[Properties of chitosan and sorption of copper ions from a copper sulfate solution on chitosan]

The introduction of the paper briefly describes the properties of chitosan and the current utilization of the aminopolysaccharides chitosan, chitin, and their derivatives in pharmaceutical formulations, and in the health services also as sorbents of heavy metals and other substances. The degree of deacetylation (64%) of commercially produced chitosan was estimated from measured IR spectra, and spectrophotometry in the visible region was employed to study the kinetics and equilibrium of the Cu(II) ion sorption from CuSO4 aqueous solutions. Cu(II) sorption on the suspended chitosan was rather slow, it took 8-12 hrs to establish the sorption equilibrium, but the maximum determined sorption capacity, up to 200 mg of copper per 1 g of chitosan, greatly exceeded other adsorbents. A nearly stoichiometric ratio between the sorbed Cu(II) and the chitosan biopolymer structural units as well as decreasing sorption at lower pH (4-5) suggests complex formation of Cu(II) with the solid chitosan. The sorption was reversible, so the raw chitosan under study can be used as a high loading capacity carrier capable of the sorption and subsequent conditional liberation of a considerable amount of Cu(II) ions.