Siberian Federal University

The effect of temperature on the adsorption kinetics of nickel(II) ions by zeolite with immobilized thiosemicarbazide has been studied. Within the framework of the diffusion models of Boyd and Morris-Weber, a quantitative approach was used for the primary distinction between external and internal diffusion limitation of adsorption. It is shown that the diffusion of ions through the solution membrane and diffusion in the zeolite grain contribute to the overall rate of the process, and adsorption proceeds in a mixed diffusion mode. The contribution of the chemical stage to the kinetics of the heterogeneous adsorption process was characterized in terms of the kinetic models of Lagergren, Ho, and McKay and Elovich. The most applicable for describing explored the processes is the pseudo-second order model. The model assumes that the rate of adsorption of nickel(II) ions is limited by a chemical reaction, which, in the case of the zeolites under consideration, is accompanied by the formation of chelate complexes (composition 1:1) due to the donor-acceptor interaction of metal ions with nitrogen and sulfur atoms of the thiosemicarbazide fragment. This type of interaction is typical both for materials functionalized with thiosemicarbazide and, in general, for organic adsorbents containing N- and S‑active groups