The Hofmeister effect in zeta potentials of CTAB-stabilised toluene-in-water emulsions

In this paper, we describe an experimental verification of the hypothesis of ion-specificity in counterion co-adsorption for cetyltrimethylammonium bromide (CTAB) at toluene–water interface (Hofmeister effect). For this purpose, toluene-in-water emulsions stabilised with CTAB in the absence and presence of inorganic electrolytes (NaBr, NaNO3, NaF and NaClO4), were used. Zeta potential measurements of the emulsions confirm both charging of the interface with surface-active cetyltrimethylammonium cation (CTA+), and anion dependence of the zeta potential. Electrokinetic measurements as a probe of diffuse layer potential show little effect of interfacial ion-specificity.