Grafted membrane

Gubler, L., S. A. Giirsel, and G. G. Scherer, Radiation-grafted membranes for polymer electrolyte fuel cells. Journal Fuel Cells, August 2005. 

Hatanaka, T., Hasegawa, N., Kamiya, A., Kawasumi, M., Morimoto, Y. and Kawahara, K. 2002. Cell performances of direct methanol fuel cells with grafted membranes. Fuel 81 2173-2176. 

Nezu, S., Seko, H., Gondo, M. and Ito, N. 1996. High performance radiation-grafted membranes and electrodes for polymer electrolyte fuel cells. Department of Energy (DOE). Fuel cell seminar, Orlando. 

Patri, M., Hande, V. R., Phadnis, S. and Deb, P. C. 2004. Radiation-grafted solid polymer electrolyte membrane Studies of fluorinated ethylene propylene (PEP) copolymer-g-acrylic acid grafted membranes and their sulfonated derivatives. Polymers for Advanced Technologies 15 485-489. 

Novel responsive controlled release systems based upon polyelectrolyte-grafted membranes have also been reported. Iwata and Matsuda prepared novel environmentally sensitive membranes by grafting poly(acrylic acid) onto poly(vinylidene fluoride) membranes [382, 383]. Under basic conditions, the... 

Ultraviolet graft polymerization of arylamide onto cellulose acetate reverse osmosis membranes yielded grafted membranes with higher salt retention and lower water flux compared with pristine cellulose acetate [152]. Acid-catalyzed grafting of styrene on cellulose acetate reverse-osmosis membranes imparted a higher salt rejection rate (92.4%) to the membrane than those of ungrafted membranes (80.8%) and heat-shrunk membranes (90.2%) [153]. 

Ritchie SMC. Polymer grafted membranes. Membrane Science and Technology Series. 2003 8 299-327. 

A significant number of works are concerned with the development of new membranes for the separation of mixtures of aromatic/alicyclic hydrocarbons [10,11,77-109]. For example, the following works can be mentioned. A mixture of cellulose ester and polyphosphonate ester (50 wt%) was used for benzene/cyclohexane separation [113]. High values of the separation factor and flux were achieved (up to 2 kg/m h). In order to achieve better fluxes and separation factors the attention was shifted to the modification of polymers by grafting technique. Grafted membranes were made of polyvinylidene fluoride with 4-vinyl pyridine or acrylic acid by irradiation [83]. 2-Hydroxy-3-(diethyl-amino) propyl methacrylate-styrene copolymer membranes with cyanuric chloride were prepared, which exhibited a superior separation factor /3p= 190 for a feed aromatic component concentration of 20 wt%. Graft copolymer membranes based on 2-hydroxyethyl methylacrylate-methylacrylate with thickness 10 pm were prepared [85]. The membranes yielded a flux of 0.7 kg/m h (for feed with 50 wt% of benzene) and excellent selectivity. Benzene concentration in permeate was about 100 wt%. A membrane based on polyvinyl alcohol and polyallyl amine was prepared [87]. For a feed containing 10 wt% of benzene the blend membrane yielded a flux of 1-3 kg/m h and a separation factor of 62. 

Wang H, Tanaka K, Kita H, and Okamoto K. Pervaporation of aromatic/non-aromatic hydrocarbon mixtures through plasma-grafted membranes. J Membr Sci 1999 154 221-228. 

Decent performance curves in short-term operation have been reported for radiation-grafted membranes in DMFC (Figure 27.57). An advantage versus Nation has been observed by Geiger et al. and Scott et al. (for higher current densities) but so far, all-reported DMFC measurements have been performed for short operating times [115,116]. 

FIGURE 27.56 Diagram of the preparation process for radiation-grafted membranes. (Reproduced from Geiger, A.B., Rager, T., Matejek, L., Scherer, G.G., and Wokaun, A., in Proceedings of the 1st European PEFC Forum, Btichi, F.N., Scherer, G.G., and Wokaun A. (Eds.) 2001. With permission.)... 

J. Huslage, T. Rager, B. Schnyder, and A. Tsukada. Radiation-grafted membrane/electrode assemblies with improved interface. Electrochimica Acta 48, 247-254 2002. 

H.P. Brack, M. Wyler, G. Peter, and G.G. Scherer. A contact angle investigation of the surface properties of selected proton-conducting radiation-grafted membranes. Journal of Membrane Science 214, 1-19 2003. 

G.G. Scherer, F.N. Buchi, and B. Gupta. Radiation grafted membranes forpol3Tner electrolyte fuel-cells, exsitu and in situ characterization. Abstracts of Papers of the American Chemical Society, 205, 74—PMSE 1993. 

G.G. Scherer, E. Killer, and D. Grman. Radiation grafted membranes—some structural investigations in relation to their behavior in ion-exchange-membrane water electrolysis cells. International Journal of Hydrogen Energy, 17, 115-123 1992. 

This chapter deals with the transport of actinide ions across liquid membranes resulting in their recovery/separation from complex matrices. The transport behavior of lanthanides is also discussed in many places, which has chemical similarity with the trivalent actinides and are often used as their homologs. The transport behavior of actinides/lanthanides across other membranes such as ceramic/metallic and grafted membranes is also included. Table 31.1 gives a summary of the extractants discussed in this chapter. 

Although ELM technique is quite efficient essentially due to the thinness of the membrane, large-scale application of this technique is limited in view of the difficulties encountered in the demulsification step needed for the recovery of the trapped metal ion. On the other hand, promise of the SLM technique has been demonstrated in the lab scale experiments. Large-scale applications of SLM require additional work in the area of stability/reusability of the membranes. Apart from the selective extraction, there is a need to develop the membranes that are compatible with the diluent/solvent mixture with respect to physical properties such as surface tension and viscosity. In addition, chemical/radiation environment of the feed/strip solution to which these membranes are subjected over long duration is an area of particular concern. Additional stability can be obtained by developing chemically grafted membranes. 

The effect of polymer morphology on membrane structure and conductance has been shown recently. In Ref. 25 hydrogen-based graft-copolymer membranes were compared in terms of morphology and performance to random copolymer membranes with the same ion content. For the hydrated grafted membranes TEM micrographs revealed a picture of a continuous phase-separated network of water-filled channels with diameters of 5 nm. In contrast to that, the random copolymer membranes exhibit a reduced tendency toward microphase separation water is... 

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