Synthesis and characterization of rice husk-based magnetic porous carbon by pyrolysis of pretreated rice husk with FeCl3 and ZnCl2

[Display omitted] •Rice husk-based magnetic porous carbon with SBET > 1000 m2/g was obtained.•Optimal ZnCl2 impregnation ratio and pyrolysis temperature were 1.0 and 600 °C.•Combined pretreatment and simultaneous activation and magnetization was confirmed. Rice husk-based magnetic porous carbon with high porosity and magnetization was synthesized by pyrolysis of pretreated rice husk with FeCl3 and ZnCl2. Thermogravimetric analyses (TGA) of the precursors were used to characterize the mechanism of the pyrolysis progress. The effects of ZnCl2 impregnation ratio and pyrolysis temperature on the properties of magnetic porous carbon were identified by ultimate analyses, scanning electron microscopy (SEM), N2 adsorption-desorption isotherms, X-ray diffractometer (XRD), Raman spectrometer and vibrating sample magnetometer (VSM). Based on the results, the optimum ZnCl2 impregnation ratio of 1.0 and pyrolysis temperature of 600 °C were obtained when considering both of the porous characteristics and magnetic properties. Finally, the synergistic effect of combined pretreatment of hydrothermal carbonization (HTC) and alkali leaching and simultaneous activation and magnetization was confirmed as the possible reaction mechanism of synthesis of magnetic porous carbon from rice husk with the surface area of 1344.67 m2/g and saturation magnetization of 3.64 emu/g.