(129b) Research Into Molecular Separations Using Osn At Imperial College

Organic liquids are ubiquitous in chemical science based industries, which range in scale from refining to pharmaceutical production. It is generally accepted that 40-70% of capital and operating costs in these industries are dedicated to separations; and a substantial fraction of this cost is related to processing of organic liquids, both as product streams and solvents. Membrane technology has the potential to provide game changing alternatives to conventional concentration and purification technologies such as distillation, liquid extraction, adsorption and chromatography. In order to achieve this potential, membrane modules must meet several challenges. They must be stable in organic solvents, offer attractive fluxes and rejections for systems of interest, and give reliable and predictable service lifetime and performance. The obvious benefits of membrane processing have been apparent for many years, and have attracted research, development and commercialisation efforts from academic groups, end users, and membrane suppliers. In the last few years these efforts have resulted in Organic Solvent Nanofiltration (OSN) emerging as a new membrane technology.

This presentation will describe some key research activities in the Livingston group at Imperial College London into OSN. These include formation and function of OSN membranes, imaging and characterisation of these membranes, simulation and process design of OSN systems, and applications of OSN in organic processes. Several polymers (polyimides, polybenzimidazole, PEEK) have been used to create membranes stable in organic solvents. A key step is the post-formation chemical crosslinking of the polymers, which imparts stability even in harsh polar solvents such as DMF, THF and DMSO. Recently developed membranes include thin film composites based on interfacial polymerisation (TFC-IP). By using inert supports, TFC-IP membranes having good flux and rejection in polar aprotic solvents have been developed. A further innovation is the development of OSN membranes that can withstand highly basic and acidic environments, which further widens the scope of the technology.

OSN membranes have permeation pathways in the nanometre range and so are hard to characterise. On-going work using contrast agents and high resolution TEM is yielding some interesting insights into membrane structure. Simulation and process design allied to validation using spiral wound module data allows the prediction of process performance. There are a growing number of applications of OSN to industrial separation problems, and two main areas will be highlighted, the purification of pharmaceutical API, and the formation of peptides and oligonucleotides using OSN technology.