Phosphonic acid membranes

Poly(acrylonitrile-co-vinyl phosphonic acid) membrane... 

Figure 5.2 compares the change in PNaCa of a phosphonic acid membrane and that of a sulfonic acid membrane with the concentration of the mixed salt solution when 1 1 mixed salt solutions composed of calcium chloride and sodium chloride of various concentrations were electrodialyzed.26 PNaCa of the phosphonic acid membrane is lower than that of the sulfonic acid membrane. Transport numbers of all alkaline earth metal cations relative to sodium ions for the phosphonic acid membrane are also lower than those of the sulfonic acid membrane.26 However, the current efficiency of the phosphonic acid membrane was about 10% lower than that of the sulfonic acid membrane. Alkaline earth metal cations more... 

Figure 5.2 Comparison of transport number of calcium ions relative to sodium ions in a phosphonic acid membrane with that in a sulfonic acid membrane. ( ) sulfonic acid membrane (A) phosphonic acid membrane. 1 1 mixed salt solutions of calcium chloride and sodium chloride of different concentrations were electrodialyzed.

Figure 53 Ion exchange equilibrium constants of alkaline earth metal cations relative to sodium ions in sulfonic acid and phosphonic acid membranes. (O) sulfonic acid membrane (O) phosphonic acid membrane. Membranes were equilibrated with a 1 1 mixed solution of 0.250 N alkaline earth metal cation and 0.250 N sodium chloride (concentration of chloride ions 0.500 N).

Figure 5.4 Electrical resistance of sulfonic acid and phosphonic acid membranes measured in 0.500N alkaline earth metal chloride solution. (O) sulfonic acid membrane (A) phosphonic acid membrane. Electrical resistance was measured with 1000 Hz ac at 25.0 °C after the membrane had been equilibrated with a 0.500N alkaline earth metal chloride solution.

Schmidt-Naake, G., Bohme, M. and Cabrera, A. 2005. Synthesis of proton exchange membranes with pendent phosphonic acid groups by irradiation grafting of VBC. Chemical Engineering and Technology 28 720-724. 

Li, S., Zhou, Z., Abernathy, H., Liu, M., Li, W, Ukai, J., Hase, K. and Nakanishii, M. 2006. Synthesis and properties of phosphonic acid-grafted hybrid inorganic-organic polymer membranes. Journal of Materials Chemistry 16 858-864. 

Functionalized polymers are of interest in a variety of applications including but not limited to fire retardants, selective sorption resins, chromatography media, controlled release devices and phase transfer catalysts. This research has been conducted in an effort to functionalize a polymer with a variety of different reactive sites for use in membrane applications. These membranes are to be used for the specific separation and removal of metal ions of interest. A porous support was used to obtain membranes of a specified thickness with the desired mechanical stability. The monomer employed in this study was vinylbenzyl chloride, and it was lightly crosslinked with divinylbenzene in a photopolymerization. Specific ligands incorporated into the membrane film include dimethyl phosphonate esters, isopropyl phosphonate esters, phosphonic acid, and triethyl ammonium chloride groups. Most of the functionalization reactions were conducted with the solid membrane and liquid reactants, however, the vinylbenzyl chloride monomer was transformed to vinylbenzyl triethyl ammonium chloride prior to polymerization in some cases. The reaction conditions and analysis tools for uniformly derivatizing the crosslinked vinylbenzyl chloride / divinyl benzene films are presented in detail. 

Subramanian and coworkers developed polymeric sorbents using different support materials (such as Merrifield chloromethylated resin, Amberlite XAD 16) and complexing ligands (amides, phosphonic acids, TTA), and evaluated their binding affinity for U(VI) over other diverse ions, even under high acidities. The practical utility of these sorbents was demonstrated using simulated waste solutions (220-222). Shamsipur et al. reported the solid-phase extraction of ultra trace U(VI) in natural waters using octadecyl silica membrane disks modified by TOPO (223). The method was found satisfactory for the extraction and determination of uranium from different water samples. 

Fig. 13.27. Potential vs. current density plots for state-of-the-art fuel cells, o, proton exchange membrane fuel cell , solid oxide fuel cell , pressurized phosphonic acid fuel cell (PAFC) a, direct methanol fuel cell, direct methanol PAFC , alkaline fuel cell. (Reprinted from M. A. Parthasarathy, S. Srinivasan, and A. J. Appleby, Electrode Kinetics of Oxygen Reduction at Carbon-Supported and Un-supported Platinum Microcrystal-lite/Nafion Interfaces, J. Electroanalytical Chem. 339 101-121, copyright 1992, p. 103, Fig. 1, with permission from Elsevier Science.)...

Not many publications report performance data with BAM s membranes. The only publication we are aware of is by Stone et al., which also discusses the possibility of introducing a phosphonic acid functionality [98]. Figure 27.55 shows the performance data from this source. 

C. Stone, T.S. Daynard, L.Q. Hu, C. Mah, and A.E. Steck. Phosphonic acid functionalized proton exchange membranes for PEM fuel cells. Journal of New Materials for Electrochemical Systems 3, 43-50 2000. 

Nakamura, S., Ohashi, S., and Akiba, K., Transport of uranium(VI) through a liquid membrane impregnated with phosphonic acid ester. Buns. Kagaku Jpn. Anal, 1991, 40 829-834. 

Kubota F., Goto M., and Nakashio F., Extraction kinetics of rare earth metals by 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester using a hollow fiber membrane extractor. Sep. Sci. Technol. 30, 111, 1995. 

To prepare new and inexpensive membranes, various trials have been made 196 sulfonated aromatic polyether membrane such as polyether ketones (PEEK),197 sulfonated polysulfone198 and membranes from sulfonated polyphenylene sulfide,199 phosphoric acid-doped polybenzimidazole, (PBI),200 polybenzimidazole having sulfonic acid groups,201 polybenzimidazole with phosphonic acid groups,202 a blend membrane of polybenzimidazole and sulfonated polysulfone,203 sulfonated phosphazene polymer.204... 

T. Sata, T. Yoshida and K. Matsusaki, Transport properties of phosphonic acid and sulfonic acid cation exchange membranes,./ Membr. Sci., 1996,120, 101-110. 

N. Pismenskaya, E. Laktionov, V. Nikonenko, A.E1 Attar, B. Auclair and G. Pourcelly, Dependence of composition of anion-exchange membranes and their electrical resistance on concentration of sodium salts of carbonic and phosphonic acids, J. Membr. Sci., 2001, 181, 185-197. 

D.K. Hale and K.P. Govindan, Bi-ionic potentials with sulfonic and phosphonic acid cation-exchange membranes,./ Electrochem. Soc., 1969, 116, 1373-1381. 

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