Preparation and characterization of a novel magnetic biochar for arsenic removal

► A magnetic biochar can be fabricated via pyrolysis of FeCl3 treated biomass. ► Colloidal or nanosized γ-Fe2O3 particles grow within biochar matrix. ► Biochar/γ-Fe2O3 composite has excellent ferromagnetic properties. ► Biochar/γ-Fe2O3 composite has strong sorption ability to As(V).