(385r) Membrane Technologies: From Fundamental Transport to Techno-Economic Assessment

Organic mixture separation technologies such as pervaporation, organic solvent nanofiltration (OSN), and organic solvent reverse osmosis (OSRO) have witnessed increasing interest as valuable options for solvent recovery and purification, crude oil fractionation, and valuable solute and biochemical concentration after successful application in water desalination. In particular, OSRO could achieve finer separation of small molecules under the influence of a high-pressure system to drive specific molecules across the membrane, determined by their solubility and mobility, such as in polyethylene terephthalate production using high-purity p-xylene.

Whilst conventional techniques for specialty chemical separations in industry are energy-intensive, OSRO could serve as low-energy alternatives or complements to these incumbent technologies. This advantage is further realized in the separation of compounds that have low vapor pressures, which are difficult to separate using traditional phase change techniques. We show that careful experimental measurement of fundamental membrane transport properties (diffusion, sorption, and permeation), when combined with mathematical modeling, enables prediction of membrane separation performance under a wide variety of operating conditions.

By corroborating these fundamental and technological assessments with economic performance indicators, we highlight membrane technologies as industrially scalable, low-cost alternatives or supplements to silicone fluid purification and other challenging organic mixture separations. For instance, in xylene isomer purification, membrane cascade systems comprising pervaporation and OSRO modules demonstrate a cost savings of >50% compared to state-of-the-art Parex technology. This demonstrates the commercial attractiveness of membrane systems for small-molecule solvent separation.