Interaction of heavy metals with chitin and chitosan. III. Chromium

Abstract The interaction of the natural marine polymer chitin and its deacetylated derivative chitosan with chromium has been investigated. The uptake of chromium from aqueous solution was determined from changes in concentration as measured by atomic absorption spectroscopy. The uptake of Cr(III) on chitosan was significantly greater than that on chitin. The smaller the size fraction of the chitin/chitosan, the greater the uptake of Cr(III). The Cr(III) uptake increased with increasing solution pH. Minimal desorption of chromium was observed on washing previously chromium‐equilibrated chitosan with distilled water. The uptake of Cr(III) by chitosan was enhanced in the presence of phosphate, whereas the converse was not observed. Minimal uptake of Cr(VI) as dichromate by chitin and chitosan was measured. Cr‐containing nodules were noted in the SEM/EDAX analysis for Cr(III)‐equilibrated chitosan. Cr‐containing clusters were detected for Cr(III)‐ plus phosphate‐equilibrated chitosan. XPS results supported the conclusions drawn from the isotherm studies.