Mesoporous magnetic biochar composite through one-pot hydrothermal process for efficient degradation of methylene blue dye by Fenton-like catalysis

This study investigates the synthesis of a new mesoporous magnetic biochar from the abundantly available Amaranthus stems via one-step hydrothermal carbonization. FESEM imaging revealed uniform dispersion of spherical clusters within the biochar matrix, while EDS confirmed the successful combination of biochar and iron-oxide. BET analysis showed a mesoporous structure (3.38 nm). XRD patterns indicated an amorphous biochar structure, with peaks corresponding to magnetite nanoparticles. VSM analysis demonstrated the superparamagnetism with a saturation magnetization of 35.43 emu/g. XPS analysis revealed Fe oxidation states with signals at 711.45 and 724.73 eV, confirming the successful synthesis and surface functionalization. Fenton-like catalytic removal of methylene blue (MB) dye resulted in rapid degradation and decolorization constants varying between 0.0096 and 0.0004 L/mg min across MB initial concentrations (5–25 ppm), fitting a second-order model. This work demonstrates a sustainable methodology to dye-laden aqueous streams, highlighting the capability of biochar-based magnetic nanocomposites for environmental remediation.