Anion exchangers macroporous

Lewatit MP-500-FK (Mobay Chemical) Anion exchanger (macroporous, strong base) ci- 40 - 50 mesh - Wide... 

Fuactioaalizatioa is completed by aminating the chloromethylated copolymer with either primary or secoadary amines. Dimethyl amine [124 0-3] (6) is geaerally preferred, especially ia the syathesis of the macroporous anion exchangers. 

It is appropriate to refer here to the development of non-suppressed ion chromatography. A simple chromatographic system for anions which uses a conductivity detector but requires no suppressor column has been described by Fritz and co-workers.28 The anions are separated on a column of macroporous anion exchange resin which has a very low capacity, so that only a very dilute solution (ca 10 4M) of an aromatic organic acid salt (e.g. sodium phthalate) is required as the eluant. The low conductance of the eluant eliminates the need for a suppressor column and the separated anions can be detected by electrical conductance. In general, however, non-suppressed ion chromatography is an order of magnitude less sensitive than the suppressed mode. 

Highly active catalysts have been produced by adsorption of lipases onto macroporous acrylate beads, polypropylene particles and phenol-formaldehyde weak anion exchange resins. Protein is bound, presumably essentially as a monolayer, within the pores of the particles. The large surface area of the particles (10m2 g 1) means that substantial amounts of protein can be adsorbed, and the pores are of sufficient size to allow easy access of reactants to this adsorbed protein. 

Monolithic columns with the chiral anion exchange-type selectors incorporated into the polymer matrix obtained through in situ copolymerization process of a chiral monomer (in situ approach) [80-83,85] or attached to the surface of a reactive monolith in a subsequent derivatization step (postmodification strategy) [84], both turned out to be viable routes to enantioselective macroporous monolithic columns devoid of the limitations of packed columns mentioned earlier. 

Adsorption chromatography is an efficient way to isolate organic acids from large volumes of water. The nonionic, macroporous, Amberlite XAD-8 and the weak-base anion-exchange resin Duolite A-7 are two resins well suited for this purpose. These resins have been successfully used to extract organic acids from natural waters at sites where it was necessary to process thousands of gallons of sample. 

Large quantities of ion-exchange resin MSC-1, a strongly acidic macro-porous cation-exchange resin, or Duolite A-162, a strongly basic macroporous anion-exchange resin, were cleaned at one time. 

Fruit juices can be deacidified with a weak base anion-exchange resin. Removal of compounds which cause a bitter taste is a more popular application (26,27). It is accomplished with resins that have no ion-exchange fimctionality. In essence, they are similar to the copolymer intermediates used by resin manufacturers in the production of macroporous cation and anion exchangers. These products are called polymeric adsorbents. They are excellent for removal of limonin [1180-71-8] and naringin [1023647-2], the principal compounds responsible for bitterness in orange, lemon, and grapefruit juices. The adsorbents are regenerated with steam or alcohol. Decaffeination of coffee (qv) and tea (qv) is practiced with the same polymeric adsorbents (28). 

Carbonate cleanup was successful in restoring extraction efficiency to radiolyzed solutions when the diluent was CC14 (40) or tetrachloroethylene (41). With paraffinic hydrocarbons as diluents, a secondary clean-up operation was needed (181). Several efficient sorbents have been proposed, for example, macroporous anion-exchange resins, acid-washed activated charcoal, acid-washed alumina (20), or basic alumina (46). 

Naumczyk, I, Szpyrkowicz, L., and Grandi, F. Z. (1989). Organics isolation from fresh and drinking waters by macroporous anion-exchange resins. Water Res. 23,1593-1597. 

A cyclic polydimethylsiloxane was also prepared by the end-to-end reaction, i.e., a,ft)-dianion-functionalized polymers, which are then cyclized simply by reaction with a difunctional electrophile to give a cyclic polymer. The cyclic polydimethylsiloxane was synthesized from a commercially available o. tw-dihydroxy-polydimethylsiloxane (M = 2.460 g/mol). The Unear precursor was deprotonated using sodium hydride in dilute THF (< 10 2 M) and then end-coupled using a dichlorosilane coupUng agent (Fig. 53). The uncy-clized anionic linear precursors are then removed by a macroporous anion exchange resin. The successful cyclization and purification is monitored by IR and 29Si NMR, GPC, and MALDI-TOF mass [176],... 

Two commercial immobilized lipases were kindly supplied by Novozymes Brazil (Araucaria, PR, Brazil) Mucor miehei (Lipozyme IM) immobilized on a macroporous anion-exchange resin (0.15 U/g and 4 wt% water) and Candida antarctica (Novozym 435) immobilized on a macro-porous anionic resin (0.12 U/g and 1.4 wt% water). 

Chriswell and Cheng [65] have shown that chlorophenols and alkylphenols in the pbb to ppm range in non saline waters and treated drinking water can be determined by sorption on macroporous anion exchange resin, elution with acetone and measurement by gas chromatography. 

M. Kataoka, K. Tsuge and Y. Seto, Efficiency of pretreatment of aqueous samples using a macroporous strong anion-exchange resin on the determination of nerve gas hydrolysis products by gas chromatography-mass spectrometry after tert-butyldimethylsilylation, J. Chromatogr. A, 891, 295-304 (2000). 

Immobilization. We have worked with different carriers for immobilization. Active immobilized preparations have been obtained by adsorption on macroporous, weakly basic anion exchange resins, and on nonionic adsorbent resins. Resins of both acrylic and phenol-formaldehyde have been used (8). In the following examples we have used lipase immobilized on nonionic adsorbent acrylic resin. 

Enzyme preparation. The enzyme preparation Lipozyme IM, which is a Rhizomucor miehei lipase, immobilized on a macroporous anion exchange resin, was kindly donated from NOVO Nordisk AS (Copenhagen, Denmark). 

Macroporous anion-exchange resin, useful for the sorption of uranyl nitrate, has been prepared by suspension polymerization of 4-methyl-2-vinylpyridine with trimethylene glycol dimethacrylate... 

Zeng XE and Ruckenstein E. Cross-linked macroporous chitosan anion-exchange membranes for protein separations. J. Membr. Sci. 1998 148 195-205. 

It has been found [ 22, 23 ] that highly crosslinked macroporous cation exchangers are sufficiently resistant to oxidation for the treatment of wastewaters from both industries. The macroporous sulfonic acid resin, Amberhte 200, has a working life of 1 to 2 years, depending on the particular type of contacting equipment employed. Similarly, weak base macroporous anion exchangers can withstand such oxidizing environments for 1.5 to 2 years. 

Gel-type ion exchangers are much less resistant to osmotic shock than macroporous ones. For example, after the application of 70 cycles of osmotic shock (by treating sulfonic acid resins alternatively with 76% HNOg and wastewater from an ammonium nitrate processing plant), the number of cracked beads in the case of a gel-type resin (Wofatit KPS) was 78.3%, but for macroporous resins the number varied from only 1.2% (Amberlite 200) to 7.6% (Duolite C26) [24]. Similar results have been obtained for anion exchangers. Thus, the number of the... 

Fouling resistance (anion exchange resins) macroporous acrylic matrix... 

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