To obtain a novel acid-base catalyst of high activity and easy treatment, we have prepared polystyrene-based fibrous ion exchange catalysts which have large surface areas per unit of weight and which can be utilized in various forms. They are excellent in chemical stability and mechanical strength due to their composite structures, reinforced with polypropyrene. The reactions of sucrose inversion and methyl acetate hydrolysis were carried out by using these cation exchange fibers and ordinary cation exchange resins. The fiber has about sixteen times as high a catalytic activity per equivalent acid as the resin in the case of sucrose inversion. The intrinsic rate constant in the fiber phase is evaluated to be 2.4 times larger than that in the resin phase in terms of the solid-catalysis theory considering the catalytic effectiveness factor and the absorption coefficient. On the other hand, the catalytic activity per equivalent acid of the fiber is almost equal to that of the resin in the case of methyl acetate hydrolysis. It is suggested that this different behavior is attributable to the different molecular sizes of the reactants.
A polystyrene-based ion exchange fiber which has a large ion exchange capacity (ca. 2.5 mequiv g−1) and a high mechanical strength (ca. 1.4 g d−1) has first been prepared by using an islands-in-a-sea type composite fiber, the sea ingredient predominantly comprised of polystyrene for ion exchange and the island ingredient comprised of fiber-forming polypropylene for reinforcement, as the starting material; it can be used in an arbitrary form. It was found that the resulting fiber has two fundamental characteristics; the ion exchange rate for metal ions is extremely high, and the capacity of adsorbing the macromolecular ionic substance is exceedingly large, compared with ordinary ion exchange resins. The diffusion equation of ion exchange in the case of a cylindrical, endless fiber was solved by a modification of the method used for a spherical resin in a simple system. The former results are interpreted in terms of their solutions for two limiting cases. The latter results are explained by the fact that the surface-area ratio of the fiber to the resin is about ten.
Immobilization of microorganism cells by adsorption on a new polystyrene-based ion-exchange fiber has been studied. Microorganism cells, such as yeasts, bacteria, and actinomycetes, were well adsorbed on the anion-exchange fibers through an electrostatic force. The adsorption capacity for the cells became much greater as the water-holding capacity of the fibers increased. The adsorption and desorption behavior of the cells was different between actinomycetes and yeasts, and also between strong and weak anionexchange fibers. The enzyme activities of the immobilized actinomycetes containing glucose isomerase and yeasts containing l-aminolactam hydrolase were ca. 70 and 60% of those of the native cells respectively. The stability of the immobilized yeasts in the hydrolysis of Dl-cyclic lysine anhydride was also investigated.
A new polystyrene-based ion-exchange fiber (IONEX) has a large surface area per unit weight and has been studied for its ability to adsorb and immobilize biologically-active proteins. A strong cation IONEX was found to be able to effectively adsorb hemoglobin and albumin, invertase, and glucose isomerase were readily adsorbed to a strong anion IONEX. The adsorption of these proteins to IONEX was found to take place through an electrostatic force. The adsorption capacity for proteins became exceedingly large (ca. 300 mg g−1) with an increase in the water-holding capacity of the fiber. The activities of the invertase and glucose isomerase immobilized to the fiber exhibited 40–50 and 75–80%, respectively, of those of native enzymes. A continuous inversion of sucrose was also carried out using immobilized invertase. From these results, this fibrous ion exchanger with a high water-holding capacity is considered to be an excellent material for the adsorption and immobilization of proteins.
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