Synthesis of magnetic biochar composite using Vateria indica fruits through in-situ one-pot hydro-carbonization for Fenton-like catalytic dye degradation

The present study reports the synthesis, characterization, and application of sustainable magnetic biochar composite. The inedible fruits of Vateria indica, a powerful ayurvedic plant were hydrothermally transformed into magnetic biochar (BC–Fe₃O₄) in a single step and characterized by several sophisticated techniques. FESEM analysis portrayed fibrous irregular mesh-like biochar with surface clustered Fe₃O₄ nanoparticles, while the incidence of carbon, oxygen, and iron in the elemental analysis by EDS established magnetic biochar formation. Numerous peaks consistent with planes of (220), (311), (400), (422), (511), (440), and (120) also substantiated the occurrence of magnetite nanoparticles and biochar respectively, as analyzed by XRD. XPS analysis showed signals at 285.65 eV, 533.28 eV, 711.08 eV, and 724.68 eV corroborating a strong C–O bond, O1s orbit, Fe²⁺, and Fe³⁺ respectively. BC–Fe₃O₄ was superparamagnetic with saturation magnetization of 4.74 emu/g, as per VSM studies, while its specific surface area, pore volume, and pore diameter were 5.74 m²/g, 0.029 cm³/g, and 20.86 nm respectively. The Fenton-like degradation of methylene blue (5.0–25.0 ppm) was accomplished by synthesized BC–Fe₃O₄, in the presence of H₂O₂. Within 180 min, almost complete degradation was achieved, with first-order kinetics having rate constants between 0.0299 and 0.0167 min⁻¹. Stability and recyclability studies performed over 7 cycles exhibited unaltered degradation between 93.98 and 97.59%. This study exhibits the exceptional characteristics and degradation capabilities of BC–Fe₃O₄ synthesized from a sustainable plant biomass.