Title: Osmotic and diffusio-osmotic flow generation at high solute concentration. I. Mechanical approaches,
Abstract: In this paper, we explore various forms of osmotic transport in the regime of
high solute concentration. We consider both the osmosis across membranes and
diffusio-osmosis at solid interfaces, driven by solute concentration gradients.
We follow a mechanical point of view of osmotic transport, which allows us to
gain much insight into the local mechanical balance underlying osmosis. We
demonstrate in particular how the general expression of the osmotic pressure
for mixtures, as obtained classically from the thermodynamic framework, emerges
from the mechanical balance controlling non-equilibrium transport under solute
gradients. Expressions for the rejection coefficient of osmosis and the
diffusio-osmotic mobilities are accordingly obtained. These results generalize
existing ones in the dilute solute regime to mixtures with arbitrary
concentrations.