Metals extraction with carboxylic acids. I. Composition of complexes with nickel,cobalt(II) and iron(III)

A computer method has been developed to calculate the probable composition of complexes formed in the organic phase during the recovery of various metal ions from aqueous solutions by means of acidic extractants.The calculations suggest that with Versatic 10, nickel and cobalt form dimeric complexes. The number of covalently bound carboxylate groups depends on the loading of the extractant and may vary from 2 to $\text{1}\text{1}\text{2}$ to 1 per metal ion. The apparently “vacant” covalent bonds of the metal might carry hydroxyl groups. The number of solvating acid molecules per metal ion is 2 in the case of nickel and 0, 1 or 2 for cobalt.With octanoic acid cobalt probably forms mainly monomeric complexes. The number of covalently bound carboxylate groups is 2 per metal atom, even at high loadings. The number of solvating acid molecules varies with the degree of loading and may be 0, 1 or 2 per metal atom.The extraction of iron(III) with Versatic 10 has also been studied. Several possible species both dimeric and trimeric and containing both covalently bound carboxylate groups and solvating acid molecules and possibly also hydroxyl groups were indicated.     

Resonance Raman spectra of iron(III)-, copper(II)-, cobalt(III)-, and manganese(III)-transferrins and of bis(2,4,6-trichlorophenolato)diimidazolecopper(II) monohydrate, a possible model for copper(II) binding to transferrins

Fe(III), Cu(II), Co(III), and Mn(III) complexes of ovo- and human serum transferrins show resonance enhanced Raman bands near 1600, 1500, 1270, and 1170 cm-1 upon excitation with laser frequencies which fall within the visible absorption bands of those metalloproteins. Comparison of the visible absorption and resonance Raman spectra of the Cu(II)-transferrin complexes with those for the Cu(II) model compound, bis(2,4,6-trichlorophenolato)diimidazolecopper(II) monohydrate, indicates that the resonance Raman bands are due to enhancement of phenolic vibrational modes. For the model (Cu(II) compound, a normal coordinate analysis was used to aid our assignment of the observed resonance bands at 1562, 1463, 1311, and 1122 cm-1 to A1 vibrational modes of the 2,4,6-trichlorophenolato moiety. These assignments are consistent with those made for Cu(II)-transferrins. The latter assignments were based upon calculated A1 frequencies for p-methylphenol (Cummings, D.L., and Wood, J.L. (1974), J. Mol. Struct. 20, 1). The wavelength shifts in the resonance bands for the model compound from those for Cu(II)-transferrins are due to the influence of the chloro substituents on the planar vibrations of phenol. These results clearly identify tyrosine as a ligand in copper binding to transferrins.     

The extraction of copper(II) and iron(III) from chloride and sulphate solutions with LIX 64N in kerosene

A comparison has been made of the extraction of Cu(II) and Fe(III) from chloride and sulphate solutions with LIX 64N in kerosene. The effects on extraction of pH, anion concentration, and temperature were examined, and attention was paid to the ionic strength of the aqueous media, some of which contained aluminium and magnesium; extraction was carried out under ‘practical’ rather than ‘ideal’ conditions. Extraction of both Cu and Fe was enhanced from chloride solutions compared with sulphate; although separation of Cu from Fe was slightly reduced, extraction of Cu from chloride liquors appears to be applicable to commercial leach solutions.     

The effect of Fe(II) and Fe(III) on the efficiency of copper electrowinning from dilute acid Cu(II) sulphate solutions with the chemelec cell. Part II. The efficiency of copper electrowinning from dilute liquors

This programme of work forms part of a study into the application of the Chemelec cell for direct electrowinning of copper from dilute leach liquors. A typical liquor is defined as containing less than 2 g l^?1 Cu(II), with an equivalent or greater concentration of iron as Fe(II) and Fe(III). Electrowinning experiments using simulated liquors showed that the current efficiency decreased in proportion to the increase in the Fe(III) concentration. A current efficiency of less than 30% was obtained during the electrowinning of a copper solution (1–2 g l^?1 Cu) with an Fe(III) concentration of 0.5–3.0 g l^?1. Electrowinning from leach liquors (1–2 g l^?1 Cu, 1–2 g l^?1 Fe(III) and 1–5 g l^?1 Fe(II)) showed improved efficiencies. A current efficiency of 47% was obtained for copper removal to less than 50 mg l^?1, with an electrolytic energy cost of about £198 per tonne at 3.3p per kWh. The impurity content of the copper was low, the most significant impurity being lead at 0.012%. This work has shown that the Chemelec cell can achieve reasonable efficiencies for direct electrowinning from dilute leach liquors. Further work is required in order to confirm the efficiency of electrowinning and to assess the operating and capital costs of a commercial cell.     

