Efficient removal of metribuzin from water using modified beet molasses biochar: Adsorptive performance and mechanism

This study employed KOH-modified beet molasses biochar (MBCK) for the effective removal of metribuzin (MB) from wastewater. The adsorption behavior and mechanisms were investigated through the application of kinetic and isotherm models, thermodynamic analyses, a range of characterization techniques (SEM, BET N₂, FTIR, XPS, etc.), and density functional theory (DFT) calculations. The results indicate that MBCK achieved a maximum adsorption capacity of 79.45 mg/g and a removal efficiency of 99.31% within 1 h. Characterization analyses revealed that KOH modification significantly increased the biochar's specific surface area (up to 3691.710 m 2 /g), which is 4.17 times that of the unmodified sample. MBCK maintained high removal efficiency (> 98%) over a wide pH range (3−11) and in various real water matrices (lake, river, rain, and tap water), demonstrating excellent environmental adaptability and stability. Furthermore, MBCK was effectively regenerated via ethanol desorption, retaining 94.57% of its removal efficiency after three adsorption–desorption cycles, highlighting its sustainable adsorption potential. Moreover, MBCK maintains a considerable adsorption capacity for atrazine while removing metribuzin, further enhancing its potential for practical wastewater treatment applications. The primary contributor to the adsorption of metribuzin by MBCK is pore filling, followed by electrostatic interactions, hydrogen bonding, and π–π stacking. Overall, this study provides a novel approach for the high-value utilization of beet molasses and an eco-friendly and facile strategy for efficiently removing pesticides such as metribuzin from real water environments.