A novel magnetic biochar from spent shiitake substrate: characterization and analysis of pyrolysis process

A novel magnetic biochar was obtained via pyrolysis of Fe(NO3) (3)-impregnated spent shiitake substrate (SSS). The product was characterized by X-ray diffraction (XRD), vibrating sample magnetometer (VSM), N-2-adsorption, scanning electron microscopy (SEM), and energy-dispersive Xray (EDX) analysis. The pyrolysis process was investigated by thermogravimetric analysis (TGA) and XRD, and the pyrolysis kinetic was analyzed via Coats-Redfern method. Experimental results demonstrated that the magnetic FeO center dot Fe2O3 crystals and porous char structure were effectively formed via pyrolysis, and the magnetic biochar had a saturation magnetization value of 20.83 emu/g. The product had a surface area of 177m(2)/g and a total pore volume of 0.188 cm(3)/g, respectively, and it consisted basically of micropores with diameter of 1.5 nm and mesopores with diameter between 2 and 10 nm. Moreover, Fe can decrease the thermal stability of SSS, and the magnetic crystals were mainly formed between the temperature region of 420 and 530 degrees C. In addition, the activation energy needed to break down the structure of SSS was lowered by 12.12 kJ/mol with the presence of Fe.