Efficient removal of Pb (II) by inexpensive magnetic adsorbents prepared from one-pot pyrolysis of waste tyres involved magnetic nanoparticles

•A novel magnetic carbonaceous adsorbent (MCA) derived from tyre rubber and Fe3O4 was prepared.•The surface characteristics of the MCA make them suitable for the adsorption of heavy metal ions.•The maximum adsorption capacity for Pb2+ is 66.84 mg·g−1, which is better than previous reports.•The MCA was low cost, high adsorption capacity, reusability, and easy recovery. A novel magnetic carbonaceous adsorbent (MCA) was prepared in low cost by pyrolysis of waste tyre rubber and corn flour with incorporated magnetic nanoparticles and used as an adsorbent to remove Pb2+ in aqueous solution. The powder of waste tyre rubber, the corn flour, and the magnetic nanoparticles were heated up to 500 ℃ at a heating rate of 10 ℃·min−1 and held isothermal for 30 min. The magnetic carbonaceous adsorbent (MCA-1050) prepared showed the maximum adsorption capacity of about 66.84 mg·g−1 for Pb2+ due to the existence of the –SH, −OH, and –COOH groups on its surface. The adsorption for Pb2+ reached the equilibrium within 50 min and the adsorption kinetics fitted to quasi–second–order kinetics equation. The adsorption thermodynamic process fitted better to the Langmuir isotherm equation than the Freundlich isotherm equation, indicating a monolayer adsorption process for Pb2+. Subsequently, in order to further learn the relationship between the structures of the carbonaceous adsorbents and pyrolysis conditions, the adsorbents were analyzed by Transmission Electron microscopy, Fourier–Transform Infrared Spectroscopy, X-ray photoelectron spectrometer, and Vibrating Sample Magnetometer. Finally, the MCA-1050 loaded with Pb2+ was eluted using EDTA solution (0.06 mol·L−1, pH 8.0), which showed good reusability and over 60% of removal rate was remained after 4 cycles.