Abstract
Organopolymeric and organosilicon heterochain complex-forming sorbents containing aliphatic thioether or (and) weakly basic amino groups or the complex selective analytical groups are highly effective sorbents for selective recovery and concentration of noble metals. They are characterized by high values of distribution coefficients and sorption capacity for noble metals owing to high concentration of functional groups in the polymeric chain (Table 1, 2). The mechanism of sorption of some noble metals from hydrochloric (Pd (II), Pt (IV), Rh (III), Au(III)) and nitric (Pd (II), Ag (I)) solutions by heterochain sorbents of net, linear and cyclic structure is discussed. It was shown, that mechanism of the interaction of metals ions with functional groups of sorbents and the type of generated sorption complexes are defined by the nature of electron-donor atoms and the metal, by the structure of the functional groups and their state depending on the acidity of solution, by equilibrium of complexation and hydrolysis of complex metal forms in solution as well by the composition of solution. Selectivity and the rows of sorption affinity of S-; S,O- and S,N-containing sorbents are in agreement with the concept of hard and soft acids and bases.
Highlights
The sorption by complex-forming sorbents (CS) is a perspective hydrometallurgical method of concentration and separation of noble metals in industrial and analytical practice.[1−4] Among CS’s studied at the present time weakly basic anion-exchangers, CS’s with thioether and S,Ncontaining functional groups are the most selective toward noble metals
The present review summarizes results of the study of the mechanism of sorption of the row of noble metals from hydrochloric and nitric acid solutions by organopolymeric N-; S,O-; S-; S,N-containing heterochain complex-forming sorbents (HS)’s, synthesized and investigated at the Institute of Organic Chemistry (Ufa Scientific Center, Russian Academy of Sciences), as well as organosilicon HS - poly-[N, N ′-bis-(3silsesquioxanylpropyl)thiocarbamide] (PSTU-3)[5,7,8] synthesized and investigated at Irkutsk Institute of Organic Chemistry (Table 1,2)
Sorption of Pd(II) from nitric acid solutions by polymethylenemonothioether[18] The sorption and complex-forming properties of the known highly selective and effective polymethylenemonothioether toward platinum metals in hydrochloric acid solutions have been investigated, described and utilized for development of a series of hybrid methods of the analysis.[2−4] In connection with the need for recovery of Pd(II) from nitric solutions generated by the nuclear fuel cycle and processing of the wastage of electron technique, we have investigated an opportunity of the selective recovery and the mechanism of the sorption of Pd(II) by PMS from nitric solutions with consideration of the equilibrium of hydrolysis and complexation of Pd(II) in a solution
Summary
The sorption by complex-forming sorbents (CS) is a perspective hydrometallurgical method of concentration and separation of noble metals in industrial and analytical practice.[1−4] Among CS’s studied at the present time weakly basic anion-exchangers, CS’s with thioether and S,Ncontaining functional groups are the most selective toward noble metals. In efficiency of the recovery of noble metals may be achieved by the application of heterochain complex-forming sorbents (HS) Such sorbents are distinguished by higher sorption capacity and distribution coefficients for noble metals owing to a high concentration of functional groups in the sorbent mass[2−4] (Table 1,2). They provide an extensive class of organopolymeric compounds, which differ by the nature of electron-donor heteroatoms and their mutual arrangement as well by the general structure of the polymer, which may be linear, branched, net or cyclic.
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