Magnetic oak wood biochar (MOWBC) and magnetic oak bark biochar (MOBBC) were obtained from oak wood and oak bark biochars made by fast pyrolysis during bio-oil production. These were investigated as potential green adsorbents for cadmium and lead remediation from water. Biochars were obtained from fast pyrolysis at 400 and 450 degrees C in an auger-fed reactor and then magnetized by mixing aqueous biochar suspensions with aqueous Fe3+/Fe2+ solutions, followed by treatment with NaOH. The compositions and surface chemistries of these magnetic biochars were examined by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM), energy-dispersive X-ray spectroscopy (EDXRF), BET surface area (S-BET), energy-dispersive-X-ray-fluorescence analysis (EDXRF), point of zero charge (pH(PZC)), density and magnetic moment determinations. The S-BET of the magnetic oak wood and bark chars were 6.1 and 8.8 m(2) g(-1), respectively. Batch sorption studies were performed at 25-45 degrees C, pHs of 2-7 and different solid-to-liquid ratios. Maximum lead and cadmium removal occurred at pH 4-5. Sorption isotherms over a concentration range of 1-100 mg/L exhibited increasing metal ion removal as temperature went up with both magnetic wood and bark biochars. Sorption performances at 25, 35 and 45 degrees C were evaluated using the Freundlich, Langmuir, Redlich-Peterson, Toth, Sips, Radke and Prausnitz and Koble-Corrigan adsorption isotherm models. Kinetic data were better fitted by second order kinetic model. Lead and cadmium were successfully remediated from water using magnetic biochar. These magnetic biochars remediated Pb2+ and Cd2+ better than their corresponding nonmagnetic biochars previously reported, adsorbing more metal ions than expected based on their S-BET values. They were easily manipulated by low external magnetic fields, permitting their easy separation from the aqueous-phase. Magnetic filtration requires no gradient and therefore no separation system fouling occurs, allowing convenient adsorbent cleaning, recycle or replacement from contaminated water. (C) 2013 Elsevier B.V. All rights reserved.