Electrokinetic properties of silica-titania mixed oxide particles dispersed in aqueous solution of C.I. Direct Yellow 142 dye – effects of surfactant and electrolyte presence

The mixed $SiO_2$-$TiO_2$ oxide obtained by the pyrogenic method with the silica:titanium percentage ratio equal to 20:80 (ST80) was used in the experiments. The influence of azo dye C.I. Direct Yellow 142 (DY) adsorption at the mixed oxide-solution interface on the electrokinetic properties of solid particles was studied. To determine solid surface charge density and zeta potential of examined suspensions the potentiometric titration and Doppler laser electrophoresis techniques were applied. The changes in structure of electrical double layer formed on the mixed oxide surface in the dye presence were specified as a function of DY concentration, inorganic salt addition and surfactant introduction. The effects of surfactant type and its concentration were determined. Three surfactants of different ionic character (anionic SDS, cationic CTAB and nonionic Triton X-100) were used in measurements. The obtained electrokinetic characteristics of ST80 mixed oxide dispersed in aqueous solutions with various adsorbate compositions is essential for such suspensions stability.