Indium solvent extraction

Several other analytical procedures exist in which solvent extraction may be applied. Thus extraction has been used in a limited number of analyses with procedures such as (1) luminescence (fluorimetry), where, for example, the detection limit of rhodamine complexes of gallium or indium can be increased by extraction [28] (2) electron spin resonance using a spin-labelled extractant [29] and (3) mass spectrometry, where an organic extract of the analyte is evaporated onto pure AI2O3 before analysis [30]. 

Indium may be recovered from zinc ores by several patented processes. Usually it is recovered from residues obtained from zinc extraction. The residues, slags, fume, or dusts from zinc smelting or lead-zinc smelting are treated with a mineral acid. Other steps involved in recovery often vary, but mostly use solvent extraction and precipitation steps. In some processes, treatment with caustic soda yields indium hydroxide. The hydroxide is calcined to obtain oxide, which then is reduced with hydrogen at elevated temperatures to obtain the metal. Distillation or electrolysis are the final steps to... 

Relative error values for the elements ranged from zero to a high of 18% with most values being 5% or less. The 18% relative error was obtained for indium and is attributable to the low concentration of this element in the solution analyzed. Moreover, the indium values were obtained on the lower end of the working curve where the sensitivity is greatly reduced. Standard deviations and coefficients of variation for the elements of interest are at acceptable levels (less than 1% standard deviation and around 5% coefficient of variation) for this technique. Again it should be pointed out that the original purpose of the subject method was to develop a rapid routine analysis for the major and minor constituents in coal ash and related materials without the necessity of several preconcentration steps, solvent extraction techniques, or pH adjustments. 

Among other metals extracted commercially by D2EHPA, indium and thallium may be mentioned. Indium is recovered as a byproduct of copper smelting at Cerro del Pasco in Peru,140 while indium and thallium are both recovered by solvent extraction on zinc plants in the USSR.141 The extraction of indium(III) is reported to follow the stoichiometry... 

Morie, G. P., and T. R. Sweet Analysis of Mixtures of Aluminium, Gallium and Indium by Solvent Extraction and Gas Chromatography. Anal. Chem. 37, 1552 (1965). 

Indium has not proved to be an element of great interest in most environmental samples, in which it is usually present at very low concentrations. The flame AAS determination in a lean air-acetylene flame at 303.9 nm has a detection limit of around 50 ng ml -, and flame AFS is not much better.1 Flame AES in a nitrous oxide-acetylene flame gives a much lower detection limit at 451.1 nm, of around 2 ng ml"1. However the element has a low ionization potential, and addition of potassium at 5 mg ml"1 as an ionization buffer is therefore advised. Sensitivity may be enhanced by solvent extraction pre-concentration using a high extraction ratio.1 Even when pre-concentrated from geological samples by extraction into 4-methylpentan-2-one from 6M hydrochloric acid solution, ICP-AES may be the preferred method of analysis.27... 

Solvent extraction of indium(m) thiocyanate, In(SCN)3, with tributyl phosphate in hexane is markedly enhanced by the presence of background NaClOi.- it was concluded that this is due chiefly to a salting-out effect.564... 

Among the methods for the separation of small amounts of indium before its determination, the solvent extraction methods in general, and extraction of indium-iodide and -bromide complexes in particular, are of the utmost importance. 

The bromide complex of indium gives extractable ion-associates with the xanthene basic dyes Rhodamine B [49] and triphenylmethane dyes. Brilliant Green [50,51], and Crystal Violet [52], extractable into non-polar solvents. The related dye. Malachite Green, has been used to form an associate with tetra-iodoindate, extractable with benzene, hexane, and CCI4 [53]. 

In chemical shifts in n.m.r. spectra of In-halogen complexes have been measured in solution. They fall in the following sequence InCl < InBr < [In(H20)e] + < Inl. In linewidths are largely determined by quadrupole relaxation, and they may be used to study the symmetry of the complexes. Indium, when extracted into organic solvents from aqueous HCl, HBr, or HI solutions, exists as tetrahedral species, although the existence... 

