Cation-exchange resins porous

A divinylbenzene-ethylene-styrene copolymer is sulfonated by 3.5-10% solutions of chlorosulfonic acid in organic solvents, e.g. chloroform or 1,2-dichloroethane at RT to yield cation-exchange resins. Porous st)rrene-divinyl-benzene-ethylvinylbenzene copolymers have also been treated with the reagent and hydrazine hydrate to form ion-exchange resins containing sulfonyl hydrazide groups. ... 

Sensors based on the above reaction scheme have been developed for Al3+, Zn2+, Cu2+, Ca2+, Pb2+, Hg2"1", K+, Li+, etc. A polycation, protamine sensor has also been developed using 2/7/-dichlorofluorescein octadecyl ester (DCFOE) doped in polymer membranes. However, most of these sensors are pH dependent due to the pH dependence of the cation complexation reactions. The cation ion indicators can be immobilized on any solid support, such as silica, cellulose, ion-exchange resin, porous glass, sol-gel, or entrapped in polymer membranes. 

Large quantities of ion-exchange resin MSC-1, a strongly acidic macro-porous cation-exchange resin, or Duolite A-162, a strongly basic macroporous anion-exchange resin, were cleaned at one time. 

Figure 15-14 Solid colored circles show the drift in apparent pH of a low-conductivity industrial water supply measured continuously by a single electrode. Individual measurements with a freshly calibrated electrode (black circles) demonstrate that the pH is not drifting. Drift is attributed to slow clogging of the electrode s porous plug with AgCI(s). When a cation-exchange resin was placed inside the reference electrode near the porous plug, Ag(l) was bound by the resin and did not precipitate. This electrode gave the drift-free, continuous reading shown by open diamonds. [From S. Ho, H. Hachlya. K. Baba. Y. Asano. and H. Wada, Improvement of the Ag I AgCt Reference Electrode and Its Application to pH Measurement," talonta 1995,42.1685.]...

The esterification of acetic acid with ethanol has been investigated using zeolite membranes grown hydrothermally on the surface of a porous cylindrical alumina support (the catalyst used was a cation exchange resin) [37]. The conversion exceeded the equilibrium limit, by the selective removal through the membrane of water and reached to almost 100% within 8h [37]. 

The cation-exchange resins obtained from SDVB copolymers prepared by conventional pearl polymerization technique mostly have the gel structure. The conventional SDVB copolymer has been modified by using a solvent or a linear.polymer in the monomer mixture during the polymerization to make porous SDVB copolymers. 

Uziele/ al. (U5) used porous divinyl benzene cation-exchange resins to separate the four nucleoside hydrolysates of RNA. Burtis et al. (B34, B35) used a smaller particle cation-exchange material for this separation and also investigated the various parameters that affected the separations. 

Cationic exchange resins have been used as supports for FeCla. In esterification the catalytic activity of polymeric complexes prepared from porous type resins was much higher than that of complexes prepared from gel type resins [25]. 

Wheelwright has developed a cation exchange separation of americium from the lanthanides using DTPA as eluent (24). Nakamura et al. have improved the process by incorporating a porous-type cation-exchange resin and a pressurized column (25). The effect of radiation damage of the resin has been also investigated on operation modes. 

If chains of a cation exchange resin and chains of an anion exchange resin are captured in a porous polymer bead they tend to line up with their charges opposite to each other. A mixture of ions or polar compounds passing through the beads will be retarded. This ion retardation (Chapter 25) is an excellent way to separate ionic from nonionic compounds without having an exchange take place. 

T. Hanai, H. F. Walton, J. D. Navratil and D. Warren, Liquid chromatography of polar aromatic compounds on cation-exchange resins and porous polymer gels,/. Chromatogr., 1978, 155, 261-271. 

Park et al. [112] reported a series of porous carbons with well-developed pore structures, which were directly prepared from a weak acid cation exchange resin (CER) by the carbonization of a mixture with Mg acetate in different ratios (Fig. 2.21). By dissolving the MgO template, the porous carbons exhibited high specific surface areas (326-1,276 g ) and high pore volumes (0.258-... 

Porous silica-supported polymeric catalysts were prepared by sulfonation of divinylbenzene (DVB) or styrene-DVB copolymers with chlorosulfonic acid. The resultant acidic polymers had an ion-exchange capacity of up to 0.41 mequiv. g. ° Treatment of the styrene-divinylbenzene copolymer (one part) with chlorosulfonic acid (three to four parts) in 1,2-dichloroethane at 10-25 afforded the cation-exchange resin. ... 

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