The effect of Fe(II) and Fe(III) on the efficiency of copper electrowinning from dilute acid Cu(II) sulphate solutions with the chemelec cell: Part I. Cathodic and anodic polarisation studies

The results are presented from an investigation into the effect of the Fe(III) and Fe(II) concentration on the current efficiency for copper electrowinning using the Chemelec cell. The results are from polarisation studies of acidic sulphate electrolytes containing Cu(II), Fe(II) and Fe(III). The mass transfer coefficients for these cationic species are determined, and the effect of using different anode materials on the overvoltage for the oxidation of Fe(II) and oxygen evolution is also examined.     

Polymeric pseudocrown ethers. III. The complexation with iron(III) in phosphoric—hydrochloric acid mixtures

Polymeric pseudocrown ethers, incorporating oxyethylene and oxypropylene units, extract FeCl₄^? from mixed hydrochloric and phosphoric acids. The complexation depends on hydrochloric acid concentration and becomes efficient when the HCl concentration exceeds 4 M. The regeneration of the polymers is accomplished with water. Column tests have been shown to separate iron very efficiently from phosphoric acid, which is recovered quantitatively. In comparison, Amberlyst A-21, a weak-base anion exchanger, shows affinity for phosphoric acid, making the separation between iron and phosphorus difficult.     

2,7-双(5-羧基-1,3,4-三氮唑偶氮)-变色酸分光光度法测定铜的研究

研究了新显色剂2,7-双(5-羧基-1,3,4-三氮唑偶氮)-变色酸(简称BCTZACA)与Cu(的显色反应条件。结果表明,在pH5·0的HAc-NaAc介质中,Cu(与BCTZACA形成稳定的紫色络合物,络合物的λmax=570nm,试剂的λmax=489nm,络合物的表观摩尔吸光系数ε=4·58×104,Cu(在0~0·8mg/L范围内符合比尔定律。所拟方法直接用于镁合金和铝合金样品中微量铜的测定,加标回收率为101·8%~102·0%,RSD为1·9%~3·6%(n=6),结果满意。     

2-(2-咪唑偶氮)-5-二甲氨基苯甲酸分光光度法测定铜

研究了新显色剂2-(2-咪唑偶氮)-5-二甲氨基苯甲酸(IZDBA)与铜的显色反应。结果表明,在pH 4.0的HAc-NaAc缓冲溶液中,IZDBA与Cu(Ⅱ)形成稳定的摩尔比为2∶1的紫红色络合物,其最大吸收波长为600 nm,表观摩尔吸光系数为3.62×104L.mol-1.cm-1,Cu(Ⅱ)质量浓度在0.08~0.8 mg/L范围内符合比尔定律。本方法可不经分离直接测定铝合金和镁合金样品中微量的铜,测定结果与认定值相符。     

Solubilities,densities and electrical conductivities of aqueous copper(I) and copper(II) chlorides in solutions containing other chlorides such as iron,zinc, sodium and hydrogen chlorides

With a view to industrial applications, solubilities, densities and electrical conductivities of aqueous copper(I) and copper(II) chlorides were measured in solutions containing other chlorides like those of iron, zinc, sodium and hydrogen.In these solutions copper(I) chloride shows a behaviour similar to that observed in pure CuClNaClHCl solutions. Increasing the FeCl₂ concentration decreases the solubility of CuCl less than increasing the ZnCl₂ concentrations does. Moreover, increasing total Cl^? concentration increases CuCl solubility if Cl^? is added as FeCl₂ and decreases CuCl solubility if Cl^? is added as ZnCl₂. NaCl solubility remains unchanged by FeCl₂ additions and is increased by ZnCl₂ additions.Copper(II) chloride also shows in these solutions a behaviour similar to that observed in pure CuCl₂NaClHCl solutions. FeCl₃ additions decrease CuCl₂ · 2 H₂O solubility in a more drastic manner than ZnCl₂ additions. However, NaCl additions have a much higher effect.These results can be qualitatively interpreted when taking into account the relative Cl^? donor or acceptor character of the constituent chloride salts of the solution.FeCl₂ additions slightly decrease the electrical conductivity of Cu(I) solutions. However, this can easily be compensated by a slight increase in temperature or in acidity.     

Metals extraction with carboxylic acids. II. Effect of temperature on the extraction of Cu,Ni, Co(II), Zn,Fe(III) and Co(III)

The relation between the extraction temperature and the coefficient of distribution of various metals between aqueous phases and kerosene solutions of Versatic acid has been investigated.Using a mathematical procedure, it was established that with increasing temperature the distribution coefficient changes if the composition of the metal-Versatic complex is temperature-dependent. In the case of trivalent iron a reversible increase in distribution coefficient occurs when the temperature is raised. It is suggested that this is due to a reversible depolymerization of the complex. The distribution coefficient of trivalent cobalt also increases with temperature, but here the increase is irreversible, possibly because the number of covalently bound carboxylate groups changes.In general, the distribution coefficient of metals which do not show variations in the composition of their complexes with Versatic, such as Cu, Ni, Co(II) and Zn, does not change appreciably with temperature.     

