Membrane by chemical

Excessive concentrations of nuisance dusts in the workroom air may seriously reduce visibility, may cause unpleasant deposits in the eyes, ears and nasal passages, or cause injury to the skin or mucous membranes by chemical or mechanical action per se or by the rigorous... 

Recently several groups have tried to improve the properties of anisotropic gas separation membranes by chemically modifying the surface selective layer. For example, Langsam at Air Products and Paul et al. at the University of Texas, Austin have treated films and membranes with dilute fluorine gas [66-71], In this treatment fluorine chemically reacts with the polymer structure. By careful... 

J. Hayashi, H. Mizuta, M. Yamamoto, K. Kusakabe and S. Morooka, Pore Size Control of Carbonized BPDA-pp ODA Polyimide Membrane by Chemical Vapor Deposition of Carbon, J. Membr. Sci. 124, 243 (1997). 

Li, Y.Y., Bae, S.D., Sakoda, A., Suzuki, M. (2001a), Formation of vapor grow carbon fibers with sulfuric catalyst precursors and nitrogen as carrier gas. Carbon, 39, 91-100. Li, Y.Y., Bae, S.D., Nomura, T., Sakoda, A. and Suzuki, M. (2001b), Preparation of Custom-Tailored Carbon Whisker Membrane by Chemical Vapor Deposition, in K. Kaneko (Ed.), Fundamentals of Adsorption, 7,279-286. 

G.Z. Cao, H.W. Brinkman, J. Meijerink, K.J. de Vries and A.J. Burggraaf, Pore narrowing and formation of ultra thin yttria-stabilised zirconia layers in ceramic membranes by chemical vapor deposition. /. Am. Cer. Soc., 76 (1993) 2201-2208. 

In many cases it is possible to remove the membrane by chemical means, recondition the porous support, and reform either the same type or a different type of dynamic membrane at the application site. This feature gives each module a long operating life. 

Multilayer perfluorocarboxylic and sulfonic acid membrane by chemical treatment... 

Then Araki et al. [37] synthesized the silica membrane by chemical vapour deposition method on alumina support. They used commercial Pt catalysts for WGS reaction. Increase in reaction temperature from 525 to 575 K increases the... 

Mukheijee D, Kulkami A, and Gill WN, Flux enhancement of reverse osmosis membranes by chemical surface modification, Journal of Membrane Science 1994,97, 231-249. 

Surface-active agents can be embedded in a nanofiber membrane by chemical functionalization, by postspinning modification, by physical adsorption, or by nanoparticle polymer composites. 

S. Patra, N. Munichandraiah, Insoluble poly(anthranilic acid) confined in nafion membrane by chemical and electrochemical polymerization of anthranilic acid, Synthetic Metals 2005,150, 285. 

If liquids are present in the gas separation process, a liquid film can increase the membrane resistance markedly. Liquids can also damage the membrane by chemical action or by swelling or softening. If water vapor is present in the gas streams, the dew point may be reached in the residue product and liquid condensed. Also, condensation of hydrocarbons must be avoided. 

Choi, H.-S., Ryu, C.-H., Hwang, G.-J. (2013). Obtention of Zr02-Si02 hydrogen permselective membrane by chemical vapor deposition method. Chemical Engineering Journal, 232, 302-309. 

T. Bashir, J. Naeem, M. Skrifvars, et al.. Synthesis of electro-active membranes by chemical vapor deposition (CVD) process, Polym. Adv. Technol. 25 (2014) 1501—1508. 

Another bio-inspired approach is to design polymersomes as enclosed reaction compartments for the development of nanoreactors, nanodevices, or artificial organelles, in which active compounds are not only protected from the environment, but also allowed to act in situ. For such function, membrane permeability is of crucial importance, since it allows the exchange of substrates/products with the environment of the pol)maersomes. Various methods have been reported to generate polymersomes with permeable membranes (i) polymers forming intrinsically porous membranes, (ii) polymer membranes that are permeable to ions as e.g. specific oxygen species, (iii) pore formation in pH responsive polymer membranes by chemical treatment, (iv) polymer membrane permeabilization by UV-irradiation, and (v) biopores or membrane proteins inserted into polymer membranes. ... 

Figure 19.13. SEM top view and TEM side view of a nan-equilibrium impregnation-reduction electrode. Deposition conditions 0.6 mM Pt(NH3)4Cl2,1 mM NaBHi, 40 minutes impregnation time, 2 hours reduction time, 50 C [3]. (Reprinted by permission of ECS— The Electrochemical Society, from Liu R, Her W-H, Fedkiw PS. In situ electrode formation on a Nafion membrane by chemical platinization.)...

Liu R, Her W-H, Fedkiw PS. In situ electrode formation on a Nafion membrane by chemical platinization. J Electrochem Soc 1992 139 15-23. 

Hayashi J, Mizuta H, Yamamoto M, Kusakabe K, Morooka S (1997) Pore size control of carbonized BPTA-pp ODA polyimide membrane by chemical vapor deposition of carbon. J Membr Sci 124 (2) 243-251... 

Barsema JN, Van Der Vegt NFA, Koops GH, Wessling M (2002) Carbon molecular sieve membranes prepared from porous fiber precursor. J Membr Sci 205 (1-2) 239-246 Soffer A, Azariah A, Amar A, Cohen H, Golub D, Saguee S, Tobias H (1997) Method of improving the selectivity of carbon membranes by chemical vapor deposition. US Patent... 

Hayashi J, Yamamoto M, Kusakabe K, Morooka S (1995) Simultaneous improvement of permeance and permselectivity of 3,3 ,4,4 -biphenyltetracarboxylic dianhydride-4,4 -oxyd-ianiline polyimide membrane by carbonization. Ind Eng Chem Res 34 (12) 4364-4370 Hayashi J, Mizuta H, Yamamoto M, Kusakabe K, Morooka S (1997) Pore size control of carbonized BPTA-pp ODA polyimide membrane by chemical vapor deposition of carbon. J Membr Sci 124 (2) 243-251... 

The most recent work comes from Cao et al in 2012 [51]. They developed a poly(methyl vinyl ether- /f-malic anhydride) (PMVMA) membrane by chemical grafting of ammonium groups to the polymer. The membrane was stable up to 150° and showed increasing ion conductivity from room temperature to 60 °C. Their peak power density of 155 mW cm was obtained at 35 °C and on H2/O2 and demonstrated a vast improvement over lower temperatures (and hence higher ohmic resistances) (Figure 2.15). 

C. Qiu, S. Qi, C.Y. Tang, Synthesis of high flux forward osmosis membranes by chemically crosslinked layer-by-layer polyelectrolytes, Journal of Membrane Science, 381 (2011)74-80. 

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