Ethylenediamine tetraacetic acid modification of crosslinked chitosan designed for a novel metal-ion adsorbent

Novel chitosan-based adsorbent materials were synthesized with a higher fatty diacid diglycidyl as a crosslinking agent, and the adsorption ability of the resulting polymers for several metal ions was evaluated. Selective adsorption for Cu2+ in comparison with other divalent metal ions, such as Ni2+, Pb2+, Cd2+, and Ca2+, was observed with the crosslinked chitosan sorbent at pH 6; however, the adsorption power decreased abruptly as the pH value of the solution decreased. The addition of ethylenediamine tetraacetic acid (EDTA) residues to crosslinked chitosan significantly enhanced the adsorption power for metal ions, especially for Ca2+. The adsorptivity of Ca2+ was dramatically improved with the introduction of EDTA residues, and the value was greater than that obtained with a commercial chelate resin (CR11). Although the adsorption power of the EDTA-derivatized sorbent for other metal ions was just comparable to that of the CR11 material, the newly synthesized adsorbent could be used for the recovery of metal ions from industrial waste solutions with a relatively wide range of pHs, from 4.0 to 6.0. (C) 2004 Wiley Periodicals, Inc.