Magnetic biochar prepared by electromagnetic induction pyrolysis of cellulose: Biochar characterization, mechanism of magnetization and adsorption removal of chromium (VI) from aqueous solution

This work introduces a novel methodology for synthesis of magnetic biochar from cellulose using an electromagnetic induction technology. More rough surfaces, sharp corners and edges, and compact regular pore structure with Fe3O4 and Fe2O3 of magnetic biochar was obtained. Such magnetic biochar possessed higher specific surface area (~236 m2/g) and micropore volume (0.144 m3/g). More hydroxyl groups of magnetic biochars decomposed and reacted with iron ions to form new chemical bonds. The coercivity and remanence of two magnetic biochars were calculated to be 125.76 Oe and 1.26 emu/g, 71.48 Oe and 1.31 emu/g. The total iron leaching rate were 0.94% and 1.28%, indicating magnetic biochar form wet pyrolysis process showed strong magnetization and iron loading stability (98.59%). Alternating electromagnetic field influenced the iron loading capacity and stability by Lorentz force during wet pyrolysis process. Such magnetic biochar can be used for removal of Cr(VI) from wastewater.