One-pot fabrication of magnetic biochar by FeCl3-activation of lotus seedpod and its catalytic activity towards degradation of Orange G

Abstract

An advanced magnetic biochar (MBC) was facilely prepared via one-pot FeCl3-activation of lotus seedpod. Simultaneous carbonization, activation, and magnetization formed magnetic Fe3O4 nanoparticles and nanowires over the biochar base. The specific surface area (SBET) and the total pore volume (Vtotal) of MBC were 349 m2 g−1 and 0.31 cm3 g−1, which were 2.0-fold and 3.9-fold higher than those of biochar, respectively. In addition, the saturation magnetization of MBC reached 6.94 emu g−1, facilitating its magnetic separation and recovery. In heterogeneous Fenton-like catalytic oxidation, 0.40 g l−1 MBC decolorized 100% Orange G and reduced 58% COD by 350 ppm H2O2 within 120 min. The degradation kinetics were calculated with different MBC samples and reactions followed pseudo-first-order kinetics with the highest rate constant of 0.034 min−1. Moreover, the catalytic activity dropped by only 6.4% after four reuse cycles, with negligible iron leaching of 1.31–1.44 mg l−1. Based on these results, MBC could be a low-cost, highly effective, and relatively stable catalyst for treating Orange G in wastewater.