The effect of surfactants on electrokinetic potential of tracer particles and borosilicate glass revealed within the development of SZP technique

The surface zeta potential (SZP) technique is a promising method for investigating the electrokinetic properties of various macroscopic surfaces. However, there have been no attempts as yet to use the SZP technique in the presence of surfactants. In this work, we studied the effect of classical low-molecular surfactants (SDS, АОТ, Triton X-100, and CTAB) on the properties of tracer particles with different size: commercial polystyrene (PSN, 27.2 ± 0.1 nm), “blue” colloidal (BI-ZR5, 191 ± 1 nm), and hydrophilic SiO₂ particles (520 ± 12 nm) obtained by quartz evaporation under the action of a relativistic electron beam. The initial charge of all the particles was negative. Anionic surfactants (АОТ and SDS) exerted virtually no effect on ζ-potential up to the concentration of 10⁻³ M and decreased it by ca. 27% at the concentration of 10⁻² M. Nonionic oxyethylated Triton X-100 increased ζ-potential but did not recharge the particles. Cationic CTAB recharged the surface of all the particles already at the concentration of 10⁻⁵ M; at 10⁻² M ζ-potential reached 39–65 mV. The possibility of applying BI-ZR5 as the tracer particles to estimate the electrokinetic potential of the borosilicate glass substrate in the presence of CTAB was demonstrated.