Cross-Linked Chitosan Spheres and Magnetic Composites for Adsorption of Heavy Metals and Catalysis

The paper presents the results of a study of the adsorption properties chitosan (CS) spheres cross-linked with epichlorohydrin (ECH). During the study, a procedure was developed for obtaining and cross-linking of CS spheres, as well as CS-based magnetically separable composites. The adsorption capacity of CS-ECH spheres was tested by the example of aqueous solutions of Ni2+ and Cr2O72- with different concentrations. It was shown that in a batch mode the adsorption equilibrium in the case of Ni2+ was achieved in 60 min, whereas in the case of Cr2O72- a longer time was required (420 min or more). It was found that CS-ECH spheres can accumulate about 3 wt.% Ni2+ and up to 10 wt.% of Cr6+ ions. Magnetically separable composites (Fe3O4-CS-ECH) were found to provide higher efficiency of adsorption in comparison with CH-ECH. Moreover, the catalyst Pd/CH-ECH was synthesized and tested in hydrogenation of nitrobenzene at ambient pressure.