Adsorbents polymeric

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. 

Recovery and Purification. The dalbaheptides are present in both the fermentation broth and the mycelial mass, from which they can be extracted with acetone or methanol, or by raising the pH of the harvested material, eg, to a pH of 10.5—11 for A47934 (16) (44) and A41030 (41) and actaplanin (Table 2) (28). A detailed review on the isolation of dalbaheptides has been written (14). Recovery from aqueous solution is made by ion pair (avoparcin) or butanol (teicoplanin) extraction. The described isolation schemes use ion-exchange matrices such as Dowex and Amberlite IR, acidic alumina, cross-linked polymeric adsorbents such as Diaion HP and Amberlite XAD, cation-exchange dextran gel (Sephadex), and polyamides in various sequences. Reverse-phase hplc, ion-exchange, or affinity resins may be used for further purification (14,89). 

Synthetic polymeric adsorbents have a high porosity, large surface area, and an inert hydrophobic surface. These resins can be regenerated ... 

A gas chromatographic determination of benzotrichloride and related compounds ia the work environment, after adsorption on a polymeric adsorbant and desorption with CCl has been reported (61). Trace amounts of benzyl chloride, benzal chloride, and benzotrichloride ia environmental samples can be analyzed by Method 8120 of EPA ManualSW-846 with modifications (62). 

Gaseous and particulate pollutants are withdrawn isoldnetically from an emission source and collected in a multicomponent sampling train. Principal components of the train include a high-efficiency glass- or quartz-fiber filter and a packed bed of porous polymeric adsorbent resin (typically XAD-2 or polyurethane foam for PCBs). The filter is used to collect organic-laden particulate materials and the porous polymeric resin to adsorb semivolatile organic species (com-... 

The value of n in the polymeric adsorbed species (CO) is larger on the 3c sites than on die 4c and 5c sites. The CO2 molecule is much more suongly adsorbed, indicating ion formation on the oxide surface, and the evidence suggests... 

In some cases it becomes necessary to use a chemical method of regeneration. Thus, phenolic substances, when adsorbed on activated carbons or polymeric adsorbents, are regenerated using aqueous solutions of sodium hydroxide of an appropriate concentration. 

Polymeric adsorbents have also been found to be very useful, and even highly water-loving undesired materials like p-toluene sulphonic acid from waste streams can be recovered via ad.sorption and regeneration with solvents like fv -propanol. In such instances, the regeneration of activated carbons is not satisfactory, even with aqueous sodium hydroxide. Solutes like phenols, substituted phenols, aromatic amines, heterocyclic amines (pyridine, picolines, etc.) can be recovered, in a rewarding way, from aqueous solutions. 

Vicenzi, J.T., Zmijewski, M.J., Reinhard, M.R. et al. (1997) Large-scale stereoselective enzymatic ketone reduction with in-situ product removal via polymeric adsorbent resins. Enzyme and Microbial Technology, 20, 494-499. 

We conclude that binary mixtures of solvent and displacer provide us with a valuable tool to obtain information on the interaction between a polymeric adsorbate and the substrate. Hopefully displacement studies will provide us with many new insights in the near future. 

Polymeric acyl titanate esters, 25 79 Polymeric adsorbents, properties and applications, l 587t... 

Interesting observations are made, if a polymeric adsorbate is capable of more than one mechanism of adsorption. If poly(styrene sulfonate) (PSS) is adsorbed on carbon black which contains multivalent cations on its surface, the adsorption depends strongly on the nature of the cations and on pH, with a maximum near pH 7. At very alkaline pH s, the OH ions compete with the sulfates for the cations and the PSS adsorption drops to the low values of hydrophobic bonding between the carbon itself and the PSS backbone. The latter low values are also obtained, if PSS is adsorbed on the same carbon after purification, i.e. when oxygen and/or the cations were removed. This adsorption of PSS is now pH independent (29). 

Kulprathipanja, S. (1988) Separahon of citric add from fermentahon broth with a neutral polymeric adsorbent. U.S. Patent 4,720,579. 

Kulprathipanja, S. and Oroskar, A.R. (1991) Separahon of an organic add from a fermentafron broth with an anionic polymeric adsorbent. U.S. Patent 5,068,419. 

Oulman, C. Trace organics removal using activated carbon and polymeric adsorbents. Municipal Environmental Research Laboratory, U.S. EPA Report 600/2-81-079, 1981. 

Kennedy, D.C. Treatment of effluent from manufacture of chlorinated pesticides with a synthetic, polymeric adsorbent, Amberlite XAD-4. Environ. Sci. Technol. 1973, 7 (2), 138-141. 

As mentioned, nnlike small analyte molecnles, macromolecnles can be irreversibly retained on the packing snrface in the given elnent and at given temperature (Section 16.6). In the case of interactions that lead to the adsorption of solnte on the adsorbent surface (Sections 16.3.5 and 16.6) this sitnation is described by the high-affinity isotherms (Figure 16.2) up to a certain threshold concentration of given polymeric adsorbate, all its molecules are adsorbed and their concentration in... 

Another form of head space analysis uses a purge trapping device to trap volatile impurities. In this technique a gas, e.g. helium, is bubbled through the sample which is dissolved in suitable solvent (usually water) and the volatile impurities are thus stripped from the solution and passed in the stream of gas through a polymeric adsorbant where they become trapped and thus concentrated. The stream of gas is then switched so it passes in reverse direction through the polymeric trap, which is heated to desorb the trapped volatiles and the gas stream is then diverted into the GC. This type of procedure is used in environmental analysis to concentrate volatiles in water which are present at low levels. 

Dowex Optipore is a polymeric adsorbent used to treat chlorinated volatile organic compound (CVOC) contaminated off-gas streams from remediation processes such as air stripping of groundwater and soil vapor extraction. According to the vendor Dowex Optipore adsorbent has the following advantages over activated carbon ... 

Rohm and Flaas Company has developed Amberlite polymeric adsorbent resins that can be used to remove organic compounds from contaminated groundwater, aqueous wastes, and vapor-phase wastes. Amberlite XAD-4 is a crosslinked polystyrene-type polymer. It is hydrophobic and has no ionic functional groups incorporated into its resin structure. The material is most useful in removing low-molecular-weight organic substances from aqueous systems. Amberlite XAD-4 has been commercially available since the 1970s. 

Table I. Characteristics of Polymeric Adsorbents Used for Water Analyses...

Rohm and Haas Co. Decolorization of Kraft Pulp Bleaching Effluents Using Amberlite XAD-8 Polymeric Adsorbent, IE-75 Philadelphia, 1972. 

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