  Solute-surface interactions have garnered considerable interest in recent
years as a novel control mechanism for driving unique fluid dynamics and
particle transport with potential applications in fields such as biomedicine,
the development of microfluidic devices, and enhanced oil recovery. In this
study, we will discuss dispersion induced by the diffusioosmotic motion near a
charged wall in the presence of a solute concentration gradient. Here, we
introduce a plug of salt with a Gaussian distribution at the center of a
channel with no background flow. As the solute diffuses, the concentration
gradient drives a diffusioosmotic slip flow at the walls, which results in a
recirculating flow in the channel; this, in turn, drives an advective flux of
the solute concentration. This effect leads to cross-stream diffusion of the
solute, altering the effective diffusivity of the solute as it diffuses along
the channel. We derive theoretical predictions for the solute dynamics using a
multiple-timescale analysis to quantify the dispersion driven by the
solute-surface interactions. Furthermore, we derive a cross-sectionally
averaged concentration equation with an effective diffusivity analogous to that
from Taylor dispersion. In addition, we use numerical simulations to validate
our theoretical predictions.
