Microwave preparation and properties of O‐crosslinked maleic acyl chitosan adsorbent for Pb2+ and Cu2+

A novel chitosan‐based adsorbent (CCTM) was prepared by the reaction of epichlorohydrin O‐crosslinked chitosan with maleic anhydride under microwave irradiation. The chemical structure of this polymer was characterized by infrared spectroscopy and X‐ray diffraction analyses. The effects of various variables such as degree of substitution, adsorption time, initial metal ion concentration, solution pH, and temperature, on the adsorption of Pb2+ and Cu2+ by CCTM were investigated. The results demonstrate that the microwave irradiation can remarkably enhance the reaction. CCTM has higher adsorption capacity than chitosan. The maximum adsorption capacities for Pb2+ and Cu2+, with initial concentrations of 0.02 mol L−1 at pH 5, are 246.3 and 132.5 mg g−1, respectively. The adsorbent can be recycled. These results have important implications for the design of effective chitosan‐based adsorbents in the removal of heavy metal ions from wastewaters.