Organic solvent nanofiltration membranes

ORGANIC SOLVENT NANOFILTRATION MEMBRANES 455 TABLE 16.3 Commercially Available Soluble Polyimides"... 

ORGANIC SOLVENT NANOFILTRATION MEMBRANES 457 TABLE 16.4 Literature OSN Performance Data... 

Organic solvent nanofiltration membranes can be used in the separation of petroleum fractions, recovery of components from petroleum streams, or fuel upgrading. Ohya et al. (1997) prepared a series of asymmetric PI membranes, and using ones with an MWCO of 170 Da succeeded in separating gasoUne-kerosine mixtures, with a... 

Peyravi, M., Rahimpour, A., and Jahanshahi, M. 2012. Thin film composite membranes with modified polysulfone supports for organic solvent nanofiltration. Journal of Membrane Science 423 24 225-237. 

Solomon, M. F. J., Bhole, Y, and Livingston, A. G. 2012. High flux membranes for organic solvent nanofiltration (OSN)—Interfacial polymerization with solvent activation. Journal of Membrane Science 423-424 371-382. 

White L. S. 2006. Development of large-scale applications in organic solvent nanofiltration and pervaporation for chemical and refining processes. Journal of Membrane Science 286 26-35. 

Use of nanofiltration for non-aqueous separations is limited by membrane compatibility - a common material in composite nanofiltration membranes used for aqueous separations is polysulfone which possesses limited solvent resistance [134]. However, during the past two decades a number of materials have emerged with improved solvent resistance that have enabled a broad range of organic solvent nanofiltration (OSN) applications. These materials include polydimethylsiloxane, polyphenylene oxide, polyacrylic acid, polyimides, polyurethanes, and a limited number of ceramics. Commercial products are offered by Koch Membrane Systems, W.R. Grace, SolSep, and Hermsdorfer Institut fur Technische Keramik (HITK) [135]. 

Soroko, I. and Livingston, A. 2009. Impact of TiOj nanoparticles on morphology and performance of crosslinked polyimide organic solvent nanofiltration (OSN) membranes.. 7. Memh. Sci. 343(1-2) 189-198. 

The material science of long-term membrane compaction in asymmetric membranes is not well reported. This phenomenon has been observed in gas separations including this report, but also in reverse osmosis [6] and organic solvent nanofiltration [38]. How to accurately predict multi-year performance in the field with short-term lab tests is a continuing challenge. 

In addition, the ability to work in a wide range of operative conditions is another key aspect for the development of advanced membranes. Chemical stability is of particular importance when the membrane interfaces are exposed to aggressive solvents, such as in several organic solvent nanofiltration (OSN) applications [21]. Resistance to fouling is also important in water filtration because this phenomenon can threaten the continuous operability of the membrane module [22]. In high-temperature (eg, precombustion CO2 capture from syngas [23] or polymer electrolyte membranes for fuel cells [24]) and high-pressure (eg, reverse osmosis and nanofiltration membranes for... 

M. Peyravi, M. Jahanshahi, A. Rahimpour, A. Javadi, S. Hajavi, Novel thin film nanocomposite membranes incorporated with functionalized Ti02 nanoparticles for organic solvent nanofiltration, Chemical Engineering Journal 241 (2014) 155-166. 

J. Campbell, R.P. Davies, D.C. Braddock, A.G. Livingston, Improving the permeance of hybrid polymer/metal-organic framework (MOF) membranes for organic solvent nanofiltration (OSN) - development of MOF thin films via interfacial synthesis, Journal of Materials Chemistry A 3 (2015) 9668-9674. 

Valadez-Blanoo, R., Ferreira, F.C., Jorge, R.F. Livingston, A.G. (2008) Amembranebioreactorfor biotransformations of hydrophobic molecules using organic solvent nanofiltration (OSN) membranes. Journal of Membrane Science, 317 (1-2), 50-64. 

Fig e 20.4 Scheme of the membrane gas separation, pervaporation and organic solvent nanofiltration. 

When ionic liquids are used as replacements for organic solvents in processes with nonvolatile products, downstream processing may become complicated. This may apply to many biotransformations in which the better selectivity of the biocatalyst is used to transform more complex molecules. In such cases, product isolation can be achieved by, for example, extraction with supercritical CO2 [50]. Recently, membrane processes such as pervaporation and nanofiltration have been used. The use of pervaporation for less volatile compounds such as phenylethanol has been reported by Crespo and co-workers [51]. We have developed a separation process based on nanofiltration [52, 53] which is especially well suited for isolation of nonvolatile compounds such as carbohydrates or charged compounds. It may also be used for easy recovery and/or purification of ionic liquids. 

Solvent resistant nanofiltration membranes are a much more recent evolution. Historically, the membranes developed by Membrane Products Kyriat Weizmann (Israel) - now Koch - (MPF 44, MPF 50, MPF 60) were the first nanofiltration membranes intended for application in organic solvents, although other membranes (e.g., PES and PA membranes) also have a limited solvent stability. The Koch membranes are based on PDMS, similarly to pervaporation membranes, although the level of crosslinking is quite different. 

A difficult problem that prevented the use of nanofiltration in organic solvents for a long time was the limited solvent stability of polymeric nanofiltration membranes, and the lack of ceramic nanofiltration membranes. For polymeric membranes, different problems occurred zero flux due to membrane collapse [54], infinite nonselective flux due to membrane swelling [54], membrane deterioration [55], poor separation quality [ 5 6], etc. I n an early study of four membranes thought to be solvent stable (N30F, NF-PES-10, MPF 44 and MPF 50), it was observed that three of these showed visible defects after ten days exposure to one or more organic solvents, and the characteristics of all four membranes changed notably after exposure to the solvents [15]. This implies that these membranes should be denoted as semi-solvent-stable instead of solvent stable. 

Due to recent advances in membrane development, nanofiltration membranes are nowadays increasingly used for applications in organic solvents [27, 58]. This narrows the gap between pervaporation and nanofiltration. It is even possible that the requirements for membrane structures completely overlap for the two processes whereas membrane stability becomes more important for nanofiltration membranes, the performance of pervaporation membranes could be improved by using an optimized (thinner) structure for the top layers. It might even be possible to use the same membranes in both applications. At this moment it is not possible to define which membrane structure is necessary for nanofiltration or for pervaporation, and which membrane is expected to have a good performance in nanofiltration, in pervaporation or in both. Whereas pervaporation membranes are dense, nanofiltration membranes... 

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