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Given the persistent environmental and non-target organismal threats posed by imazethapyr, there is an urgent need to develop an efficient adsorbent material for the removal of residual imazethapyr. In this study, a Fe-Mg co-modified biochar (MFBC700) was synthesized by impregnating maize stover with FeCl₃·6H₂O and MgCl₂·6H₂O followed by pyrolysis at 700°C for imazethapyr adsorption. The results demonstrated that MFBC700 possessed a large specific surface area (285.25 m²/g), abundant surface functional groups, and a high adsorption capacity of 63.16 mg/g, which was 3.14 times higher than that of unmodified biochar (BC700). The adsorption process of imazethapyr on MFBC700 adhered to the pseudo-second-order kinetic model and the Freundlich isotherm model. Thermodynamic analyses indicated that the adsorption process of imazethapyr by MFBC700 was spontaneous, endothermic, and characterized by increased randomness. Density functional theory (DFT) calculations further revealed that -C=O, -CO-Fe, and -CO-Mg groups played critical roles in imazethapyr adsorption. The adsorption mechanisms involved complexation, hydrogen bonding, π-π interactions, electrostatic adsorption, and pore filling. Additionally, MFBC700 exhibited strong anti-interference properties and excellent reusability during the adsorption process, underscoring its broad application potential.
Fan et al. (Sat,) studied this question.