Preparation of CeO2/biochar composites by flash Joule heating and the research on its efficient removal performance of VOCs

Abstract

Volatile organic compounds (VOCs) are hazardous air pollutants that pose significant risks to human health and the environment. In this study, CeO₂-loaded biochar composites (CeO₂@BC-J) were rapidly synthesized via flash Joule heating (FJH), using wheat straw as the carbon source. The resulting composites exhibited a high specific surface area (160.04 m²·g⁻¹), uniform CeO₂ dispersion, and enhanced porosity. Fixed-bed adsorption tests showed that CeO₂@BC-J achieved a toluene adsorption capacity of 301.24 mg·g⁻¹, far surpassing its conventionally prepared counterpart (CeO₂@BC-G). Kinetic and isotherm analyses revealed a dual adsorption mechanism involving both physisorption and chemisorption. In situ DRIDTS spectra showed the emergence of CO and CO bonds during toluene adsorption, confirming surface oxidation reactions. Density functional theory (DFT) calculations and charge density difference analysis further demonstrated electron transfer from toluene to CeO₂, accompanied by Ce⁴⁺ reduction to Ce³⁺ at oxygen vacancy sites. This study not only demonstrates the effectiveness of FJH in constructing high-performance VOCs adsorbents, but also provides mechanistic insights into redox-enhanced adsorption pathways.