Resins types exchange

PhenoHc-based resins have almost disappeared. A few other resin types are available commercially but have not made a significant impact. Inorganic materials retain importance in a number of areas where synthetic organic ion-exchange resins are not normally used. Only the latter are discussed here. This article places emphasis on the styrenic and acryHc resins that are made as small beads. Other forms of synthetic ion-exchange materials such as membranes, papers, fibers (qv), foams (qv), and Hquid extractants are not included (see Extraction, liquid-liquid Membrane technology Paper.). 

Weak and strong acid-type resins are for removal of cations and are called cation exchangers. Weak and strong base resins remove anions and are called anion exchangers. In addition to these four resin types, there are specialty resins used in appHcations where higher specificity for certain ions under challenging conditions is a critical factor. 

Eig. 5. Pressure drop as affected by resin type, flow rate, and temperature, where A, B, and C, correspond respectively to acryUc strong base anion exchanger (Amberlite IRA-458), styrenic strong base anion exchanger (Amberlite IRA-402), and styrenic strong acid cation exchanger (Amberlite IR-120), all at 4°C. D represents styrenic strong acid cation resin (Amberlite IR-120) at 50°C (14). To convert kg/(cm -m) to lb/(in. -ft), multiply by 4.33 to convert... 

Nevertheless, despite all the new resins primarily designed for specialist market niches, for the most part we are primarily concerned with a limited number of standard resin types that provide common exchange functions for general industrial and institutional boiler plant processes such as ... 

Resin type Functional group Mobile ion PH range for exchange Resin (regeneration, preparation) wash with Trade names of market products... 

Somewhat smaller < -factors and larger hfs intervals were exhibited by charcoal, zeolite, and a carboxylic acid-type exchange resin, indicating more covalent character in the metal-adsorbent bond. 

For gel-type exchange resins and for macropore resins with a low degree of cross-linking, the following equation is proposed for the solid diffusion coefficient (Helfferich, 1962) ... 

Resin type Bulk wet density A, (kg/m3) Maximum operating temperature Exchange capacity (dry resin) Qmax (meq/g)... 

The principle of ion exchange is based on the fact that some solid materials exchange ions when in contact with a solution. The most commonly used materials are the resin ion exchangers. These have replaced most of the older aluminosilicate or hydrated oxide materials, and are available in a number of types and particle sizes. 

The data presented lead to the general conclusion that Dowex anion-exchange resins (types 1x8 50-400, 1x4 50-400, and 1x2 100-400 styrene-... 

The most frequently used resin type for water softening is the Na type. A typical ion-exchange reaction is described by Eq. (29). Owing to the presence of NaHCOg, treated effluent pH is always weakly caustic. The regeneration of resin performed with sodium chloride solution is described by Eq. (30) ... 

In the ion exchange process, ions with higher affinity to the resin can replace those with lower affinity. A strong basic anion exchange resin (type 201 x 7) is used. There are several anions like WO , MoO , HAsO , HPO , SiOf", OH , etc. in the sodium tungstate solution. Beside OH , all others have higher affinity than Cl and can be adsorbed by the resin as follows ... 

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