Diffusiophoresis and diffusioosmosis in tandem: Two-dimensional particle motion in the presence of multiple electrolytes

We develop a model of time-dependent diffusiophoretic compaction of colloids in a two-dimensional pore due to the gradient of a multivalent solute in tandem with a diffusioosmotic slip-driven background flow field. The model is simulated for various surface charges and particle diffusivities. We also conduct experiments varying the initial ion combinations and total solute concentration. Our results indicate that diffusiophoretic compaction can be increased or decreased by manipulating electrolyte and total solute concentrations, wall charge, and particle diffusivity; each effect can modify the particle velocity, with varying strength, in unison or in opposition to the other effects.