Effects of Chitosan Concentration and Precipitation Bath Concentration on the Material Properties of Porous Crosslinked Chitosan Beads

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 C chitosan of chitosan in the chitosan/acetic acid solution and the concentration C NaOH of NaOH in the precipitation bath. We presented the way in which the values of C chitosan and CNoOH 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(ethylene 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(II). The results suggest that CRCS is a good matrix for introducing functional groups.