To improve the xanthogenic acidification efficiency of chitosan (CTS), a novel chitosan-based adsorbent (XMCTS) with strong chelating ability was prepared by using maleic anhydride as the connecting bridge for the first time. Some characterization methods such that scanning electron microscope, nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric were employed to analysis the structure of copolymers, and verify the successful synthesis of XMCTS. Comparative study found that the introduction of maleic anhydride increased the graft rate and acid stability of XMCTS. Impact of dosage, pH, contact time, initial concentration, and temperature on adsorption performance were explored. Compared with CTS, XMCTS showed better adsorption performance, reaching a maximum of 201.43 mg/g at 40 C. The adsorption kinetics of XMCTS fitted well with the pseudo-second-order model, and the adsorption isotherm was well described by the Langmuir isotherm model. Adsorption thermodynamics indicated that the adsorption of Cu(II) was a spontaneous endothermic process. The analysis of adsorption mechanism indicated that the strong synergistic chelation and electrostatic attraction of the amino, carboxyl, hydroxyl and xanthate groups contributed to the adsorption of Cu(II) effectively. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.