S. O. Bondareva

Fatty Imidazolines: A Novel Extractant for the Recovery of Palladium(II) from Hydrochloric Acid Solutions

The extraction of palladium(II) from hydrochloric acid solutions with a novel highly basic extractant, a mixture of homologous 1-[2-(alkanoylamino)ethyl]-2-alkyl-2-imidazolines (AAI) in toluene with 15% (v/v) of n-octanol was studied. Palladium(II) is rapidly and most effectively extracted with AAI hydrochloride at the low hydrochloric acid (chloride ions) concentration (up to 1 M) and can be completely separated from Fe(III), Cu(II), and Co(II). The palladium(II) extraction at the optimum acidity occurs via an anion-exchange mechanism with the formation of ionic associates (LH)2PdCl4 (K ex = (1.5 ± 0.2) · 104 at 0.5 M HCl) and is accompanied by the dimerization of palladium(II) in the organic phase with the formation of ionic associates (LH)2Pd2Cl6 (K dim = (3.9 ± 0.4) · 10−4 at 0.5 M HCl). The anion-exchange extraction of palladium(II) at the acidity of 0.5 M HCl is temperature independent in the range 20–49°C. Complete stripping of palladium(II) can be performed using a 5% solution of thiourea in 0.1 M HCl.

Extraction of palladium(II) from hydrochloric acid solutions with triacylated ethyleneamines

Extraction of palladium(II) from hydrochloric acid solutions with novel efficient extractants, triacylated ethyleneamines, was studied. The most effective extraction of palladium(II) was observed from 0.5–1 M HCl solutions. Extraction of palladium(II) from 1 M HCl solutions was found to occur through mixed (coordination and anion-exchange) mechanism. In the field of dominance of the anion-exchange mechanism of the extraction of palladium(II) with triacylated pentaethylenehexamine the concentration constant of palladium(II) extraction was calculated, and thermodynamic parameters of extraction were evaluated.

Bisacylated diethylenetriamines as extractants for nonferrous metals from hydrochloric acid solutions

A series of bisacylated polyethylenepolyamines with linear and α-and α,α′-branched substituents were synthesized. The effects of the number of the nitrogen atoms in the polyethylenepolyamine fragment of the reagent and of the length and branching of its alkyl radicals on the extractant distribution between the organic and aqueous phases was studied. The performance characteristics of the extractants, such as the loss with the aqueous phase, hydrolytic stability, back extraction conditions for nonferrous metals, and Zn(II)/Fe(III) and Zn(II)/Cu(II) partition coefficients, were examined.

Extraction of rhodium(III) from hydrochloric acid solutions with bis-acylated triethylenetetramine dihydrochloride

Extraction of rhodium(III) from hydrochloric acid solutions with bisacylated triethylenetetramine dihydrochloride has been studied. The optimal extraction conditions have been elaborated. At the phase contact time of 5 min rhodium(III) is extracted via the interphase anionic exchange mechanism. Concentration constants of extraction have been calculated, and thermodynamic parameters of extraction have been estimated. The extracted ion associate has been isolated and characterized by means of electronic, IR, and 13C NMR spectroscopy.

Synthesis and physicochemical properties of 1-(2-alkylamidoethyl)-2-alkyl-2-imidazolines based on α,α′-branched carboxylic acids

Condensation of diethylenetriamine with lauric, 2-ethylhexanoic, and α,α′-branched C10,12-carboxylic acids results in 1-(2-alkylamidoethyl)-2-alkyl-2-imidazolines. A stability of the synthesized compounds relative to the acid and alkaline hydrolysis was studied. Their protonation constants were determined. The effect of the structure of the alkyl substituents on the distribution of the substance between the organic and aqueous phases was examined. The principal possibility of extracting Zn(II), Fe(III), Cu(II), Co(II), Mn(II) chlorides from hydrochloric acid solutions was shown. A mixture of 1-(2-alkylamidoethyl)-2-alkyl-2-imidazolines based on the α,α′-branched carboxylic acids was suggested as a potential extractant of the metal salts from hydrochloric acid and chloride solutions.

Synthesis and extracting properties of triacylated ethyleneamines

Series of triacylated ethyleneamines for extraction of metal ions from hydrochloric acid media were synthesized. The effect of the length of the alkyl radical on the distribution of reagents among the organic and aqueous phases, stability of the reagents against hydrolysis in acid media, and extracting properties of the reagents with respect to rhodium(III) chloro complexes were studied.

Extraction of Palladium(II), Platinum(II), and Platinum(IV) by Bisacylated Diethylenetriamine from Hydrochloric Acid Solutions

The extraction properties of bisacylated diethylenetriamine are studied in the extraction of palladium(II), platinum(II), and platinum(IV) from hydrochloric acid solutions. Optimum extraction parameters are determined. The extraction of metal ions at these parameters follows an ion-associative mechanism. The concentration constants and thermodynamic parameters of extraction reactions are calculated. The feasibility of the extraction separation of palladium and platinum from base metals is verified.

Interaction of diacylated ethylenediamine with hydrochloric acid

The interaction of diacylated ethylenediamine with aqueous solutions of hydrochloric acid (1.0—12.4 mol L–1) was studied. IR spectroscopy and 1Н and 13С NMR spectroscopy revealed that the amide groups of the reagent are not protonated in the whole range of HCl concentrations. At relatively high concentrations of hydrochloric phase in the aqueous phase (<5 mol L–1), a 1 : 1 adduct with HCl is formed.

Palladium(II) Extraction from Hydrochloric Acid Solutions with Diacylated Triethylenetetramine

Extraction of palladium(II) with diacylated triethylenetetramine hydrochloride (with chloroform as diluent) from hydrochloric acid solutions was studied. Palladium(II) extraction from 3 mol/L HCl solutions occurs via anion-exchange mechanism. Concentrational constants were calculated and thermodynamic parameters of extraction were estimated.

Extraction of rhodium(III) by a bisacylated diethylenetriamine derivative from hydrochloric acid solutions

The extraction of rhodium(III) with a bisacylated diethylenetriamine derivative from hydrochloric acid solutions was studied. Optimum conditions for rhodium(III) extraction were determined. It was found that, at a contact time to 10 min, the extraction occurred by an ion-association mechanism. At a contact time longer than 10 min, rhodium(III) was extracted by a mixed mechanism with the insertion of an extractant molecule into the inner coordination sphere of the rhodium(III) ion. The composition of the extracted compound was determined using electronic, 1H and 13C NMR, and IR spectroscopy and elemental analysis, and the structure of this compound was proposed.