BACKGROUND: Heavy metals present a great challenge due to pollution of the water environment. Conventional adsorption materials may be problematic for sustainable applications due to energy-intensive processing, low adsorption capacity and difficult liquid/solid separation. To address this issue, this study investigated monosaccharide biomass (i.e. glucose) as starting material for hydrothermal synthesis of carbon microspheres (CMS), followed by immobilization of magnetic iron oxide nanoparticles by a chemical co-precipitation method. RESULTS: The results demonstrated that the hydrothermal method could yield high-quality homogeneous carbon microspheres (0.2-0.6 mu m in diameter) with abundant oxygen-containing functional groups. The alkali treatment and chemical co-precipitation process produced magnetic Fe3O4 nanoparticles (10-20 nm) uniformly dispersed on the CMS surface. The MCMS exhibited effective adsorption of Cd(II) ions in water, which was consistent with quasi-second-order kinetics and Langmuir isotherms. On reaching adsorption equilibrium, the MCMS could be separated from the liquid phase instantly and completely in the presence of an applied external magnetic field gradient. CONCLUSION: The MCMS synthesized by a hydrothermal and co-precipitation method show great promise as a new sustainable carbon-based adsorbent for potential application in the elimination of heavy metals from water and wastewater. (C) 2013 Society of Chemical Industry