Research of the kinetic regularities of calcium ions solid-phase concentration by natural sorbents

Abstract

The most common way to prevent slippy roads in winter is by using de-icing mixtures, which combine
salts and organic materials and thus have both chemical and mechanical effects. Such mixtures are
usually obtained through sorption saturation with various modifying components, most commonly sodium, potassium, calcium, and magnesium chlorides. The aim of this study is to determine the optimal conditions for the adsorption of calcium ions by natural sorbents in the Astrakhan Region, as well as to evaluate the approximations of chemical and diffusion models describing the kinetics of sorption concentration in order to create anti-icing mixtures.
The sorbents: marl, an opal mineral of marl type (silica clay), and clay, were obtained by the nonchemical
processing of natural raw materials of the Astrakhan region, extracted by open pit mining.
The kinetic analysis of the adsorption of calcium ions included evaluating the loss of sorbate at different
time intervals. The evaluation was performed by means of direct potentiometry using an ELIS-121Са
ion-selective electrode with regard to a silver chloride reference electrode EVL-1M3.1, taking into account
the background electrolyte. The effect of the medium on the adsorption process was studied using an ESK-10601/7 combination glass electrode. It was determined that the silica clay reaches maximum adsorption capacity for calcium ions at pH = 6.94, marl at pH = 5.61, and clay at pH = 6.45.
The analysis of the Са²⁺ ions adsorption isotherms at the studied temperatures allows us to determine
the nature of the process: it is endothermic on clay and marl, and exothermic on silica clay. Silica clay
has the maximum sorption capacity for Са²⁺ ions; for clay and marl these values are practically the same. To identify the sorbate interactions, the isosteric heats of adsorption of Са2+ions were calculated. The analysis of the nature of the changein the isosteric heats of adsorption at various values of the degree of filling of the sorbent indicates that the studied natural sorbents have heterogeneous surfaces with centres of varying degrees of activity.
The interpretation of the kinetics of adsorption of calcium ions on natural sorbents allows us to state
that the adsorption process of calcium ions proceeds in a mixed diffusion mode. Graphical determination and theoretical calculation of the constants of external and internal diffusion, the values of the Bio-Rad’s criterion, and the apparent activation energy lead to the conclusion that for marl and clay the internal diffusion has the strongest effect at the limiting stage, while for silica clay it is external diffusion. The chemical interaction of the sorbate ions with the surface of sorbents contributes to the overall rate of the process. This isconfirmed by the fact that the experimental data corresponds to the kinetic model proposed by Ho and McKay.
The quantitative characteristics of adsorption of calcium ions determined by the experiment allow us
to conclude that it is possible to use the studied sorbents as carriers for the production of friction de-icing
agents. The obtained de-icing systems become active due to the release of energy during the joint physicochemical interaction of carriers and calcium ions with the ice surface.

References
1. Lv J., Song Y., Jiang L., Wang J., American Chemical Society, 2014, Vol. 8(4), pp. 3152-3169. DOI:10.1021/nn406522n.
2. Farnam Y., Dick S., Wiese A., Davis J., Bentz D., & Weiss J., Cement and Concrete Composites, 2015, Vol. 64, pp. 1-15.
3. Alykov N.M., Syutova E.A., Ekologicheskie sistemy i pribory, 2007, No 8, pp. 46-48.
4. Syutova E.A., Alykov N.M., Ekologiya i promyshlennost' Rossii, 2012, No 2, pp. 47-51.
5. Gromalova V.O., Fedotov A.I., Zedgenizov V.G., Gergenov S.M., Vestnik Sibirskogo gosudarstvennogo
avtomobil'no-dorozhnogo universiteta, 2018, Vol. 15, No 1 (59), pp. 55-60.
6. Dzhigola L.A., Sadomtseva O.S., Shakirova V.V., Kargina K.V. et al., Izvestiya vysshikh
uchebnykh zavedenii. Seriya: Khimiya i khimicheskaya tekhnologiya, 2018, Vol. 61, No 9-10,
pp. 105-112.
7. Dzhigola L.A., Syutova E.A., Izvestiya vysshikh uchebnykh zavedenii. Seriya: Khimiya i khimicheskaya tekhnologiya, 2018, Vol. 61, No 9-10, pp. 98-104.
8. Sirotkina E.E., Novoselova L.Yu., Chemistry for Sustainable Development, 2005, Vol.
13, pp. 359-375.
9. Dudarev V.I., Irinchinova N.V., Filatova E.G., Izv. vuzov. Khimiya i khim. Tekhnologiya, 2017, Vol. 60, No 1, pp. 75 80.
10. Tataeva S.D., Ramazanov A.Sh., Magomedov K.E., Bakhmudova A.G. Journal of Analytical
Chemistry, 2014, Vol. 69(1), pp. 45-50.
11. Boid D.E., Adamson A.V., Maiers L.S., Khromatografiya, M., Izd-vo inostr. lit-ry, 1949, 333 p.
12. Ramazanov A.Sh., Esmail G.K., Vestnik Dagestanskogo gosudarstvennogo universiteta, 2014, Vol. 1, pp. 179-183.
13. Nizamova G.R., Galimova R.Z., Shaikhiev I.G., Vestnik tekhnologicheskogo universiteta, 2017, Vol. 20, No 11, pp. 142-148.
14. Kiekpaev M.A., Stroeva E.V., Vestnik OGU, 2006, No 5, pp. 35-39.
15. Pimneva L.A., Nesterova E.L., Vestnik omskogo universiteta, 2011, No 2, pp. 130-134.
16. Briling I.A., Fil'tratsiya v glinistykh porodakh, M., VIEMS, 1984, 61 p.
17. Bleza M.A., Figliolia N.M., Maroto A.J.G., Regazzoni A.E., J. of Colloid and Int. Sci., 1984, Vol. 101(2), pp. 410-418.
18. Makarov A.V., Diss. kand. tekhn. nauk, Tomsk, 2013, 154 p.
19. Hawari A., Rawajfih Z., Nsour N., J. Hazard. Mater., 2009, Vol. 168, pp. 1284-1289.
10. Alosmanov R.M., Vestn. Mosk. un-ta. Ser.2. Khimiya, 2011, Vol. 52, No 2, pp. 145-148.
21. Alykov N.M., Syutova E.A., Alykov E.N. Patent RF, No 2378311, 2007.