Calcium ion effects on the water/oil interface in the presence of anionic surfactants

Publication date: Available online 20 April 2019Source: Colloids and Surfaces A: Physicochemical and Engineering AspectsAuthor(s): Enrico Riccardi, Thomas TichelkampAbstractThe influence of ion type at constant ionic strength on the surfactant layer present between a polar and a non-polar liquid has been investigated. The investigated systems are composed of sodium bis(2-ethylhexyl) sulfosuccinate (AOT), dodecane and brines with different electrolyte compositions. Parallel and coordinated sampling have been performed via molecular dynamics simulation and experiments. By varying the molar ratio between calcium and sodium ions at constant ionic strength, we determined the relative influence of the bivalent ion. In the present work, firstly, we provide an atomistic description via molecular dynamics (MD) simulations of the surfactant and electrolyte distributions in respect to the dodecane-water interface. Secondly, we report the interfacial tension (IFT) and the estimated Debye length based on the theory of the electric double layer, comparing the simulation results with a classical interface description.Graphical abstract

Source: Colloids and Surfaces A: Physicochemical and Engineering Aspects - April 22, 2019 Category: Chemistry Source Type: research