Effect of solute concentration and mass transfer limitations on transport in organic solvent nanofiltration — partially rejected solute

This work examines flux and rejection performances under cross-flow for several concentrated (5–30 wt.%) methanol–dimethyl methylsuccinate (DMMS) solutions permeating through two commercially available organic solvent resistant nanofiltration membranes (Starmem™ 122 (S-122) and MPF-50). The experimental flux/rejection data for the flat sheet membranes was fitted using pore-flow and solution-diffusion models for membrane transport, coupled with film theory for liquid mass transfer effects. It was found that solution-diffusion gives a better description of some of the experimental trends. In the practical range of concentrations studied, rejection should be seen as a variable, dependent on the mass transfer characteristics of the nanofiltration system in use.