Mechanochemical synthesis of biochar encapsulated FeMn nanoparticles with strong metal–carbon interactions for efficient degradation of tetracycline via activating peroxymonosulfate
Yue Wang, Zhenglong Liu, Pan Huang, Baoliang Lei, Lele Qiao, Tielong Li, Kun‐Yi Andrew Lin, Haitao Wang
Abstract
Transition metal and carbon nanomaterials are well-known for their peroxymonosulfate (PMS) activation capabilities. However, metal-based materials often suffer from ion leakage and poor reusability, while carbon-based materials have limited catalytic efficiency. To overcome these challenges and leverage the strengths of both, we introduce carbon-coated Fe/Mn composites (FeMn@BC), that establish strong interactions between metal components and the carbon substrate. FeMn@BC exhibited exceptional selectivity for 1 O 2 generation via PMS activation. In practical applications, FeMn@BC efficiently degraded tetracycline by activating PMS, achieving 99.1% removal in just 30 min. Importantly, FeMn@BC demonstrated remarkable stability, especially under visible light exposure. XPS analyses revealed strong interactions between FeMn components and the biochar shell, enhancing the electron transfer capacity of FeMn@BC through Fe(III)/Fe(II) and Mn(III)/Mn(II) redox pairs. In-situ attenuated total reflection Fourier-transform infrared (ATR-FTIR) analysis highlighted abundant hydroxyl groups in FeMn@BC as crucial active sites for electron transfer. Quenching experiments and electron paramagnetic resonance (EPR) measurements unveiled that FeMn@BC catalyzed 1 O 2 generation primarily through the disproportionation of O 2 − and energy transfer from oxygen vacancy to O 2 . Our work demonstrates the possibility of simple ball milling of biomass in the presence of iron salts for iron-catalyzed mechanochemical synthesis of biochar-based catalysts. This study not only presents a novel strategy for large-scale biochar-encapsulated transition metal catalyst synthesis but also explores the potential use of agricultural waste for value-added applications.