Effects of biomass pre-pyrolysis and pyrolysis temperature. on magnetic biochar properties

To evaluate the effects of biomass pre-pyrolysis and pyrolysis temperature on magnetic biochar (MB) properties, MB composites were fabricated from rattan sawdust (RS) and rattan charcoal (RC) through simple iron salt impregnation and subsequent pyrolysis under different temperatures (600-900 degrees C). Characterization analysis revealed that pyrolysis procedure greatly affects the physicochemical properties of final products. Magnetite dominates the crystal phases of the MB pyrolyzed at 600-800 degrees C and the Fe (III) species in MBS (MB from RS) are easier to be reduced into wustite. Raising the pyrolysis temperature to 900 degrees C or increasing the molar ratio of Fe2+-Fe3+ are effective ways to promote the formation of a-iron for both MBS and MBC (MB from RC). Although the MBS yield is lower than that of MBC, the magnetic media in MBS dispersed more uniform on the surface of the biochar matrix. The saturation magnetization decreased from 600 to 800 degrees C and increased afterward from 800 to 900 degrees C for MBS, which raised continuously for MBC.