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 FeCl _3 -activation of lotus seedpod. Simultaneous carbonization, activation, and magnetization formed magnetic Fe _3 O _4 nanoparticles and nanowires over the biochar base. The specific surface area (S _BET ) and the total pore volume (V _total ) of MBC were 349 m ^2 g ^−1 and 0.31 cm ^3 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 H _2 O _2 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.

Keywords

• lotus seedpod
• biomass valorization
• magnetic biochar
• catalytic oxidation
• Orange G