Chemistry, Physics and Technology of Surface

ISSN 2518-1238 (Online), ISSN 2079-1704 (Print)

The purpose of this research article is to study the influence of additives of cationic surfactant - benzethonium chloride and the pH of the initial solutions from which suspensions were prepared on the electro-surface properties of titanium dioxide of rutile modification in its aqueous suspensions as well as to detect changes in the ratio between positively charged and negatively charged surface hydroxyl groups due to adsorption of surfactant molecules.

In this study, we used powdered rutile-form titanium dioxide (average particle diameter 0.23 µm and specific surface area 14.6 m²/g), the surface of which was modified with inorganic oxides (Al₂O₃, 4 %, and SiO₂, 2 %) and graft hydrocarbon chains in order to impart required optical properties and regulate of  hydrophobic–hydrophilic balance. Benzethonium chloride is an industrial surfactant that is widely used to regulate the colloidal and chemical properties of many disperse systems.

According to the results of the research, it has been found that additives of benzethonium chloride to aqueous suspensions of titanium dioxide have a significant effect upon its electro-surface properties. By using the 2-pK model of a double electric layer and a multistage model of surfactant adsorption on a solid surface, it has been found that the adsorption of benzethonium chloride molecules results in a decrease in the number of surface neutral hydroxyl groups and in the redistribution of superficial positive and negatively charged hydroxyl groups. The character of the redistribution of these groups depends on the pH of the aqueous solutions on the basis of which the suspensions of titanium dioxide were prepared. By evaluating the effect of adsorption of benzethonium molecules on the electro-surface properties of titanium dioxide in its aqueous suspensions, three sites of their dependence on the pH of the initial solutions can be distinguished: the first in the range from pH ≈ 2 to pH ≈ 5, the second in the range from pH ≈ 5 to pH ≈ 9 and the third in the range from pH ≈ 9 to pH ≈ 12. The dependence analysis of the adsorption of benzethonium chloride molecules on the pH of the initial solutions shows that adsorption increases slightly in the first section, does not show any significant fluctuations in the second one, and increases significantly in the third one due to an increase in the pH of the output solutions. The adsorption quantities of benzethonium chloride on titanium dioxide which have been theoretically predicted according to the proposed model, are in good agreement with the experimental results.

An increase in the concentration of benzethonium chloride in suspensions involves the displacement of the isoelectric point of the investigated suspensions of titanium dioxide into the alkaline region. The obtained results are in good agreement with the experimental results of the study of the dependence of the zeta potential of titanium dioxide suspensions on the concentration of benzethonium chloride.

 The found dependencies allow to purposefully regulate properties of aqueous suspensions of titanium dioxide for production of necessary technological compositions.

1. Farrokhpay S. A review of polymeric dispersant stabilization of titanium pigment. Adv. Colloid Interface Sci. 2009. 151(1–2): 24. https://doi.org/10.1016/j.cis.2009.07.004

2. Rusanov A.I. The development of the fundamental concepts of surface thermodynamics. Colloid Journal. 2012. 74(2): 136. https://doi.org/10.1134/S1061933X1202010X

3. Parks G.A. The isoelectric points of solid oxides, solid hydroxides, and hidroxo complex systems. Chem. Rev. 1965. 65(2): 177. https://doi.org/10.1021/cr60234a002

4. Rosen M.I., Kunjappu J.T. Surfactants and Interfacial Phenomena. (N.Y.: John Wiley & Sons., 2012). https://doi.org/10.1002/9781118228920

5. Holmberg K., Jönsson B., Kronberg B., Lindman B. Surfactants and Polymers in Aqueous Solution. (Chichester: John Wiley & Sons, Ltd., 2003).