Pg-Te3 units. Each of the Te atoms in the latter tritelluride anions coordinates two indium atoms in a binding mode also found in the phase [NEt4]4 [Au(Agi tAu42Sn2Te9] (x = 0.32) synthesized by solvent extraction of an intermetallic alloy. A further example for the versatility of polytelluride bridging is provided by K2Cu2Te5, in which Cu atoms are linked by intralayer... 

Gilbert TW, Newman L, Klotz P (1968) Mixed-metal hydroxycarboxylic complexes. The chromium(III) inhibition of the solvent extraction of indium(III). Anal Chem 40 2123-2130... 

These metal ions are known to form up to hexameric decanoate in noncoordinating solvents such as toluene and benzene (145, 146, 150, 155). In the indium extraction, the three species, i.e., monomer, trimer, and hexamer, all having a definite composition, are in equilibrium with each other in the organic phase (145) ... 

Indium diphenyl chloride.—Indium trichloride Irom 1-lC grams of metallic indium, and 10-77 grams of mercury diphenyl (3 mols.) are boiled with 50 c.c, of xylene for thirty-seven hours. After filtering, the residue mostly melts at 245" to 250 " C., but a portion does not melt at 295° C. The mass is extracted in a Soxhiet apparatus with dr benzene to remove any mercury compounds, and the residue in the thimble (0 647gram) is organic and found to be indium diphenyl chloride. It is a crystalline, cream-coloured powder, insoluble in the usual organic solvents, and does not melt at 350° C. 

Indium (III) chloride is another Lewis acid that is stable in water. (For the use of indium(III) chloride without organic solvents, see Chap. 8.) It has been used as a catalyst in Diels-Alder and other reactions, such as 6.20.67 After the product is extracted with an organic solvent, the aqueous layer can be used to catalyze another reaction. It should also be possible to just separate the organic layer without the use of a solvent. 

A mixture of cyclohexane carboxaldehyde (0.11 g, 1 mmol) and indium powder (0.17 g, 100 mesh, 1.5 mmol) in water (0.11 ml, 6 mmol) was added crotyl bromide (0.16 g, 1.2 mmol) slowly at room temperature in 5-mL round-bottomed flask. The reaction mixture was stirred for 12 hours followed by heated at 40 °C and monitored by TLCl3 until all the adduct was converted into its linear regioisomer. Ether was added to dilute the reaction mixture followed by 1 M hydrochloric acid to quench the reaction. The reaction mixture was extracted with ether. The combined organic layer was washed with brine, and dried over anhydrous magnesium sulfate, filtered and the solvent was removed in vacuo. 

Indium tris(pentane-l,2-dionate), In(acac)3, was first prepared in 1921 by the reaction of Hacac with freshly precipitated In(OH)3, and this remains the essence of later preparations of related compounds, which include derivatives of dibenzoylmethane, fluoro-4-6-octanedione, and various RCOCH2COCF3 compounds (R = Me, Ph, naphthyl, thienyl, efc.). Extraction into an organic solvent such as chloroform is a useful synthetic step in isolating the reaction product from aqueous solution. A direct route involving the electrochemical oxidation of indium metal in a solution of Hacac in methanol offers the advantage of a one-step synthesis,Related compounds with InO kernels include the tropolonate and 3-oxo-2-methyl-3-pyronate derivatives and it is also worth noting the anionic complex... 

General and Analytical.— An analytical method for the rapid and carrier-free separation of In (half life 2.81 d), prepared via Ag( He,2n) In or Cd(d,n) In, is based on the fact that indium, in the presence of excess Ag or Cd, is preferentially extracted from aqueous solutions into n-heptane solutions of bis(2-ethylhexyl) hydrogen phosphate (Ag and Cd remain in the aqueous phase). The In can then be stripped from the solvent phase with HCl. The separation time is <10 min. ... 

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