Recovery of palladium(II) and rhodium(III) chloride complexes with a complexing S,N-containing sorbent

Abstract

Specifi c features of sorption recovery of palladium(II) and rhodium(III) chloride complexes from hydrochloric acid and chloride solutions with MITKhAT S,N-containing sorbent were revealed. The kinetic and capacity characteristics of the sorbent were determined in relation to the solution composition and kind of the metal. The most probable mechanism of sorption recovery and the composition of the forming Pd(II) and Rh(III) complexes were suggested. N S S The development of simple and quick methods for determination of platinum metals (PMs) in various objects is still a topical problem. Sorption-spectroscopic methods based on the use of complexing sorption materials, which are being actively developed now, are successfully used for this purpose [1][2][3][4].To improve procedures for sorption preconcentration of PMs, it is extremely important to know the composition and structure of the complexes formed by interaction of platinum metals with functional groups of the sorbents as polymeric ligands and to understand the effect exerted by the polymeric matrix of the sorbents on their kinetic and capacity characteristics [5][6][7]. The most widely used sorption materials for preconcentration and recovery of platinum metals from solutions are those containing sulfur and sulfur + nitrogen.The sorbents used can be subdivided into inorganic [4,8], including silica gels with complexing groups grafted to the matrix [9], and organic, based on an organic polymeric matrix and modifi ed with various compounds bearing S,N-and S-containing functional groups [5][6][7]10]. A particular place is occupied by sorbents whose donor atoms are components of the matrix itself. The amount of sorption sites in such sorbents is considerably higher than the amount of the possible grafted groups [4,[11][12][13][14][15]. Among such sorption materials, we should note heterochain sorbents of polycondensation type, formed by condensation of formaldehyde with hydrogen sulfi de and by thiomethylation of polyamines [13,[16][17][18][19].This study deals with revealing specifi c features of the sorption recovery of palladium(II) and rhodium(III) chloride complexes from hydrochloric acid and chloride solutions with a heterochain S,N-containing low-molecular-weight oligomer, MITKhAT [17][18][19].The sorbent, a white crystalline powder (mp 64-65°С and molecular weight 135), contains approximately 12 wt % N and 47 wt % S. It contains a tertiary nitrogen atom and alternating methylene and methylene sulfi de