6. Tadros T. Polymeric surfactants in disperse systems. Adv. Colloid Interface Sci. 2009. 147–148: 281. https://doi.org/10.1016/j.cis.2008.10.005

7. Paria S., Khilar K.C. A review on experimental studies of surfactant adsorption at the hydrophilic solid-water interface. Adv. Colloid Interface Sci. 2004. 110(3): 75. https://doi.org/10.1016/j.cis.2004.03.001

8. Atkin R., Craig V.S.J., Wanless E.J., Biggs S. Mechanism of cationic surfactant adsorption at the solid-aqueous interface. Adv. Colloid Interface Sci. 2003. 103(3): 219. https://doi.org/10.1016/S0001-8686(03)00002-2

9. Tishchenko Yu.V., Glazunova I.V., Filonenko Yu.Ya., Petukhova G.A. Quantitative characteristics of active sites on the surface of sorbents produced by the modification of kaolinite with chlorosilanes. Russ. J. Phys. Chem. A. 2007. 81(6): 978. https://doi.org/10.1134/S0036024407060246

10. Kuchek A.E., Gribanova E.V. The acid-base characteristics of the surface of α-Al₂O₃: Potentiometry and wetting methods. Russ. J. Phys. Chem. A. 2007. 81(3): 387. https://doi.org/10.1134/S0036024407030156

11. Lanin S.N., Vlasenko E.V., Kovaleva N.V., Zung F.T. The adsorption properties of titanium dioxide. Russ. J. Phys. Chem. A. 2008. 82(12): 2152. https://doi.org/10.1134/S0036024408120315

12. Kuz'micheva G.M., Savinkina E.V., Belogorokhova L.I., Mavrin B.N., Flid V.R., Yakovenko A.G., Belogorokhov A.I. The characteristics of the nanosized η-TiO₂ polymorph. Russ. J. Phys. Chem. A. 2011. 85(6): 1037. https://doi.org/10.1134/S0036024411060203

13. Golikova E.V., Chernoberezhsky Yu.M., Johanson O.M. On correlation of aggregate stability and integral electro-surface characteristics of oxide dispersions. Colloid J. 2000. 62(5): 596. [in Russian].

14. Volkova A.V., Ignat'eva Yu.A., Ermakova L.E. Electrosurface characteristics of bulk titanium dioxide in solutions of simple electrolytes. III. Effect of multiply charged cations on adsorption and electrokinetic parameters of TiO₂. Colloid J. 2011. 73(6): 753. https://doi.org/10.1134/S1061933X11060196

15. Volkova A.V., Ermakova L.E., Bogdanova N.F., Tarabukina E.A., Sidorova M.P. Electrosurface characteristics of titanium dioxide in solutions of simple electrolytes: I. Effect of nature of counterions on adsorption and electrokinetic parameters of TiO₂. Colloid J. 2010. 72(6): 743. https://doi.org/10.1134/S1061933X10060037

16. Bogdanova N.F., Ermakova L.E., Sidorova M.P. Electrosurface characteristics of titanium dioxide in solutions of simple electrolytes: II. Calculation of electrical double layer parameters of TiO₂ from adsorption and electrokinetic measurements. Colloid J. 2010. 72(6): 749. https://doi.org/10.1134/S1061933X10060049

17. Petryshyn R.S., Yaremko Z.M., Soltys M.N. Effects of surfactants and pH of medium on zeta potential and aggregation stability of titanium dioxide suspensions. Colloid J. 2010. 72(4): 517. https://doi.org/10.1134/S1061933X10040125

18. Chen Y., Li W., Zhang X. Adsorption behavior of carboxymethyl starch on titanium dioxide surfaces. Colloid J. 2011. 73(2): 267. https://doi.org/10.1134/S1061933X11020189

19. Lange K.R. Surfactants: A Practical Handbook. (Cincinnati: Hanser/Gardner Publications, 1999).

20. Dukhin S.S., Deriaguine B.V. Surface and Colloid Science: Electrokinetic Phenomena. (N.Y.: Plenum Press, 1974).

21. Zhebentyaev A.I. Spectrophotometric determination of decamethoxine with eosin. Izv. Vyssh. Uchebn. Zaved., Khim. Khim. Tekhnol. 1984. 27(4): 412. [in Russian].

22. Petryshyn R.S., Yaremko Z.M., Soltys M.M. Determination of the ionization constants for surface hydroxyl groups of modified titanium dioxide in its aqueous suspensions. Him. Fiz. Technol. Poverhni. 2013. 4(2): 165. [in Ukrainian].

23. Zhang R., Somasundaran P. Advances in adsorption of surfactants and their mixtures at solid/solution interfaces. Adv. Colloid Interface Sci. 2006. 123–126: 213. https://doi.org/10.1016/j.cis.2006.07.004