Studies of Polystyrene-based Ion-exchange Fiber. III. A Novel Fiber-form Chelating Exchanger and Its Adsorption Properties for Heavy-metal Ions

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Abstract
Fibrous chelating exchangers with –N(CH2COOH)2 and –N(CH2CH2COOH)2 groups have been prepared for the first time by using a polystyrene–polypropylene composite fiber as the starting material. They have large surface areas per unit of weight and can be utilized in various forms. The properties of adsorbing Cu2+ are compared between these chelating fibers and an ordinary chelating resin. The former groups form more stable complexes with Cu2+ than the latter, probably because of their different chelating structure. The rate of the adsorption of Cu2+ to the fibers is dependent upon their water content and is from ten to fifty times as high as that to the resin. These results are explained by assuming that the diffusion within the exchangers is the major rate-controlling step in the adsorption process. The diffusion equation of isotopic ion exchange for a cylindrical endless fiber was solved in the case of ideal particle-diffusion control by modifying the method used for a spherical resin. The experimental data are interpreted in terms of their theoretical solutions. For practical application, the removal of Cu2+ and Mn2+ from various solutions was also carried out by using fixed-beds of these chelating fibers.