, which was approximately 70 % higher than that of the metal-free control (O/BC) and exceeded that of most reported biochar-based adsorbents. Moreover, Fe-O/BC maintained high efficiency over a wide pH range (3-9) and exhibited good tolerance to cations, anions, and real water matrices, indicating its strong adaptability to environmental conditions. Pore filling and π-complexation were identified as the main adsorption mechanisms. Consequently, Fe-O/BC exhibited excellent adsorption performance toward most other aromatic organics. In-depth analysis of electron transfer indicated that O-coordination promoted d-π* back-donation by acting as an electron donor or "electron bridge", thereby enhancing the π-complexation activity of the Fe sites. This work provides new insights into how O-coordination regulates the adsorption activity of Fe sites and enables the development of advanced biochar-based adsorbents for pollutant control.
Zhu et al. (Tue,) studied this question.