The present study developed an alpha-ketoglutaric acid-modified magnetic chitosan (alpha KA-Fe3O4/CS) for highly efficient adsorption of Cd(II) from aqueous solution. Several techniques, including transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and vibrating sample magnetometer (VSM), were applied to characterize the adsorbent. Batch tests were conducted to investigate the Cd(II) adsorption performance of alpha-KA-Fe3O4/CS. The maximum adsorption efficiency of Cd(II) appeared at pH 6.0 with the value of 93%. The adsorption amount was large and even reached 201.2 mg/g with the initial Cd(II) concentration of 1000 mg/L. The adsorption equilibrium was reached within 30 min and commendably described by pseudo-second-order model, and Langmuir model fitted the adsorption isotherm better. Furthermore, thermodynamic parameters, free energy (Delta G), enthalpy (Delta H) and entropy (Delta S) of Cd(II) adsorption were also calculated and showed that the overall adsorption process was endothermic and spontaneous in nature because of positive Delta H values and negative Delta G values, respectively. Moreover, the Cd(II)-loaded alpha-KA-Fe3O4/CS could be regenerated by 0.02 mol/L NaOH solution, and the cadmium removal capacity could still be kept around 89% in the sixth cycle. All the results indicated that alpha-KA-Fe3O4/CS was a promising adsorbent in environment pollution cleanup. (C) 2013 Elsevier B.V. All rights reserved.