Sorption of Copper(ii) Ions by Composite Sorbent Based on Chitosan

Composite sorbents based on chitosan containing silica, Jerusalem artichoke powder, and carbon nanotubes were developed for the extraction of heavy-metal ions from aqueous solutions. The equilibrium and kinetics of Cu(II) ion removal in the heterogeneous system "aqueous metal sulfate solution - sorbent" were investigated for both the initial chitosan powder and the modified sorbents obtained in the form of hydrogel granules. The kinetic experiments established the time required to reach sorption equilibrium and identified the kinetic model that most accurately describes the process. The experimental sorption isotherms demonstrate a significant increase in the sorption capacity of the chitosan-based composites compared with the unmodified material. Processing the Cu(II) sorption isotherms using the Langmuir model allowed determination of the maximum sorption capacities (A). It was found that A for the chitosan/silica/Jerusalem-artichoke composite and for the chitosan/carbon-nanotube composite substantially exceeds that of the original chitosan. Changes in the sorbent composition resulting from modification are confirmed by IR-spectroscopic data. SEM studies show a well-developed surface structure of the composite chitosan-based hydrogel granules.