Experimental results on the nanofiltration (NF) separation behavior of three different solvent- compatible membranes are presented for three organic solutes of molecular weights 351, 826 and 1355 in methanol; the manufacturer-specified molecular weight cut-offs (MWCO) of the membranes are 250, 400 and 700. Membranes were primarily tested at 440 psig, at different concentrations of the solutes in methanol; the effect of varying the applied pressure was also briefly explored. The solvent permeation flux and the solute rejection were time dependent for an extended initial period; the membranes had to be compacted to achieve steady-state results. Furthermore, the manufacturer-specified MWCO was found to be an insufficient indicator of the separation capabilities of the membranes.

Organic syntheses which involve species of diverse molecular weights and dimensions, such as those found in the pharmaceutical industry, could benefit from the availability of solvent-compatible NF membranes. A mathematical model was developed to illustrate the effects of external coupling of the operation of a batch/semibatch reactor with a NF unit, A hypothetical reaction system consisting of two parallel reactions was considered. Numerical simulations of the governing equations with realistic parameters, showed that the reaction conversion, selectivity and final product concentration could be improved considerably via this external reactor-membrane separator coupling.