Optimization of Preparation Conditions and Characterization of Biochar-Supported Nanoscale Zero-Valent Iron Materials

Abstract

Tetracycline is a widely used antibiotic worldwide, and its residues in aquatic environments can cause persistent pollution, affect the ecological balance, and be harmful to human health. Fenton-like reaction is a commonly used advanced oxidation method for removing refractory organic pollutants, while nano-zero valent iron is a commonly used and efficient catalyst. In this study, biochar-nano zero valent iron (BC-nZVI) composite materials were prepared from food waste and peanut shells by liquid phase reduction method to construct a BC-nZVI+H₂O₂ Fenton-like system for the degradation of tetracycline in water. The degradation performance of the system, the influence of various experimental conditions, the reaction mechanism, and the catalytic performance and stability of BC-nZVI were investigated. Results of electron paramagnetic resonance (EPR) indicated that hydroxyl radicals were produced in the reaction process, and the material had high catalytic efficiency for hydrogen peroxide. The reaction order n for the decomposition of hydrogen peroxide was 1.0709, and the reaction rate constant k=0.1243 min^-1. BC-nZVI materials mainly degraded tetracycline through the synergistic effects of physical adsorption, chemical reduction, and catalytic degradation. The BC-nZVI+H₂O₂ Fenton system had a high degree of mineralization of tetracycline, with a TOC removal rate of 81.63%. Tetracycline was oxidized and hydroxylated under the action of free radicals in the medium, followed by demethylation and methylamino group removal, further ring opening, and degradation into small molecular intermediate products, which eventually decomposed into CO₂ and H₂O.