Review on preparation and adsorption properties of chitosan and chitosan composites

Compared with traditional polymers, biopolymers are more environmentally friendly due to their sustainable sources, easy decomposition and naturally recycled by biological processes. Among all biopolymers, chitosan (CS) proves attractive for several adsorption-related applications such as in gas capture and removal of dyes or heavy metal ions. However, there are considerable drawbacks such as unstable yield, non-uniform sizes, lack of process repeatability, low mechanical strength and chemical resistance. Thus, physical and chemical modifications have been proposed to obtain stable size and improved mechanical property of CS beads, microspheres, film or fiber. This paper introduces the research background of CS and modified CS as an adsorbent and analyzes the modification, application and adsorption mechanism of CS and CS composite materials. The research progress of the adsorption of metal ions, dyes and anions by CS and CS composite materials is reviewed, and the main factors affecting their adsorption performance are summarized. Finally, the development trend of CS as adsorbents is prospected.