(46e) Equilibria for Adsorption of Heavy Metal Ions on Chitosan Fiber and Highly Porous Chitosan Bead

In this study, cross-linked chitosan fibers were used as an adsorbent, and the adsorption equilibrium characteristics (adsorption isotherm and pH dependence of amount adsorbed (q-pH curve)) of valuable metal ions (Cu(II), Ni(II), Co(II), Cd(II), Mn(II) and Li(I)) were investigated for the purpose of adsorptive separation of metal ions only in the pH operation. From the result of pH adsorption isotherm in single component systems, it was proven that the amount adsorbed of metal ions on cross-linked chitosan fiber is strongly dependent on pH of the aqueous solution. Since the behavior is different by each metal ion, the adsorptive separation of each metal ion was possible using the difference among the amount adsorbed of each metal ion by pH change of the aqueous solution. In addition, the amount adsorbed of each metal ion on cross-linked chitosan fiber was well able to correlate by Langmuir adsorption isotherm. It increased with an increase in pH of the aqueous solution and indicated the maximum value near neutrality. On the other hand, the adsorption equilibrium relation of two-component metal ions systems could not correlate in Marhkham-Benton equation, which was expanded Langmuir equation for the two-component systems. However, one metal ion may be selectively adsorbed on cross-linked chitosan fiber by well chosen two-component systems, and the better adsorptive separation of each component from mixtures will be achieved, because the amount adsorbed for the other metal ion drastically decreases and the difference of the amount adsorbed of the binary ions increases very much.