Renewable Tb/Eu-Loaded Garlic Peels for Enhanced Adsorption of Enrofloxacin: Kinetics, Isotherms, Thermodynamics, and Mechanism

摘要

Environmentally friendly terbium, europium, and terbium/europium-loaded garlic peels (Tb@GP, Eu@GP, and Tb/Eu@GP) were successfully synthesized and evaluated as biosorbents for the extraction of enrofloxacin (ENR) from aqueous solutions. Notably, it was found that the adsorption capacity of Tb/Eu@GP (769 mg g(-1)) for enrofloxacin was significantly enhanced compared with unloaded GP (29.8 mg g(-1)) and was superior over Tb@GP (580 mg g(-1)) and Eu@GP (421 mg g(-1)). The high adsorption capacity of Tb/Eu@GP reflected the efficiency and cost effectiveness of the adsorption process. In order to gain insight into the modification method and adsorption behaviors, Tb@GP, Eu@GP, and Tb/Eu@GP were fully characterized, and their adsorption kinetics, isotherms, and thermodynamics were investigated. Additionally, Tb/Eu@GP was found to be highly efficient at pH values ranging from 6.0 to 8.0. Besides, ultrapure water containing 5% ammonia could elute 98.1 +/- 1.5% of the absorbed ENR from Tb/Eu@GP, and the reusability and regeneration test also revealed the sustainability of Tb/Eu@GP. Moreover, XPS analysis confirmed ligand exchange between the hydroxyl and the fluorine group of enrofloxacin might be the main mechanism in the adsorption process. This work demonstrated loading terbium and europium on agricultural byproduct could be a potential method for developing cost-effective and eco-friendly biosorbents for fluoroquinolones.