This study investigated the degradation of perfluorooctanoic acid (PFOA) on zerovalent iron-laden biochar (BC-ZVI) prepared by carbothermal reduction. Results show that over 99% PFOA can be removed by BC-ZVI in hydrothermal conditions under 240 °C within 6 h. The maximum defluorination rate of 63.2% was achieved after 192 h, and this outcome was significantly better than biochar (BC) and zero-valent iron (ZVI) alone. The short-chain perfluorinated compounds (PFCs) and perfluoroheptanal were detected in the liquid phase after degradation, suggesting that the degradation of PFOAs by BC-ZVI followed the Kobel decarboxylation process. XRD and SEM-EDS analyses strongly suggested that carbothermal reduction could avoid the agglomeration of ZVI loaded onto biochar, which helped make the PFOA degradation more efficient. The frontier molecular orbital theory calculated by density functional theory revealed there were two possibilities for ZVI loading on BC (edged or internal loading), while the edge loaded ZVI had a greater tendency to provide electrons for the defluorination of PFOA than internally loaded ZVI.

本研究调查了全氟辛酸 (PFOA) 在通过碳热还原制备的含零价铁的生物炭 (BC-ZVI) 上的降解。结果表明，BC-ZVI 在 240 °C 的水热条件下可在 6 小时内去除 99% 以上的 PFOA。192 小时后达到 63.2% 的最大脱氟率，这一结果明显优于单独的生物炭 (BC) 和零价铁 (ZVI)。降解后在液相中检测到短链全氟化合物 (PFCs) 和全氟庚醛，表明 BC-ZVI 对 PFOA 的降解遵循 Kobel 脱羧过程。XRD 和 SEM-EDS 分析强烈表明碳热还原可以避免加载到生物炭上的 ZVI 团聚，这有助于使 PFOA 降解更有效。