Equilibrium and kinetic studies of iron(II) and iron(III) complexes of some alpha (N)-heterocyclic thiosemicarbazones. Reduction of the iron(III) complexes of 2-formylpyridine thiosemicarbazone and 2-acetylpyridine thiosemicarbazone by cellular thiol-like reducing agents

PURPOSE: To examine the association between communication with parents and self-harm in 14-19-year-old adolescents. METHODS: A total of 36 female and 16 male adolescents presenting to the accident and emergency department of a general hospital; 52 hospital-based controls were interviewed and studied using the following scales: Parent-Adolescent Communication Scale, Family Adaptability and Cohesion Evaluation Scale, Adolescent-Family Inventory of Life Events and Changes Scale, Children's Depression Index, and Nowicki-Strickland Locus of Control Scale. RESULTS: The absence of a family confidant was very strongly associated with adolescent self-harm. Despite controlling for a wide range of possible causal factors, poorer parent-adolescent communication remained strongly associated with self-harm. The effect of poorer communication on self-harm was strongest in the group with and internal locus of control. CONCLUSIONS: Impairment of communication between adolescents and their parents may be important in the origins of adolescent self-harm.     

2-(5-羧基-1,3,4-三氮唑偶氮)-5-二乙氨基苯甲酸分光光度法测定铜

首次合成了新显色剂2 (5 羧基 1,3,4 三氮唑偶氮) 5 二乙氨基苯甲酸(简称CTZABA),研究了它与Cu2+显色反应的条件。结果表明,Cu2+在pH3 0的HAc NaAc缓冲溶液中与CTZABA形成稳定的组成比为1∶2的紫色络合物,络合物的λmax=585nm,试剂的λmax=498nm,对比度△λ=87nm,络合物的表观摩尔吸光系数ε=5 14×104,Cu2+在0～0 6mg/L范围内符合比尔定律。本方法可不经分离直接测定铸造镁合金和锰黄铜合金样品中的金属铜,结果令人满意。     

Horsetail (Equisetum telmateia) ferredoxins I and II. Amino acid sequences

Two ferredoxins were isolated from horsetail (Equisetum telmateia) and their amino acid sequences were determined by use of a sequence analyzer in combination with carboxypeptidase digestion and manual Edman degradation of tryptic peptides of carboxymethyl-ferredoxins. Ferredoxins I and II each had only four cysteine residues in a total of 95 and 93 residues, respectively. The amino-terminal residues of both ferredoxins were heterogeneous, but alanine was concluded to be their genuine terminal residue. The comparison of these isozymelike molecules showed 29 differences in amino acid residues with three inverted replacements. One gap was inserted in ferredoxin II at position 32 to align the ferredoxins with greatest homology. Despite the many differences in amino acid residues there was no difference in net charges of the two ferredoxins.     

1-(2-吡啶偶氮)-2-萘酚分光光度法测定硫酸阳极氧化液中铜

研究了铜与1-(2-吡啶偶氮)-2-萘酚(PAN)的显色反应,建立了测定硫酸阳极氧化液中铜的新方法。以TritonX-100为增溶增敏剂,明胶作稳定保护剂,在酸性条件下Cu-PAN络合物稳定保持在水相中,直接进行光度分析。该络合物在558nm处有最大吸收峰,其表观摩尔吸光系数ε=2.25×104L.mol-1.cm-1。方法检出限为0.028μg/mL,线性范围为0～3.2μg/mL,用于测定硫酸阳极氧化液中的铜,加标回收率为98.2%～105.6%,相对标准偏差≤0.34%。     

The coprecipitation behavior of Co(II) and Ni(II) with Fe(III), Cr(III) and Al(III) from aqueous ammoniacal solutions

The coprecipitation of cobalt(II) and nickel(II) with iron(III), chromium(III) and aluminum(III) from ammoniacal solutions has been investigated. The coprecipitation behavior was found to be very sensitive to the solution pH and total ammonia concentration. Co(II) and Ni(II) can be precipitated from low ammonia concentration solutions but are readily redissolved at higher ammonia concentrations. The coprecipitate of divalent and trivalent species was found to contain very large amounts of the divalent metals (up to a mole ratio M M(II)/M(III) of 2.5) when aluminum was the trivalent species, whereas with iron(III) or chromium(III), the ratio was only 0.5.     

Leaching of copper(I) sulphide by sulphuric acid solution with addition of sodium nitrate

Finely grained samples of copper(I) sulphide were leached by H₂SO₄ solution with added NaNO₃. The occurrence probability of chemical reactions was analysed based on literature data and products which were formed during the process and the overall leaching reaction was defined. The effect of temperature, concentration of NaNO₃ and H₂SO₄, stirring speed, phase ratio and time, on the leaching degree of copper was studied. The quantity of copper dissolved increases with growth of the values of all the parameters. Kinetic analysis shows that the leaching mechanism is very complex. By using appropriate mathematical kinetic models, it is found that the leaching rate is chemically controlled. It was concluded that the leaching reaction is first order with respect to the concentration of NaNO₃ and second order with respect to the concentration of H₂SO₄.