Adsorption of lead(II) ion on complexane types of chemically modified chitosan

Two kinds of complexane-type of chitosan chemically modified with EDTA and DTPA were synthesized and examined concerning the adsorption behavior for iron(III), copper(II), nickel(II), zinc(II), aluminium(III), and lead(II) from a dilute hydrochloric acid solution. Both of these adsorbents were found to adsorb lead(II) at low pH in a similar highly selective manner over zinc regardless of the kind of acid, whether it be hydrochloric acid or nitric acid, and to have a much stronger adsorption power compared with a commercial phosphonamidic acid-type chelating resin. The maximum adsorption capacities of lead were 1.8 and 1.5 mol/kg-dry gel for DTPA-and EDTA-chitosan. The breakthrough followed by elution tests demonstrated that it is achievable to concentrate a small amount of lead(II) which has been very selectively separated from a large excess of zinc by using an adsorption column packed with these adsorbents.