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The equilibrium isotherm and the breakthrough curve for adsorption of Hg(II) on polyaminated highly porous chitosan beads (PEI-CS) were compared with those for Unicellex UR-120H which was the best commercial chelate resin for removal of Hg(II) in Japan. As the intraparticle effective diffusivity Deff in PEI-CS was about two times larger than that in UR 120H, and adsorption capacity Hg(II) on PEI-CS was also larger than that on UR-120H, adsorption of Hg(II) on PEI-CS appeared feasible technically. The intraparticle concentration profiles of Hg(II) were measured for different period of time using X-ray micro-analyzer. The value of Deff was almost constant at 4 Re′ 7, and the mean value was 3.86 × 10−12 m2/s. The value od Deff increased in proportion to the influent concentration of Hg(II) Co,Hg. The pore diffusivity and surface diffusivity were determined using Deff based on the parallel transport model of surface and pore diffusions. The result showed that both the pore and surface diffusions of Hg(II) in PEI-CS particle were significant.

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Flaked chitosan obtained by deacetylating 80% of chitin extracted from crab shell was dissolved in acetic acid aqueous solution, and highly porous chitosan beads were formed by dropping the chitosan solution into aqueous NaOH solution, followed by crosslinking with ethylene glycol diglycidyl ether. Fifteen different crosslinked chitosan beads (CRCS) were fabricated by controlling the concentration Cchiroran of chitosan in the chitosadacetic acid solution and the concentration C N~O H of NaOH in the precipitation bath. We presented the way in which the values of Cch,,osan and CNaOH were controlled to fabricate chitosan beads with any desired values of the apparent density, the solid phase concentration of amino group, the pore radius, the total porosity, and the specific surface area. In order to assess the possibility of using CRCS as a matrix of an adsorbent for the separation of metal ions, poly(ethy1ene imine) was introduced onto the CRCS which had a relatively high concentration of amino group. The polyaminated CRCS had a high capacity, and it had a high selectivity for the adsorption of Hg(II), Cu(II), Ni(II), Cd(II), and Zn(I1). The results suggest that CRCS is a good matrix for introducing functional groups. 1959Copyright 0 1997 by Marcel Dekker, Inc. 1960KAWAMURA ET AL.

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