Quantitative Determination of Heavy Metal Contaminant Complexation by the Carbohydrate Polymer Chitin

Chitin is a cost-efficient and nontoxic biopolymer with potential for use in heavy metal chelation from industrial wastewater. In this study we report the binding strength of chitin and the common water contaminants mercury, copper, iron, nickel, chromium, lead, zinc, cadmium, silver, and cobalt. We have found that the strongest binding takes place with mercury and weakest with cobalt with binding constants of 1.16·105 M−1 and 3.96·103 M−1, respectively. We observed that the formal charge state of the heavy metal inversely affects the binding strength. The divalent metal cation−chitin interactions are all enthalpically driven binding reactions. These results serve to benchmark industrial wastewater treatment by chitin chelation.