APPLICATION OF ADSORPTION MODELS FOR DESCRIPTION OF GOLD SORPTION FROM CHLORIDE SOLUTIONS BY NATURAL ZEOLITES IN A STATIC MODE

Abstract

Comparative analysis of natural zeolites sorption properties of the Yagodninskoe deposit of mordenite-clinop-tylolite type in Kamchatka Territory and the Seredochnoe deposit of geylandite-clinoptylite type in Khabarovsk Krai in relation to chloride solutions of gold in the concentration range from 2.0 to 10.0 mg/l is carried out experimentally. The values of the ultimate sorption capacity of zeolites and the adsorption equilibrium constants are determined using the Langmuir equation. The values of Gibbs free energy are calculated, which allow to conclude about the spontaneous sorption process of gold chloride complexes from weakly acidic solutions. The Gibbs energy values are: ΔG = -28.3 kJ/mol and ΔG = -26.2 kJ/mol for zeolite tuffs of Yagodninskoe and Seredochnoe deposits, respectively. Empirical Freundlich’s equation coefficients k’ equalling 2.1∙10 -3 and 5.2∙10 -3 and degree indexes n equalling 3.66 and 2.26 are determined for zeolites from Yagodninskoe and Seredochnoe deposits respectively. Experimental data analysis with the help of the Dubinin-Radushkevich model shows that the sorption mechanisms differ depending on the initial gold concentration and degree of surface coverage. In the concentration range from 2.0 to 6.0 mg/l the ion-exchange mechanism prevails, and in the concentration range from 6.0 to 10.0 mg/l the mechanism of physical-chemical sorption prevails. The results obtained show that natural zeolites can be used as effective sorbents for gold recovery from drainage water generated during the storage of cakes from gold leaching plants.