Performance of a DOW BW30 RO membrane for the separation of nopinone from methanol-water solvent

Reverse osmosis (RO) membrane technology represents a low-cost, low-energy alternative for the separation of multi-component organic mixtures. However, limited availability of experimental data renders the design of such systems challenging. Moreover, mixtures containing multiple solvent species complicate the applicability of common membrane transport models. This study presents experimental data on the dead-end batch separation of nopinone, a useful intermediate in the chemical industry, from mixed methanol-water solvent across a DOW BW30 RO membrane. Membrane rejection and flux values were determined for feed concentrations of 0.449 – 1.099 M. Data analysis via the solution-diffusion model revealed the presence of convective transport in the investigated system, while the Spiegler- Kedem model obtained a reasonable system description when using a single coefficient for mass transfer description. Accurate calculation of osmotic pressure in the mixed-solvent system was found to impact data analysis due to the effects of non-ideality on the transmembrane driving force. From the Spiegler-Kedem model, permeability coefficient values A and B were yielded of order 10-7 and 10-8, respectively, with a membrane selectivity of ~30 bar-1. Finally, the system’s separation performance in continuous cross-flow was estimated by considering a series of dead-end batch separation units, suggesting feasible system operation at industrial scale.