(2026) Journal of Water Process Engineering_CO₂-assisted synthesis of Fe/N-doped biochar for efficient Fenton-like process

Lee Y.-J.; Lee J.; Weon S.; Park S.-J.; Kwon E.E.

(Elsevier Ltd) Journal of Water Process Engineering ISSN: 22147144 Vol.87 Issue. Article No.110048 DOI: 10.1016/j.jwpe.2026.110048

Persulfate (PS)-based Fenton-like process is effective for degrading organic pollutants in aqueous systems. Given that iron is earth abundant and inexpensive, Fe-loaded biochar has attracted particular attention as a PS-activating catalyst. However, mass production of Fe-loaded biochar is hindered by the low energy recovery from the conventional pyrolysis process. Here, Fe-impregnated rice husk (RH) was pyrolyzed under CO₂ to convert condensable oxygenated compounds (derived from RH) into syngas. Time-resolved gas evolution (CO, H₂, CH₄, and C₂ hydrocarbons (HCs)) showed that Fe species enhanced the formations of CO and H₂ from CO₂-assisted pyrolysis of Fe-impregnated RH. The reduced abundance of oxygenated compounds in bio-oil indicated an enhanced conversion of condensable volatiles into syngas. For Fe-loaded biochar synthesized under the CO₂ condition (Fe/RHB_CO₂), its characterizations confirmed the immobilization of Fe₃O₄ active sites, an increased mesopore volume, and enrichment of N functionalities within the structure of biochar. Consequently, Fe/RHB_CO₂ exhibited higher bisphenol A adsorption capacity and superior peroxydisulfate/peroxymonosulfate activation compared with Fe-free RHBs prepared under N₂ or CO₂, achieving >99% BPA removal. By linking energy-efficient catalyst production with effective organic pollutant degradation, this work outlines a practical route to couple biomass valorization with advanced water-treatment processes. © 2026 Elsevier Ltd.

This work was supported by the National Research Foundation of Korea (NRF) grants funded by the Korean Government ( MSIT ) (Grant No. RS-2023-NR077231 ).