Metal ion imprinted microspheres

METAL ION-IMPRINTED MICROSPHERES PREPARED BY REORGANISATION OF COORDINATING GROUPS ON A SURFACE... 

Metal ion-imprinted microspheres were prepared as follows [14,15]. Seed emulsion was obtained by the polymerisation of styrene, butyl acrylate and methacrylic acid in water. Divinylbenzene, butyl acrylate and water were further added to the polymerisation mixture (seed emulsion) and the emulsion was left for a defined time so that the seed microspheres became swollen. The emulsion was combined with a metal ion solution to achieve complexation between the metal ion and the carboxyl group on the surface. Then the divinylbenzene-containing emulsion was polymerised by the use of y-rays at room temperature. The micro-spheres obtained by centrifugation were washed with a hydrochloric acid solution to remove the metal ion. The microspheres obtained were then dried under vacuum. Non-imprinted microspheres (as a reference) were synthesised similarly, but without a metal ion. 

PERCENTAGE ADSORPTION OF SINGLE METAL ION SPECIES ONTO NON-IMPRINTED AND METAL ION-IMPRINTED MICROSPHERES ... 

Fig. 9.1. Metal ion adsorption onto non-imprinted and metal ion-imprinted microspheres. Effect of the pH. Solid circles adsorption of Cu(II) onto Cu(II)-imprinted microsphere, open circles adsorption of Cu(II) onto non-imprinted microsphere, solid squares adsorption of Ni(II) onto Ni(II)-imprinted microsphere, open squares adsorption of Ni(II) onto non-imprinted microsphere. Conditions 0.05 g microspheres, 0.1 cm metal ion solution (5.0 x 10 mol/dm metal ion) and 12-18 h shaking time.

Yoshida, M. Uezu, K. Goto, M. Furusaki, S. Metal ion imprinted microspheres prepared by surface molecular imprinting technique using water-in-oU-in-water emulsion. J. Appl. Polym. Sci. 1999, 73, 1223-1230. 

The metal adsorption behaviour of the non-imprinted and Cu(II)-, Ni(ll)- and Co(II)-imprinted microspheres was examined at pH 5.6 [15]. The adsorption was expressed as the percentage of metal ions adsorbed on the resin with respect to the total amount of metal ions originally added to the solution (Table 9.1). 

Figure 9.1 shows the pH dependence of the metal-ion adsorption onto Cu(II)-and Ni(II)-imprinted microspheres and non-imprinted microspheres. Imprinted microspheres adsorbed the corresponding imprinted metal ions more effectively than did the non-imprinted microspheres over the entire pH range where metal ion adsorption took place. In all cases, the adsorption percentages increased with increasing pH. This means that the carboxyl groups on the microsphere surface participated in the metal-ion binding in their ionised carboxylate forms. 

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