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New capabilities in extraction of platinum metal chloride complexes with oxygen-containing extractants

“…Here, a negative factor was also wide dispersion of K D values given by different authors. For instance, the dispersion of published data on the maximal K D values for platinum metals in the most popular system HCl-tributyl phosphate [5] The goal of the present work was to analyze factors responsible for dispersion of K D values and substantiate capabilities for improvement of the extraction efficiency of platinum metal chloride complexes with oxygen-containing extractants on the basis of the results of our previous studies [6][7][8][9][10][11][12][13][14]. While performing this study, specific attention was given to the synthesis of initial chloride complexes of each metal and development of procedures for their isolation from solution.…”

“…The observed increase in the efficiency of extraction of platinum metal chloride complexes in going from hydrogen chloride solutions to acid sulfate-chloride solution is general for all oxygen-containing extractants acting according to the hydrate-solvate extraction mechanism [1]. In the extraction of platinum(IV) and palladium(II) chloride complexes with higher alcohols the K D value increases by 1.5-2 orders of magnitude in going from chloride to mixed chloride-sulfate solution, other conditions being comparable [12]. For instance, the K D value for the extraction of Pt(IV) chloride complexes with heptan-1-ol attains 20, which is comparable with the maximal K D value in the extraction from acid chloride solutions with tributyl phosphate.…”

“…The maximal K D values for generally prevailing [OsCl 6 ] 2-species in acid chloride solutions and chloride-sulfate solutions with the HCl concentration fixed at 1 M were 150 and 250, respecttively. Using K D values for particular Os(IV) species [12] we estimated the contributions of each of them to the overall K D value for their mixtures corresponding to real solutions. Taking into account that all experiments were performed with freshly prepared solutions, variation of the component ratio during the time necessary for extraction equilibration may be neglected.…”

“…The experimental values were determined for a series of specially prepared solutions with different concentration of pure osmium(IV) complexes isolated by extraction chromatography. The calculations were performed assuming additivity of contributions of K D of particular complexes to the overall K D value [12].…”

“…Fractions of different osmium(IV) complexes in the initial aqueous solution and their experimental (K D calc ) partition coefficients in the system tributyl phosphate-6 M hydrochloric acid[12] Table 4. Effect of hydrochloric acid concentration on the fraction of complex forms of Ir(IV) in hydrochloric acid solutions…”