KINETIC CHARACTERISTICS OF THE SORPTION PROCESS OF IONS LANTHANUM BY METALLURGICAL SLAG

Abstract

The patterns of sorption of lanthanum ions from model nitrate solutions by metallurgical slag were investigated. It was shown that slag is a rather effective sorbent of lanthanum ions. The kinetics of sorption of lanthanum ions from model nitrate solutions by granulated blast furnace slag Zaporozhstal was studied. Based on the processing of integral kinetic sorption curves by the equations of diffusion kinetics, it was found that the sorption process proceeds in a mixed diffuse mode. The use of chemical kinetics models has shown that the stage of the chemical interaction of lanthanum ions with the functional groups of the sorbent also contributes to the overall speed of the process. According to Giles’ classification, isotherms of adsorption of lanthanum ions by slag belong to L-type isotherms. To obtain quantitative characteristics of the sorption of lanthanum ions on slag, the experimental results were processed using the sorption models of Langmuir, Freindlich, and Dubinin – Radushkevich. It has been established that experimentally the isotherm of sorption of lanthanum from model nitrate solutions by slag is well described by all models in the same range of equilibrium concentrations. The obtained value ΔG0 sorb = -25.83 kJ/mol indicates a rather high affinityof the sorbent for the sorbate and the advisability of using granular slag for the extraction of lanthanum compounds from model nitrate solutions. Using the Dubinin-Radushkevich model, which indicates the nature of sorbate sorption on the sorbent, the average free sorption energy was calculated. Calculations showed that the value of the free energy of sorption E = 7.18-8.33 kJ/mol indicates the physical nature of the interaction of the sorbate with the sorbent.

Keywords

• сорбція
• шлак
• лантан
• промислові відходи
• кінетика сорбції
• ізотерми сорбції