Properties of chelating sorbents prepared by impregnation of LiChroprep RP-8 and LiChroprep RP-18 with ion pairs formed by Aliquat 336 and Nitroso-R-Salt

Abstract

Two new chelating sorbents for metal ions were prepared by the impregnation of chemically modified silicas LiChroprep RP-8 and RP-18 with ion pairs composed of the cation of Aliquat 336 and the anion of Nitroso-R-Salt. The sorbents were compared with analogous sorbents with a plain silica carrier containing the same ion pairs. A hypothetical molecular mechanism of binding this ion pair by the surfaces of the applied carriers is presented. A higher stability of the two sorbents in comparison with that of the plain silica chelating sorbent was demonstrated. The sorbents obtained were applied to chromatographic separations of some chosen mixtures of some metal ions (the recovery of the separated metals was in the range 97% Co²⁺–99.5% Ca²⁺) and for additional purification of aqueous solutions of alkali and alkaline earth metals from trace amounts of heavy metals (Zn, Cd, Pb and Cu). The effectiveness of purification was confirmed by anodic stripping voltammetry. The multiple use of the sorbents based on RP-8 and RP-18 in sorption–desorption processes of metal ions without deterioration of their sorption capacities was demonstrated.