Transport of different microplastics in porous media: Effect of the adhesion of surfactants on microplastics

The adhesion of surfactant molecules on the microplastics surface is affected by the surface structure of the microplastics. Little is known about the mobility of different microplastics in the medium under surfactants. In order to reveal the migration of different microplastics under the action of surfactants, the study selected five kinds of microplastics (polyethylene (PE), polypropylene (PP), polystyrene (PS), polytetrafluoroethylene (PTFE), polymethyl methacrylate (PMMA)) and two kinds of surfactants (cetyltrimethylammonium bromide, CTAB and sodium dodecyl benzene sulfonate, SDBS) as the research objects. The column experiment was used to explore the transport behavior of microplastics under different concentrations of surfactants and the convection dispersion model was used to simulate. The dynamic contact angle of the surfactant solution on the microplastics was measured and the adhesion work was calculated by the Young-Dupre equation to reveal the underlying mechanism of microplastics retention in the presence of surfactants. The results showed that the transport ability of microplastics followed the order of PTFE