REPRESENTATIVE ION-EXCHANGE RESINS

SE and SM are much stronger acids than CM, whereas P has two ionisable groups (pK 2-3, 6-7), one of which  

Sulfonated polystyrene Strong-acid cation exchanger 

AG 50W-X8 Amberlite IR-120 Dowex 50W-x8 Duolite 225 Permutit RS Permutite C50D 

Aliphatic amine-type weak base anion exchangers 

Amberlite lRA-400 Dowex 2-x8 Duolite 113 Permutit ESB Permutite 330D 

AG 50W-x8 Amberlite IR-120 Dowex 50W-x8 Duolite 225 Permutit RS Permutite C50D (Bio-Rad, USA) (Rohm and Haas, USA) (Dow Chemical Co., USA) (Dia-Prosim Ltd) (Permutit AG, Germany) (Phillips and Pain-Vermorel, France) 

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TABLE 12. REPRESENTATIVE ION-EXCHANGE RESINS USED IN CHROMATOGRAPHY ... 

The distance d corresponds to the movement of solute and mobile phase from the starting (sample spotting) line. Subscript r represents an ion-exchange resin phase. Two immiscible liquid phases might be represented similarly using subscripts 1 and 2. ... 

The ratio of reactants had to be controlled very closely to suppress these impurities. Recovery of the acrylamide product from the acid process was the most expensive and difficult part of the process. Large scale production depended on two different methods. If soHd crystalline monomer was desired, the acrylamide sulfate was neutralized with ammonia to yield ammonium sulfate. The acrylamide crystallized on cooling, leaving ammonium sulfate, which had to be disposed of in some way. The second method of purification involved ion exclusion (68), which utilized a sulfonic acid ion-exchange resin and produced a dilute solution of acrylamide in water. A dilute sulfuric acid waste stream was again produced, and, in either case, the waste stream represented a... 

The selectivity of an ion-exchange resin means its ability to discriminate among different ionic species. A cation-exchange reaction can be represented by an equation of the form... 

Although many radiation-grafted materials have been discovered, only a limited number of them have been commercially utilized. One of the first successful applications was the use of grafted films in battery separators. Other possibilities are in ion exchange resins and membranes for separation processes. The textile industry represents opportunities in improving... 

Table 29-1 contains information about a number of representative important polymers and their uses. Some similar data on other polymers already have been given (Section 13-4 and Table 10-4). The important use of modified polymers as ion-exchange resins is discussed in Section 25-4C.

Figure 16 Comparison of the dimensionless force Y and fractional deformation of a single 163 pm diameter ion-exchange resin particle (DOWEX 1X8-200, Sigma-Aldrich, UK) obtained by diametrical compression and by numerical simulation using the Tatara non-linear elastic model. E0n represents the initial Young s modulus at zero strain (data provided by Dr T. Liu).

A more complex field of ion-exchange application is associated with the separation of mixtures of substances that react similarly with ion-exchange resins. In this case the separation is based on differences in resin selectivity toward the mixture s components. These differences are characterized by the magnitude of the equilibrium separation coefficient which can be represented for a pair of ions as follows ... 

Fig. 5. Diffusion spectra for water traveling through close-packed ion-exchange resin beads (50-100 mesh) at flow rates of 13 ml hr" (solid circles), 25 ml hr" (open squares), 50 ml hr" (open circles), and 100 ml hr" (solid squares). The crosses represent the measured spectrum for stationary water. The lines are to guide the eye. The pronounced peak is believed to arise from the oscillatory motion of water around the beads, while the low-frequency plateau is due to perfusive spreading of the flow. [Reproduced by permission from Callaghan and Stepisnik, 1995a.]...

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