cu(NO3)2), copper sulphate (CuSO4) and malachite (Cu2(OH)2(CO3)) to Eisenia fetida Savigny. Cu(NO3)2, and CuSO4 were applied in both an aqueous (aq) and solid (s) form, Cu2(OH)2(CO3) was added as a solid. Soil solution was extracted by centrifugation, and analysed for copper. Two extractants [0.01 M CaCl2 and 0.005 M diethylenetriminpentaacetic acid (DTPA)] were used as a proxy of the bioavailable copper fraction in the soil. For bulk soil copper content the calculated copper toxicity decreased in the order nitrate > sulphide > carbonate, the same order as decreasing solubility of the metal compounds. For Cu(NO3)2 and CuSO4, the LC50s obtained were not significantly different when the compound was added in solution or solid form. There was a significant correlation between the soil solution copper concentration and the percentage earthworm mortality for all 3 copper compounds (P ≤ 0.05) indicating that the soil pore water copper concentration is important for determining copper availability and toxicity to E. fetida. In soil avoidance tests the earthworms avoided the soils treated with Cu(NO3)2 (aq and s) and CuSO4 (aq and s), at all concentrations used (110–8750 μg Cu g–1, and 600–8750 μg Cu g–1 respectively). In soils treated with Cu2(OH2)CO3, avoidance behaviour was exhibited at all concentrations ≥3500 μg Cu g–1. There was no significant correlation between the copper extracted by either CaCl2 or DTPA and percentage mortality. These two extractants are therefore not useful indicators of copper availability and toxicity to E. fetida.

Investigation into sorption processes in the anodic stripping voltammetric speciation of Cu in natural waters

In the anodic stripping voltammetric speciation of copper significant errors may be introduced as a result of sorption of Cu 2+ onto active surfaces of the voltammetric cell assembly. A correction method was developed based on monitoring of the total copper concentration in solution using a 64 Cu -radiotracer; additionally this allowed us to study sorption phenomena in the voltammetric cell assembly. For copper speciation in a fresh water sorption-corrected complexing capacity data (total natural ligand concentration and conditional stability constant of formed complex) showed considerable discrepancies with uncorrected data. From the same sorption data it could be deducted that this was accountable to the presence of two active surface sites in the voltammetric cell assembly.

Modelling copper adsorption on olivine process dust using a simple linear multivariable regression model

This paper investigates the adsorption of copper on process dust from the production of olivine aggregates as a function of pH and the concentration of copper in solution. The olivine process dust, containing more than 90% forsterite, was retrieved from the dust removal system at A/S Olivin’s processing plant at Åheim in western Norway. Following characterisation of the material, batch adsorption experiments were conducted at 25 °C at an ionic strength of 0.05 M using a fixed adsorbent dose of 10 g/l and initial copper concentrations ([Cu] i) ranging from 20 to 600 μM (i.e. 1.27–38.1 mg/l). The final pH in solution (pH f) was varied from approximately 4 to 6. The obtained results show that the olivine process dust is capable of greatly reducing the concentration of copper in solution, even when exposed to relatively high initial copper concentrations. A linear multivariable regression model (LMVR model) was fitted to the logarithmically transformed experimental data. The good fit of the LMVR makes it possible to estimate retention as a function of pH f and the final copper concentration ([Cu] f), or, alternatively, [Cu] f as a function of pH f and [Cu] i. From an environmental engineering point of view, the latter would often be of greater interest since the success criteria usually are related to the resulting concentrations in solution.

Effect of ultrasound on the removal of copper from the model solutions for copper electrolysis process

A novel combination of an ultrasonic field with electrolysis for the removal of copper is studied. In the ultrasonic field, cavitation acts as jets and agitates the solution and breaks the barrier layer between the cathode surface and the bulk of the solution, thus increases the metal deposition on the cathode surface. The results show that an ultrasonic field is successful for the removal of low copper concentrations in solution.

A study on the Manufacture of the CuO Powder from Copper Chloride Solution by Spray Pyrolysis Process

In this study copper chloride(CuCl<TEX>$_2$</TEX>) solution was used as raw material to produce the fine copper oxide powder which has less than 1 <TEX>$\mu\textrm{m}$</TEX> average particle size and has uniform particle size distribution by spray pyrolysis process. In the present study, the effects of reaction temperature, the injection speed of solution and air, the nozzle tip size and the concentration of raw material solution on the properties of produced powder were studied. The structure of the powder became much more compact with increasing the reaction temperature regardless of copper concentration of the raw material solution. The particle size of the powder increased accordingly with increasing the reaction temperature in case of 30 g/<TEX>$\ell$</TEX> copper concentration of the solution. The particle size of the powder increased accordingly, and the surface structure of the powder became more porous with increasing the copper concentration of the raw material solution. When copper concentration in raw material solution was more than 100 g/<TEX>$\ell$</TEX>, all produced powder was CuCl regardless of reaction temperatures. When copper concentration in solution was below 30 g/<TEX>$\ell$</TEX> and reaction temperature was higher than 90<TEX>$0^{\circ}C$</TEX>, CuO was the main phase. The surface of the powder tended to become porous with increasing the injection speed of solution. Particle size was increased and the surface of the powder showed severely disrupted state with increasing the nozzle tip size. The particle size was decreased and the particle size distribution was more uniform with increasing the air pressure through the nozzle.

