Nanofiltration solvent-resistant membranes

TABLE 4.2. Commercially available solvent resistant nanofiltration membranes... 

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. 

Table 3.2 Commercial solvent-resistant nanofiltration membranes with characteristics as specified by the manufacturers.

For relatively porous nanofiltration membranes, simple pore flow models based on convective flow will be adapted to incorporate the influence of the parameters mentioned above. The Hagen-Poiseuille model and the Jonsson and Boesen model, which are commonly used for aqueous systems permeating through porous media, such as microfiltration and ultrafiltration membranes, take no interaction parameters into account, and the viscosity as the only solvent parameter. It is expected that these equations will be insufficient to describe the performance of solvent resistant nanofiltration membranes. Machado et al. [62] developed a resistance-in-series model based on convective transport of the solvent for the permeation of pure solvents and solvent mixtures ... 

A new approach is the application of chemometrics (and neural networks) in modeling [73]. This should allow identification of the parameters of influence in solvent-resistant nanofiltration, which may help in further development of equations. Development of a more systematic model for description and prediction of solute transport in nonaqueous nanofiltration, which is applicable on a wide range of membranes, solvents and solutes, is the next step to be taken. The Maxwell-Stefan approach [74] is one of the most direct methods to attain this. 

Solvent-resistant nanofiltration and pervaporation are undoubtedly the membrane processes needed for a totally new approach in the chemical process industry, the pharmaceutical industry and similar industrial activities. This is generally referred to as process intensification and should allow energy savings, safer production, improved cost efficiency, and allow new separations to be carried out. 

Problems to be solved are related to membrane stability (of polymeric membranes, but also the development of hydrophobic ceramic nanofiltration membranes and pervaporation membranes resistant to extreme conditions), to a lack of fundamental knowledge on transport mechanisms and models, and to the need for simulation tools to be able to predict the performance of solvent-resistant nanofiltration and pervaporation in a process environment. This will require an investment in basic and applied research, but will generate a breakthrough in important societal issues such as energy consumption, global warming and the development of a sustainable chemical industry. 

The reaction takes place in a continuously stirred tank reactor, thus reaching the activity and selectivity found in homogeneous reactions. The liquid is contacted with a nanofiltration (NF)-membrane that allows products to permeate but rejects the dissolved catalyst. This set-up is made possible by the development of solvent resistant NF-membranes having a molecular weight cut-off (MWCO) in the range 200-700 Da and working conditions below 40 °C and 35 bar. 

In catalytic Pd(0) reactions, this phosphonium salt was treated with a Pd(ll) source, base, and substrates to form an active catalyst for Sonogashira, Suzuki, and Heck coupling chemistry (Eq. 42, Eq. 43, Eq. 44). The reactions used 0.5 mol% of the Pd catalyst, >99.9% of which was recovered based on Pd analysis of the filtrate of a nanofiltration using UV-visible and total reflection X-ray fluorescence analysis. The spectroscopic analyses reportedly could detect as little as 0.05% of the 0.01 mmol of starting Pd catalyst in the leachate. The membrane used in this chemistry was a solvent-resistant nanofiltration membrane consisting of a porous poly(acrylonitrile) layer and a dense surface layer of poly(dimethylsiloxane). This membrane worked through nine cycles in the... 

Catalyst separation from reaction mixtures has been efficiently carried out by using solvent-resistant nanofiltration membranes [75]. Following an alternative approach to solving this problem a quaternary ammonium salt has been immobilized on a soluble poly(ethylene glycol) polymer support. The supported catalyst thus obtained, soluble in solvents commonly used in PTC such as dichloromethane and acetonitrile, was used in a series of standard reactions under PTC conditions with comparable results to those obtained with traditional PTC catalysts [76]. Moreover, it compares favorably to other quaternary salts immobilized on insoluble polystyrene supports [77]. The catalyst can be easily recovered by precipitation with ethereal solvent and filtration and shows no appreciable loss of activity when recycled three times. 

Kosaraju, P. B. and Sirkar, K. K. 2008.InterfaciaUy polymerized thin film composite membranes on microporous polypropylene supports for solvent-resistant nanofiltration. Journal of Membrane Science 321 155-161. 

Darvishmanesh S, Buekenhoudt A, Degr vea J, and Van der Bruggen B. General model for prediction of solvent permeation throngh organic and inorganic solvent resistant nanofiltration membranes. 7. Membr. Sci. 2009 334 43-49. 

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]. 

D. Bhanushali and D. Bhattacharyya, Advances in Solvent-Resistant Nanofiltration Membranes - Experimental Observations and Applications, Ann. N.Y. Acad. Sci., 984 (2003) 159-177. 

Luthra, X. Yang, L.M. Freitas dos Santos, L. S. White, A.G. Livingston, Phase-transfer catalyst separation and reuse by solvent resistant nanofiltration membranes, Chem. Commun. (2000) 1468-1469. 

L.S. White, Transport properties of a polyimide solvent resistant nanofiltration membrane, J. Memhr. Sci. 205 (2002) 191-202. 

D. Bhanushali, S. Kloos, D. Battar-CHARYYA, Solute transport in solvent-resistant nanofiltration membranes for non-aqueous systems experimental results and the role of solute-solvent coupling, /. Memhr. Sci. 208 (2002) 343-359. 

L. S. White, "Transport Properties of a Polyimide Solvent-resistant Nanofiltration Membrane , J. Memb. Sci. 205, 191 (2002). 

Aerts, S., Vanhulsel, A., Buekenhoudt, A., Weyten, H., Kuypers, S., Che, H., Bryjak, M., Gevers, L.E.M., Vankelecom, I.F.J. and Jacobs, P.A. 2006. Plasma-treated PDMS-membranes in solvent resistant nanofiltration Characterization and study of transport mechanism. 

Li, X., Basko, M., Prez, F.D. and Vankelecom, F.J. 2008a. Multifunctional membranes for solvent resistant nanofiltration and pervaporation application based on segmented polymer networks. 16539-16545. 

Basu, S. Maes, M. Cano-Odena, A. Alaerts, L. De Vos, D.E. Vankelecom, I. F. J. Solvent resistant nanofiltration (SRNF) membranes based on metal-organic frameworks. J. Membrane /., 2009, 344,190-198. 

R. Ding, H. Zhang, Y. Li, J. Wang, B. Shi, H. Mao, J. Dang, J. Liu, Graphene oxide-embedded nanocomposite membrane for solvent resistant nanofiltration with enhanced rejection ability. Chemical Engineering Science 138 (2015) 227-238. 

XJ7 Li, SD. Feyter, D.J. Chen, S. Aldea, P. Vandezande, F.D. Prez, and I.F.J. Vankelecom, Solvent-resistant nanofiltration membranes based on multilayered polyelectrolyte complexes, Chemistry of Materials 20 (2008) 3876-3883. 

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