Mesoporous magnetic MXene/MgFe-LDH composite for efficient oxytetracycline removal from wastewater: structural...

Oxytetracycline (OTC), a broad-spectrum antibiotic, is a critical emerging contaminant widely detected in global surface waters, where its persistence promotes antimicrobial resistance and disrupts aquatic ecosystems by inhibiting photosynthesis in plants even at trace levels. To address this challenge, a novel mesoporous Fe₃O₄@MXene/MgFe-LDH composite was synthesized under ambient conditions via sequential MXene delamination, MgFe-LDH hybridization, and magnetization. The physicochemical properties of the material were characterized using XRD, FT-IR, XPS, TGA/DTA, TEM, FE-SEM/EDS, VSM, and nitrogen adsorption-desorption analyses. The composite exhibited a high specific surface area (134.54 m²/g) and demonstrated excellent performance in removing OTC from wastewater. The effects of adsorbent mass, solution pH, ionic strength, phase contact time, initial OTC concentration, and temperature on the adsorption efficiency were systematically investigated using LC-MS/MS analysis. The results showed that the Fe₃O₄@MXene/MgFe-LDH composite achieved a high OTC removal efficiency of up to 99% within 30 min, with a maximum adsorption capacity of 238.1 mg/g based on pseudo-second-order kinetic model and the Langmuir isotherm, indicating monolayer adsorption. Thermodynamic analysis confirmed that the adsorption process was spontaneous and endothermic. Moreover, the adsorbent exhibited strong regeneration capability in recyclability tests and achieved 96% and 99% OTC removal in real veterinary clinic (1663 μg/L) and livestock farm (117 μg/L) wastewaters, confirming its practical applicability.