Enhancement of the metal-binding properties of chitosan through synthetic addition of sulfur- and nitrogen-containing compounds

Several new chitosan derivatives were synthesized with the intent of forming polymers that could be used in hazardous waste remediation as toxic metal-binding agents in aqueous environments. The ability of these derivatives to bind Cu²⁺, Pb²⁺, Cd²⁺, and Fe²⁺ was tested and compared to chitosan. Four of the new compounds, the products of the reaction of chitosan with mercaptosuccinic acid, thiirane, pyridoxal hydrochloride, and succinamide, show promising results as binding agents for the above metal ions. The compound with mercaptosuccinic acid bound twice as much Cd²⁺, five times as much Pb²⁺, and virtually no Fe²⁺ when compared to chitosan. The compound with thiirane bound three times as much Pb²⁺, whereas the pyridoxal hydrochloride derivative bound 30% more Cu²⁺ and twice the Pb²⁺. The succinamide derivative gave results comparable to chitosan, but with decreased solubility at low pH. © 1993 John Wiley & Sons, Inc.