Adsorption by ion exchange

Deasbing The removal from solution of inorganic salts by means of adsorption by ion-exchange resins of both the cations and the anions that comprise the salts. See deionization. 

In the first step the solution enters the pores. The driving forces for the flow are capillary forces. During the flow, adsorption by ion exchange occurs. Due to the high rate of adsorption an uneven distribution of Pt ions results. Subsequently, a situation exists in which the diffusion through the pore mouth becomes rate determining. The active phase is pre.sent as a shell, which moves towards the interior of the particle as shown in Fig. 3.30. 

Adsorption by ion exchange Exchange adsorption can take place through exchange of either lattice ions or counterions. An example of exchange of lattice ions is... 

In addition to the electrostatic consequences of specific charge-charge interactions, surfactant adsorption by ion exchange or ion pairing results in the orientation of the molecules with their hydrophobic groups toward the aqueous phase therefore, the surface becomes hydrophobic and less easily wetted by that phase. Once the solid surface has become hydrophobic, it is possible for adsorption to continue by dispersion force interactions (Fig. 9.15). 

The adsorption by ion exchange resins of metallic ions removed by dissolution of magnetite layer of the coupon specimens in the decontamination formulations was studied in the glass loop experiments. Inactive metal ions of iron, nickel and activated corrosion products Co-60, Co-58, Mn-54 and fission products Cs-137, Ce-141, Ce-144, Pr-144 were also effectively removed by the cation exchange resins. Ru-103, Sb-125 were taken up by anion exchange resins. Ru-106, Zr-95 and Nb-95 were taken up by bodi the ion exchange resins. 

Pharmaceutical. Ion-exchange resins are useful in both the production of pharmaceuticals (qv) and the oral adrninistration of medicine (32). Antibiotics (qv), such as streptomycin [57-92-17, neomycin [1404-04-2] (33), and cephalosporin C [61-24-5] (34), which are produced by fermentation, are recovered, concentrated, and purified by adsorption on ion-exchange resins, or polymeric adsorbents. Impurities are removed from other types of pharmaceutical products in a similar manner. Resins serve as catalysts in the manufacture of intermediate chemicals. 

Table 16-1 classifies sorption operations by the type of interaction and the basis for the separation. In addition to the normal sorption operations of adsorption and ion exchange, some other similar separations are included. Applications are discussed in this section in Process Cycles. ... 

Separation Factor By analogy with the mass-action case and appropriate for both adsorption and ion exchange, a separation factor / can be defined based on dimensionless system variables [Eq. (16-10)] by... 

New templated polymer support materials have been developed for use as re versed-phase packing materials. Pore size and particle size have not usually been precisely controlled by conventional suspension polymerization. A templated polymerization is used to obtain controllable pore size and particle-size distribution. In this technique, hydrophilic monomers and divinylbenzene are formulated and filled into pores in templated silica material, at room temperature. After polymerization, the templated silica material is removed by base hydrolysis. The surface of the polymer may be modified in various ways to obtain the desired functionality. The particles are useful in chromatography, adsorption, and ion exchange and as polymeric supports of catalysts (39,40). 

From culture of Streptomyces verticillus by ion-exchange adsorption and column chromatographic purification (on alumina) via the copper complex. 

From culture of Streptomyces capreolus by ion-exchange adsorption. Reference(s) ... 

Adsorption (including both physical adsorption and ion exchange) by clay minerals and silicates... 

---