Resin of ion-exchange

PEI derivatives have proven to be effective carriers of cations in Hquid membrane systems (404). This technology led to the development of ion-exchange resins (405), which are also suitable for extracting uranium from seawater (406). 

Manufacture of ion-exchange resins has traditionaHy been a batch process. Significant progress was made more recentiy in the development of a continuous process for the manufacture of copolymer beads. However, as of this writing (ca 1994) is it not used by aH manufacturers. Moreover, those companies having continuous processing capabiHties do not use it for aH ion-exchange products. 

Radiation Stability. Numerous studies have been undertaken to define the effect of radiation on all types of ion-exchange resins. As... 

Historically the United States was a primary exporter of ion-exchange resin. As of 1994, the United States imports substantially more than it exports. Because compliance with tightening environmental regulations in the United States impacts on the cost of manufacture, offshore resin is most often lower in price. 

Divinylbenzene copolymers with styrene are produced extensively as supports for the active sites of ion-exchange resins and in biochemical synthesis. About 1—10 wt % divinylbenzene is used, depending on the required rigidity of the cross-linked gel, and the polymerization is carried out as a suspension of the monomer-phase droplets in water, usually as a batch process. Several studies have been reported on the reaction kinetics (200,201). 

J. Korkisch, Handbook of Ion Exchange Resins Their Applications to Inorganic Analytical Chemistry, 6 Vol. Set, CRC Press, Boca Raton, 1989. ISBN 0849331943. 

The amino acid and the ammonium chloride may conveniently be separated by passing through a column of ion-exchange resins. The amino acid melts at 195°C. 

Variances in resin performance and capacities can be expected from normal annual attrition rates of ion-exchange resins. Typical attrition losses that can be expected include (1) Strong cation resin 3 percent per year for three years or 1,000,000 gals/ cu.ft (2) Strong anion resin 25 percent per year for two years or 1,000,000 gals/ cu.ft (3) Weak cation/anion 10 percent per year for two years or 750,000 gals/ cu. ft. A steady falloff of resin-exchange capacity is a matter of concern to the operator and is due to several conditions ... 

Table 2. Selectivity of ion Exchange Resins in Order of Decreasing Preference.

Batch operation The utilization of ion-exchange resins to treat a solution in a container wherein the removal of ions is accomplished by agitation of the solution and subsequent decanting of the treated liquid. 

Bed A mass of ion-exchange resin particles contained in a column. Bed depth The height of the resinous material in the column after the exchanger has been properly conditioned for effective operation. Bed expansion The effect produced during backwashing when the resin particles become separated and rise in the column. The... 

Column operation Conventional utilization of ion-exchange resins in columns through which pass, either upflow or downflow, the solution to be treated. 

Static system The batch-wise employment of ion-exchange resins, wherein (since ion exchange is an equilibrium reaction) a definite endpoint is reached in which a finite quantity of all the ions involved is present. Opposed to a dynamic, column-type operation. 

Sybron Chemicals Inc.,A Look at the Synthesis of Ion-Exchange Resins, McGraw-Hill Publishing Co. Inc., New York, 1963. 

Filtered broth was passed at 2.5 ml/min through a resin column (2.5 cm diameter, 28 cm length) packed with 150 ml of ion exchange resin Amberlite IRC-50 sodium type (Rohm and Haas Co., U.S.A.). The column was washed with water, eluted with 0.5 N HCI at a flow rate 1.3 ml/min. The eluates were fractionated each 10 ml and tuberactinomycin-N activity was found at fractions No. 45-63 obsarved by ultraviolet absorption method and bioassay. 

In recent years, the rate of information available on the use of ion-exchange resins as reaction catalysts has increased, and the practical application of ion-exchanger catalysis in the field of chemistry has been widely developed. Ion-exchangers are already used in more than twenty types of different chemical reactions. Some of the significant examples of the applications of ion-exchange catalysis are in hydration [1,2], dehydration [3,4], esterification [5,6], alkylation [7], condensation [8-11], and polymerization, and isomerization reactions [12-14]. Cationic resins in form, also used as catalysts in the hydrolysis reactions, and the literature on hydrolysis itself is quite extensive [15-28], Several types of ion exchange catalysts have been used in the hydrolysis of different compounds. Some of these are given in Table 1. 

There are several apparent advantages to the use of ion-exchange resins as either acid or base catalysts, several of which are as follows ... 

There are many applications of ion-exchange resins in analytical chemistry in both quantitative and qualitative... 

New types of ion exchange resins have also been developed to meet the specific needs of high-performance liquid chromatography (HPLC) (Chapter 8). These include pellicular resins and microparticle packings (e.g. the Aminex-type resins produced by Bio-Rad). A review of the care, use and application of the various ion exchange packings available for HPLC is given in Ref. 19. 

Some of the commercially available ion exchange resins are collected in Table 7.1. These resins, produced by different manufacturers, are often interchangeable and similar types will generally behave in a similar manner. For a more comprehensive list of ion exchange resins and their properties, reference may be made to the booklet published by BDH Ltd (see the Bibliography, Section 9.10). 

Nature of ion exchange resin. The absorption of ions will depend upon the nature of the functional groups in the resin. It will also depend upon the degree of cross-linking as the degree of cross-linking is increased, resins become more selective towards ions of different sizes (the volume of the ion is assumed to include the water of hydration) the ion with the smaller hydrated volume will usually be absorbed preferentially. 

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