High Ion-exchange

Phosphonomethylated Ethers. A phosphoms-containing ether of ceUulose can be prepared by the reaction of cotton ceUulose with chioromethylphosphonic acid [2565-58-4] ia the presence of sodium hydroxide [1310-73-2] by the pad-dry-cure technique (62). Phosphoms contents of between 0.2 and 4.0% are obtained. This finish is durable but has high ion-exchange properties and is flame resistant only as the ammonium salt. DurabUity on medium weight fabrics is obtained with chi oromethylph osph onic diamide. This finish has never penetrated the flame retardant market (63). 

Extremely high ion exchange affinities are however sometimes observed for alkali metals (e.g. Cs) and transition metal ion complexes in clay minerals and zeolites. The objective of this paper is to give an account of the factors which are involved in these high selectivity phenomena. The discussion will be focussed mostly on montmorillonites and faujasites as representatives of the phyllosilicate and tectosilicate groups. 

Elabd, Y. A. and Napadensky E. 2004. Sulfonation and characterization of poly(styrene-isobutylene-styrene) triblock copolymers at high ion-exchange capacities. Polymer 45 3037-3043. 

Studies by Pintauro and co-workers have shown that poly [(3-methylphenoxy) (phenoxy) phosphazene] and poly [bis (3-methylphenoxy) phosphazene] (Figure 37) can be sulfonated by adding an SO3 solution in dichloroethane dropwise to a polymer/dichloroethane solution.A high ion exchange capacity (up to 2.0 mequiv/g) material was reported with no detectable polymer degradation. 

In the case of amorphous intermediate 4, the weakly acidic cation exchange resin DIAION WKIOO was selected as the CEC stationary phase. The resin comprises a methacrylate resin matrix and carboxylic acid, which functions as an exchange group with a high ion exchange rate. Figure 9.4 illustrates the concept behind the CEC procedure for 4 ... 

In a first step styrene is partially polymerized and cross-linked with divinylbenzene and then in a second step sulfonated with concentrated sulfuric acid. The obtained membranes show high ion-exchange capacity and low electrical resistance. To increase the mechanical strength the membrane is cast on a support screen. 

The cations on the as-made pillared clays are protons. The ion-exchange capacity of the original clay is preserved in the hnal pillared clay. Hence, PILCs can have very large ion-exchange capacities, for example, 140 meq/g for the Arizona montmorillonite. The high ion-exchange capacities of PILCs are potentially useful for ion exchange applications. 

These materials are widely applied for hardness removal, and demineralization and purification of water, since they have high ion-exchange capacities even at low concentrations of the ion to be removed in solution, and are stable and easily regenerated. 

ETS-10 is a titanosilicate with a three-dimensional 12-ring pore system and a very high ion-exchange capacity. The integral heats of adsorption of monoalkyl-amines on ETS-10 have been measured by isothermal calorimetry as a funchon of the n-alkylamine concentrahon [118]. The heats vary in the order methyl < ethyl < propyl < butyl amine. 

Synthetic Insoluble Silicates. Insoluble crystalline siUcates, ie, mineral-type compounds, are synthesized from soluble siUcates by precipitation, gelation, ion exchange, and hydrothermal techniques. Hydrothermal treatment of partially neutralized, high mole ratio (m = 12—50), sodium siUcate solutions yields neutral alkaU polysiUcates that exhibit a layered stmcture and high ion-exchange capacity (135,136). These and other lamellar siUcates can be utilized either alone or modified via pillaring (137) as adsorbents and catalysts. 

In this presentation we, therefore, investigate the kinetics of ion exchange in such mixtures for the case vdiere diffusion of the ions across a hydrostatic boundary layer (Nemst film) surrounding the particles is the rate controlling step (film diffusion). In well-stirred systems, liquid-phase mass transfer will usually be fevored by a low concentration of the external solution, a high ion-exchange capacity, and a small particle size [I]-... 

Based on these experiments, to separate Pd(II) effectively by an ion exchange method from radioactive liquid waste, the development of anion exchanger with the high ion exchange capacity for Pd(II) may be important... 

Chemical fractionation behavior in which the elements are highly ion-exchangeable or partly ion-exchangeable and partly acid soluble. 

Membranes with a high ion exchange capacity are desirable for the production of concentrated caustic soda, and it is therefore essential to use PVEX monomer with m = 0 as a comonomer. 

As a result, the perfluorocarboxylated membrane with a high ion exchange capacity attains a high fixed ion concentration, which is defined as milliequivalent of carboxylic acid group per a gram of absorbed water in the membrane. 

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