Silica gel modified with Zincon as a sorbent for preconcentration or elimination of trace metals

Abstract

The sorption of 14 metal species (Na, K, Mg, Ca, Al, Zn, Cu, Cd, Pb, Mn, Fe^III, Co, Ni and Cr^III) on silica gel, impregnated with a mixture of Zincon and Aliquat 336, was investigated. The relative capacities of the sorbent toward the metal ions were determined in the pH range 1–9, as were the concentrations of HCl and HClO₄ required for elution of the retained metals. Alkali metal ions were not retained on the sorbent; Mg²⁺ were retained from solutions at pH > 8, contrary to other metals ions. All the retained metals could be eluted with dilute solutions of HClO₄ without elution of the chelating agent from the sorbent. The sorbent was used for the preconcentration of trace amounts of some metals from aqueous solution before their determination by atomic absorption spectrometry, for the separation of metal ion mixtures by column-extraction chromatography, and for additional purification of some salt solutions from trace amounts of Zn, Pb, Cd and Cu. The effectiveness of purification was confirmed by anodic stripping voltammetry.