The Stability of Monolith CuZSM-5 Catalysts for the Selective Reduction of Nitrogen Oxides with Hydrocarbons: I. Synthesis and Characterization of Bulk CuZSM-5 Catalysts

The effects of ion-exchange conditions (the pH, the copper concentration in solution, and the solution-to-zeolite volume ratio) and the Si/Al atomic ratio of HZSM-5 zeolite on the concentration and state of copper in bulk CuZSM-5 catalysts and on the catalytic activity in the selective reduction of NO with propane were studied. It was found that the concentration and state of copper in the catalysts essentially depend on the pH of the solution used for ion exchange and on the copper concentration in this solution. An increase in the solution-to-zeolite volume ratio has almost no effect on the above characteristics. Regardless of the Si/Al atomic ratio of zeolite and of the pH of solution, a maximum activity (NO conversion) of the resulting catalyst is attained even at an exchange level (Cu/Al) close to 100% (80–140%). The absolute value of this catalytic activity depends only on the reaction temperature and is equal to 22–31% at 300°C or 85–97% at 400–500°C. The above exchange level is maximally attainable at pH ∼6 in the chosen range of copper acetate concentrations in solution (2–10 mg/ml accounted as CuO). An increase in the pH of ion exchange up to ∼100% allows a wider variation in the exchange level and the state of copper in the zeolite with the same range of copper concentration in the solution. However, at Cu/Al ≫ 100% (up to ∼430%), the catalyst activity is independent of the exchange level. The state of copper in freshly prepared samples affects the stability of the catalysts in storage. In turn, the state of copper depends on ion-exchange conditions and the Cu/Al ratio.

Cyanidation of a copper-gold ore

A free milling gold ore, which contains 0.4% copper as chalcopyrite, was treated with cyanide. In the pre-leaching, the kinetics of oxidation of soluble sulphides are not an accurate indication for the length of the treatment. Efficient gold leaching is achieved only under specific conditions using oxygen, lead nitrate and a high concentration of free cyanide. The addition of lead nitrate results in a higher gold extraction, although cyanide consumption cannot be reduced below 1.85 kg/t without a drop in the extraction. Without lead nitrate, the gold recovery is lower than 90% but with lead nitrate, it reaches 98%. The addition of oxygen increases the gold recovery by 1.5%. The extraction of gold is not sensitive to lead nitrate additions when higher than 300 g/t. The redox potential values could thus be used as control parameters for lead nitrate addition, at the different stages of cyanidation, to indicate the state of the system. The increase of lead nitrate concentration inhibits the dissolution of chalcopyrite but the approach used was not efficient enough to decrease the cyanide consumption. The high concentration of copper in solution requires a concentration of NaCN in the range of 700 mg/L. When the average NaCN concentration is lower than 640 mg/L, gold recovery drops significantly. It was also found that lead nitrate can be added directly at the start of cyanidation to achieve a performance equivalent to the situation in which it is added during pre-leaching.

Effects of Copper on the Growth, Uptake and Distribution of Uptake in Roots and Shoots of Carrot Plants Treated with Copper Solutions by Either Root-Treatment or Foliar-Treatment

Effect of treatment of carrot plant with copper solutions have been investigated. The growth of plant as well as its uptake of copper and the distribution of this uptake between roots and shoots of the treated plants were followed in the study. Two types of treatment have been used: root-treatment and foliar- treatment. Copper solutions with concentrations of 0.3 - 7.6 ppm were used for root - treatment (200 nil batches repeated for 12 times over the whole period of growth) and for foliar treatment (50 ml batches repeated for 12 times over the whole period of growth). The root -treatment of the plants resulted in 10 - 63% reduction in the dry weight of plant while foliar - treatment resulted in 2 - 69% weight reduction. Comparing the two types of treatment (via determination of amounts of copper causing 50% growth inhibition) indicated a much higher effect of foliar - treatment over root - treatment on the growth of the plants and more obviously on the growth of the shoots. The concentration and total content of copper in the treated plants as well as in their roots and shoots increased with the increase of copper concentration in solutions used for either the root - treatment or the foliar-treatment. The copper content of the shoots of treated plants exceeded the content in their roots, and this was more so in the case of foliar - treatment.

