Resins selectivity

DeioniZa.tlon, The removal of cations and anions from water and replacement of them with hydrogen and hydroxide ions is called deionization. The completeness of the ionic removal is dependent on resin selection, design of the system, operating conditions, and the quaUty of treated water required. In general, systems become more complex as quaUty requirements increase. 

Adhesives. Contact adhesives are blends of mbber, phenoHc resin, and additives suppHed in solvent or aqueous dispersion form they are typically appHed to both surfaces to be joined (80). Evaporation of the solvent leaves an adhesive film that forms a strong, peel-resistant bond. Contact adhesives are used widely in the furniture and constmction industries and also in the automotive and footwear industries. The phenoHc resins promote adhesion and act as tackifiers, usually at a concentration of 20—40%. In solvent-based contact adhesives, neoprene is preferred, whereas nitrile is used in specialty appHcations. The type and grade of phenoHc resin selected control tack time, bond strength, and durabiHty. 

Table 3. Chelating Cation Resin Selectivities for Metal Ions.

The crosslinking reactions are illustrated in Reaction 1.8, and they demonstrate that, in principle, only a trace of curing agent is necessary to bring about cure of epoxy resins. Selection of curing agent depends on various considerations, such as cost, ease of handling, pot life, cure rates, and the mechanical, electrical, or thermal properties required in the final resin. 

Utilizing electrolytic recovery, customized resins, selective membranes, and adsorbents to separate metal impurities from plating baths, acid/caustic dips, and solvent cleaning operations. 

Primary metals manufacturing operations have experienced source reduction and recycle/reuse benefits similar to those available to metal finishing operations, including conserving waters through countercurrent rinsing techniques, and utilizing electrolytic recovery, customized resins, selective membranes, and adsorbents to separate metal impurities from acid/caustic dips and rinsewaters to thereby allow for recycle and reuse. 

USP acid test analy chem A United States Pharmacopoeia test to determine the carbonizable substances present In petroleum white oils. yti es pe as ad. test) UV stabilizer chem Any chemical compound that, admixed with a thermoplastic resin, selectively absorbs ultraviolet rays used to prevent ultraviolet degradation of polymers. Also known as ultraviolet stabilizer. yu ve sta ba.iTz ar)... 

AS = 13 e.u. for the Cu-template resin, and AH = -0.8, AS = 9,8 (K - 540) for the resin synthesized without any template ion. The larger change in entropy observed in the complexation of the Cu-template resin indicated that die Cu-template resin selectively adsorbed Cu ions by entropic effect. Furthermore, the absorption spectrum of the Cu complex of the Cu template resin was located at a wavelength 10—20 nm shorter than those of the other resins70 and the ESR parameters of the Cu complex of the Cu-template resin were similar to those of the non-distorted planar Cu complex71. From these results, it was suggested that the conformation of the polymer-ligand chain in the Cu template resin remained the best one for the Cu ion. 

The cost of the Duolite GT-73 is much higher than the other resins selected in the Navy study. The volume of waste generated at our facility is a thousand times less than the volume generated in the Navy study and the local discharge limit is not as low. Therefore one of the other three resins may be more cost-effective. 

The following sections will focus on the properties of ion-exchange resins, selection of experimental conditions, and applications of ion-exchange chromatography. 

FIGURE 9.14 Comparison of reductants for on-column conversion of Pu(IV) to Pu(III) in order to release the Pu from the TRU-Resin selectively. (Adapted from Grate, J. W. and Egorov, O., Anal. Chem., 70, 3920-3929, 1998. Copyright 1998 Am. Chem. Soc. With permission.)... 

Figure 2. Correlation of water contact angles for different counterions with anion-exchange resin selectivity data of Gregor et al. (13)...

Assuming the selectivity of the resin for sodium is 1, the relative selectivity for magnesium, calcium, and strontium would be 1.7, 2.6, and 3.3, respectively. Selectivity is related to valence or charge on the ion.The higher the valence, the higher the SAC resin selectivity for that ion. 

Chemical attack Poor resin selection or change in environmental conditions... 

Tanks and process Chemical attack Poor resin selection, or environmental... 

UV stabilizer Any chemical compound which, when mixed with a thermoplastic resin, selectively absorbs UV rays. 

Ultrasonic nebulizers have also been employed in continuous flow systems as interfaces between sample preparation steps in the analytical process and detection by virtue of their suitability for operating in a continuous mode. Thus, preconcentration devices have commonly been coupled to atomic spectrometers in order to increase the sensitivity of some analytical methods. An enhancement factor of 100 (10 due to USNn and 10 due to preconcentration) was obtained in the determination of platinum in water using a column packed with polyurethane foam loaded with thiocyanate to form a platinum-thiocyanate complex [51]. An enhancement factor of 216 (12 with USNn and 18 with preconcentration) was obtained in the determination of low cadmium concentrations in wine by sorption of metallic complexes with pyridylazo reagents on the inner walls of a PTFE knotted reactor [52]. One special example is the sequential determination of As(lll) and As(V) in water by coupling a preconcentration system to an ICP-AES instrument equipped with a USN. For this purpose, two columns packed with two different resins selective for each arsenic species were connected via a 16-port valve in order to concentrate them for their subsequent sequential elution to the spectrometer [53]. 

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 ... 

The previous considerations now provide a basis for describing the principal chemical and physical characteristics of many commonly used ion exchange resins, as defined in the product technical data sheets available from all major resin manufacturers. Some selected values typical of such data are given in Tables 4.2 and 4.3 which along with the following discussion establishes a basis for optimum resin selection. 

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