Membrane formation – structure – performance

Effect of support and film morphology on transport in composite membranes

Transport of water and solutes through polymeric films is fundamental to the separation capacity of modern composite membranes, which comprise a thin film overlaying a porous support. The morphology of the top coating film is often very rough and this has been implicated as a main cause for increased fouling propensity.

Diffusive transport through a rough film, partially obstructed by a porous support.
The resulting flux distributions are shown above, resulting from the roughness, pores, and their combined effect.

In an ongoing theoretical study, we have been looking at how the underlying support structure, namely pore size and porosity, combined with the surface roughness, conspire to dictate the ultimate transport properties of the composite, as well as the flux distribution over the membrane, which we believe to be strongly linked to deposition and fouling. Results indicate that high permeability may also imply high fouling potential, but points to possible avenues for tailoring composite structures that allow a compromise between the two.