The Uptake and Accumulation of Zinc and Copper From Solution by two Species of Talitrid Amphipods (Crustacea)

The exposure of two species of talitrid amphipods(Orchestia gammarellusandOrchestia mediterranea)to a range of zinc and copper concentrations in solution has enabled the categorization of the mode of metal accumulation adopted by these supralittoral amphipods. Both species showed net accumulation of dissolved zinc and copper at all experimental exposures between 20 and 1000 μig Zng 1 and 13 and 1000 μg Cu 1 in artificial sea-water. Studies using Zn have shown that the zinc uptake rates of both species (0·430 μg Zn g d, SE 0·032 and 0·408 µg Zn g d, SE 0·073 forO. gammarellusandO. mediterranearespectively at 10°C in 31·6 μg Zn 1) are not significantly different, and are low in comparison with other crustaceans. Laboratory results are related to field conditions, and it is concluded that Firth of ClydeO. gammarellusare more dependent upon a food source in order to meet both their copper and zinc requirements than areO. mediterraneawhich are able to obtain sufficient metabolic copper from solution. The use of talitrid amphipods in zinc and copper biomonitoring programmes is also discussed.

SORPTION EQUILIBRIUM OF COPPER BY PARTIALLY-COAGULATED CALCIUM ALGINATE GEL

Abstract The sorption equilibrium of dissolved copper by spherical partially-coagulated gels of calcium alginate was investigated in this work. The gels were formed by dispensing a viscous algin (food grade sodium alginate from kelp) solution with a multi-tip dispenser into 0.05 M CaCl2 solution in a loop fluidized bed reactor. The resultant semi-rigid spherical gels were then transferred to another reactor operated batch wise to absorb dissolved copper at low concentrations (10-40 ppm). When the concentration of the inert neutral salt NaNO3, added to the reactor fluid was 0.01 M, the amount of copper absorbed was found to be substantially higher than that at 0.1 MNaN03. The conventional Langmuir's model based on the concentration of copper in solution yielded different values of conditional stability constant at different ionic strengths in the reactor fluid. However, by defining the copper-binding stability constant on the basis of copper activity in the gel phase with the competition from calcium for m...

Structural and chemical characterization of gallstones resistant to dissolution therapy

X-ray diffraction, i.r. spectroscopic, and chemical analyses have been carried out on radiolucent gallstones resistant to dissolution therapy. Cholesterol represents the main component of all the examined stones, while the ratio between the amounts of pigmented material and calcium carbonate is about 1 in the inner and outer layers of the stones and 3 in the medial layer. Calcium carbonate is present in two distinct crystalline forms: vaterite, which is the main inorganic crystalline phase, and calcite. The cell parameters of vaterite and calcite are shorter in the inner and outer layers of the stones than in the medial layer. The observed variation of the cell parameters has been related to the substitution of copper to calcium in the carbonate structures, on the basis of the data obtained on vaterite and calcite synthesized in presence of different copper concentrations in solution. The results indicate that the failure of the dissolution therapy can be related to the inhomogeneous distribution in the stones of calcium carbonate and calcium bilirubinate.

The variation in apparent trace metal complexing capacity of natural waters with plating potential using anodic stripping voltammetry

Abstract The measurement of the copper complexing capacity of natural waters by anodic stripping voltammeting (ASV) has been shown to be dependent on the plating potential used to measure the concentration of electroactive copper in solution. Results are presented for the complexing capacities and conditional stability constants of 3 Papua New Guinean lake waters at pH 6.0 measured at the plating potentials ‐0.3, ‐0.6, ‐0.9 and ‐1.2v versus SCE. The results are rationalised using both a single ligand model and a two ligand model.

The adsorption of copper by soil samples from scotland at low equilibrium solution concentrations

At low solution concentrations of copper in the presence of 0.05 M CaCl 2, adsorption isotherms for copper on soil samples were essentially linear. Although no direct correlations were found between isotherm gradients and individual soil properties, the gradients were of the same order of magnitude as predictions based on gradients obtained for some specific soil components. The soil components which appear to be most important in copper adsorption and which were used to obtain the predictions were organic matter and iron and manganese oxides. The amounts of adsorbed copper remaining isotopically exchangeable or extractable with EDTA in the short term increased with the amount of copper adsorbed but the proportions of adsorbed copper estimated by each of these techniques remained constant. Concentrations of copper in solution increased (adsorption decreased) at pH values below 4.5 and above 6.5.

