From: Jack Sullivan (jsulliva$##$eclipse.net)
Date: Mon Mar 06 2000 - 09:15:10 EST
lia kamelia wrote:
>
> dear people
>
> i read that chitosan is the chelating agents for metal ions, can u
> tell me what metal ions is it? and why?
>
> thanks
>
Chitosan is "a first-rank chelating polymer of transition metals (1).
... Chitosan collects metal ions selectively, that is, it does not take
up alkali or alkali-earth ions but it collects transition and
post-transition metal ions. The metal collection rate depends on pH of
the solution, counter ions of metal salts, etc." (Chitin, Chitosan &
Related Enzymes, ed. John P. Zikakis, Academic Press, 1984.
Specific metals mentioned were Cr, Mn, Fe, Cd, Co, Ni, Cu, Zn, and Hg.
Ammonium sulfate increases the collection rate.
The chelating effect is presumed to be because of electron donation by
free amino groups on the chitosan polymer, but other factors are
involved as well.
Ref 1: Muzzarelli, R., "Chitin", Pergamon Press (1977)
-- Jack Sullivan __________________ORGLIST - Organic Chemistry Mailing List Website and Archive: http://www.orglist.net/ List coordinator: Joao Aires de Sousa (jas$##$mail.fct.unl.pt)
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