Magnetic carbon nanoadsorbents are widely applied in heavy metal decontamination, but the low adsorption capacities largely limit their practical uses. Herein, we reported the hydrothermal preparation of S doped Fe3O4 core-carbon shell nanoparticles (S-doped Fe3O4@C NPs) as recyclable adsorbent for Cu2+ removal. The adsorption capacity of S-doped Fe3O4@C NPs was over 54.7 mg/g, 10 times higher than that of active carbon, ranking S-doped Fe3O4@C NPs among the most effective adsorbents. The remnant Cu2+ concentrations were lower than 1.0 mg/L, which reached the criteria of drinking water. Moreover, S-doped Fe3O4@C NPs could be magnetically separated and easily regenerated after adsorbing Cu2+. (C) 2014 Elsevier B.V. All rights reserved.