We have been able to prove that not only adsorption but also complexation of
different metals (Pb, Cd, Mo, Cu, Zn and Cr) actually takes place in acetate
buffer (pH=4) with Chitosans of different molecular weights and deacetylation
degrees. Depending on the different electrochemical behaviour on mercury electrode
of studied metals and the nature of the resulting complexes, diverse approaches
have been used.
Chitosan molecular weight and concentration had been seen to play a key role
in the Chitosan binding activity with Zn, Pb and Cd, as reported elsewhere[1].
Length of Chitosan chains influences the degree of complexation with both Cr
and Mo, while Cu binding capacity remains independent of the molecular weight
of the assayed polymers. The larger the polymer chain length the higher the
number of amino group available for the retention of both Cr and Mo within
the tridimensional structure of the acting ligand. This is consistent with a
predominant intra-chain linkage of both metal atoms. On the contrary, in the
case of Cu, an inter-layer binding mechanism is proposed as the main retention
factor by Chitosan