Complexation and toxicity of copper and the free metal bioassay technique

The concentrations of free and total copper toxic to Daphnia and guppies were determined in inorganic media with and without addition of various concentrations of β-alanine, glycine, glutamic acid or Tris. Free copper concentrations were determined using a cupric ion electrode. Stability constants calculated for each of the detected complexes compared favourably with previously published values, with the possible exception of the Cu(OH) 2 complex. Free copper concentrations in solutions equally toxic to Daphnia were observed to vary greatly, primarily because of the toxicity of copper amino acid complexes to this organism. The copper/amino acid complexes were, nevertheless, less toxic than the free copper ions. The copper/β-alanine complex was observed to be less toxic to guppies than to Daphnia, indicating a difference in sensitivity to different copper complexes in different organisms. Copper/Tris complexes were found to be only slightly toxic to both Daphnia and guppies. A bioassay technique for determining free copper concentrations by comparing copper toxicity before and after addition of Tris was tested and verified. Although free metal concentrations can be determined from properly conducted bioassays, the variation in free metal concentration in equally toxic solutions demonstrates that free metal concentrations cannot be calculated by simply comparing metal toxicity in a test solution with toxicity of the same metal in a standard solution with known free metal concentration, unless it is known that no complexes are present in the test solution which can form toxic complexes with the metal.

The possible polyphyletic origin of copper tolerance inAgrostis tenuis (Gramineae)

The effect of increased copper concentration in solution on the rooting of seven copper tolerant populations ofAgrostis tenuis has been examined using the regression technique ofFinlay &Wilkinson (1963). Three types of response to increased copper concentration have been detected, and it is suggested that these reflect a different genetic control of copper tolerance in different populations.

Extraction of Theion-Pair [(C4 H9) 4 N + 2 [Cu(SCN)2 4 by MIBK: Spectrophotometric Determination of Copper

Abstract This paper reports the extraction of the ion-pair formed by the tetrabutylammonium cation and the copper complex with thiocyanate from aqueous to MIBK solutions. The variables which affect the extraction efficiency were investigated and the optimal conditions for the efficiency to be almost 100 per cent were determined. The extraction can be accomplished between pH 1 and 7 and an excess of ammonium thiocyanate and tetrabutylammonium chloride is necessary. The absorption spectrum of the ion-pair in MIBK has a maximum at 510 nm. At 510 nm the absorbance is proportional to the concentration of copper in solution. Thus, the spectrophotometric determination of copper is possible, after the extraction by MIBK. Beer's Law is verified for a range between 3.8 × 10−5 and 7.6 × 10−4 M. after interferences were investigated, the precision and accuracy of this method were checked by determining the copper content in an alloy whose composition was certified by British Chemical Standards.

The effect of ammonium and nitrate nitrogen sources on copper uptake and amino acid status of cereals

The effects of different nitrogen sources (NH4, NO3, and NH4 NO3) on the uptake of copper by wheat and barley growing in solution culture were compared in three experiments. Both the copper concentration and weight gain of shoots and roots were found to decrease in the order NO3>NH4 NO3>NH4 irrespective of the solution copper concentration. Ammonium nitrogen was also found to decrease the copper concentration of wheat grown on a copper deficient soil compared with a nitrate source of nitrogen.

Investigation of hydrophobic porous electrodes. II. Pseudocapacitance changes during underpotential copper deposition

Differential capacitance measurements in 96%o-phosphoric acid at 160° C have been used to follow the underpotential deposition of copper on supported platinum in a porous electrode. At a potential in the range 0·2–0·3 V versus RHE the capacitance,C, increased as copper deposition proceeded and a plot ofC versust 1/2 was linear during a substantial part of the deposition process. The slope dC/dt 1/2 was proportional to the copper concentration in solution, suggesting that the Cu/Cu2+ pseudocapacitance reflected the quantity of copper deposited and that copper deposition was diffusion controlled. The effective diffusion coefficient estimated from the results was 10−7 cm2 s−1 — some 40 times smaller than the copper ion diffusion coefficient measured separately. At potentials of 0·4 V and above, capacitance measurements could not be used to follow copper deposition because the Cu/Cu2+ pseudocapacitance decayed with time.

Investigations into the electroreduction of copper(II) ions on chalcocite in ammonia solutions using the rotating disc electrode method

Investigations into the electroreduction of copper(II) ions in ammonia solutions on a disc electrode made of synthetic chalcocite having a deficiency of copper atoms have been presented. It has been concluded that within the range of the diffusion controlled process copper(II) ions are the diffusing substance, at the same time in the course of the reaction two electrons are exchanged. The kinetic parameters for the electroactivating process have been estimated. With a higher concentration of copper in solution an inhibition process has been observed, probably caused by a slow transport rate of the species in the material of the electrode. In the system studied the phenomenon of a partially blocked electrode surface does not occur according to the Landsberg model.