Thermodynamic Foundations for the Use of Gypsum and Magnesia Stone for the Neutralization of Heavy Metal Ions

Abstract

The need to protect technogenic soils from contamination with heavy metal ions determines the relevance of the topic under study. The aim of the work is to thermodynamically substantiate the ability of gypsum and magnesia stone to neutralize heavy metal ions. Such properties of gypsum and magnesia stone can be called geoecological protection, and the substances themselves can be called mineral geoantidotes. The main method for substantiating geoecological protection properties is a thermodynamic assessment of the reactions of interaction between ions of heavy metals and mineral geoantidotes, as well as an assessment of the solubility product of substances formed during their interaction. As a result of the research, the values of changes in the Gibbs energy during the interaction of mineral geoantidotes and heavy metal ions have been determined; it has been shown that possible products of interaction reactions can be minerals similar to natural ones. Calculations have shown the possibility of reactions occurring under non-standard conditions (1 to 40°C). The experiments carried out made it possible to determine the geoecological protective capacity of gypsum and magnesia stone in non-standard conditions and showed the absence of dependence of the geoecological protective capacity on the ambient temperature in the range from 1 to 40°C. The materials of the article can be useful for the development of technological solutions to reduce harmful pollution by ions of heavy metals of technogenic soils using gypsum and magnesia stone.