SOLVING ENVIRONMENTAL SAFETY PROBLEMS BY SORPTION EXTRACTION OF MERCURY(II), NICKEL(II), ZINC(II) AND COPPER(II) IONS FROM AQUEOUS SOLUTIONS AND MAN- MADE FORMATIONS

This review aims to summarize the latest and currently relevant information on the preva-lence of heavy metal pollution of water bodies, as well as to systematize the accumulated knowledge about the sorption treatment of wastewater from heavy metals in the ionic form of various origins. The literature data on mineral and carbonaceous sorbents for the extraction of mercury, nickel, copper and zinc, which are common wastewater pollutants, are summarized. The high efficiency of modified mineral sorbents for solving this problem is shown. Sorption capacity with respect to heavy metal ions is provided mainly by the presence of functional groups (nitrogen-, oxygen-and sulfur-containing) capable of chelation, complexation and electrostatic interaction. Modified min-eral sorbents are characterized by an increase in the efficiency of extracting heavy metal ions with increasing temperature. For natural minerals, a decrease in the efficiency of adsorption with in-creasing temperature is observed, which is typical for a physical process. Under conditions of co-existence in a solution of several heavy metals, the affinity of a particular ion for the sorbent de-pends on the charge number of the element, the radius of the ion, which determines the degree of its hydration, and also on the polarizability. The value of adsorption increases with an increase in the contact time of the phases (until equilibrium is reached), as well as with an increase in the dose of the sorbent. Mercury, nickel, copper, and zinc ions reduced after adsorption on a substrate with a developed specific surface can serve as a raw material for the production of catalysts for many chemical processes. The review can be in demand both among researchers in the field of chemical sciences and politicians, private entrepreneurs, ecologists and environmental specialists. The re-view can be useful when planning new research within the framework of the implementation of national environmental programs.