LAUSR

Abstract This manuscript provides an understanding of the emulsification mechanisms of a model alkane (dodecane) in concentrated aqueous sodium silicate solutions, for e.g. formulating alkane/geopolymer composites for varied applications. To this purpose, we assume that silicate oligomers stabilize the emulsion by positioning themselves at the interface between alkane/aqueous solution. Moreover, the addition of an alkyltrimethylammonium, which interacts with silicate oligomers, is assumed to favor their positioning at the interface to increase the stability of the emulsion by Pickering effect. First, we study the influence of sodium silicate and hydroxide concentrations with up to 6 mol⋅L-1 (NaOH and SiO2) on the interfacial tension (γ) between dodecane and water. Secondly, we study the effect of CetylTrimethyl Ammonium Bromide (CTAB) and DecylTrimethylAmmonium Bromide (DeTAB) on the interfacial tension and the stability of the emulsion. Adding CTAB surfactant leads to partial precipitation but significantly decreases the interfacial tension to less than 4 mN.m-1. These effects that are not observed with DeTAB. The precipitate corresponds to CTAB-silicates and seems to contribute to the stabilization of the water/dodecane system, presumably through Pickering effect. Moreover, emulsion stability is shown to be related to the condensation/decondensation state of silicate species.