Adsorption of metallic ions from aqueous solution on surfactant aggregates: a molecular dynamics study

Metallic ion adsorption on surfactant aggregates were studied with Molecular dynamics simulations. Using ionic salts, such as lead sulfate (PbSO${}_4$) and aluminum sulfate [Al${}_2$(SO${}_4$)${}_3$], adsorption of lead and aluminum were investigated at different salt concentrations and different surfactant aggregates (micelles) sizes. The micelles were constructed with spherical shapes composed of sodium dodecyl sulfate (SDS) anionic surfactants. The electrostatic interactions between the positive ions and the negative SDS headgroups promote capture of the metal particles on the aggregate surface. Metal adsorption was analyzed in terms of radial density profiles, partial pair distribution functions and adsorption isotherms. It is showed that SDS micelles adsorb better lead than aluminum ions regardless of the size of the aggregates and salt concentrations.