The adsorption and mechanism of U(VI) removal by β -cyclodextrin-functionalized magnetic biochar

In order to develop a highly efficient and magnetically recoverable uranium adsorption material, this study prepared β-cyclodextrin-modified magnetic biochar (β-CD@MFBC) composite and systematically investigated its adsorption performance for U(VI). The adsorption mechanism was explored using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy, Brunauer-Emmett-Teller (BET) analysis, vibrating sample magnetometry, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Results demonstrated that β-CD@MFBC exhibits a high specific surface area, unique mesoporous structure, and superparamagnetic properties. At pH 4.0 and 303.15 K, the maximum adsorption efficiency of 0.28 g·L⁻¹ β-CD@MFBC to 10 mg·L⁻¹ U (VI) was 99.46%, and the adsorption process was in accordance with the quasi-second-order kinetic model and Freundlich adsorption isotherm model, and the theoretical adsorption capacity reached 219.32 mg·g⁻¹. The U(VI) adsorption mechanism involves coordination between β-CD@MFBC's hydroxyl, carboxyl groups, and Fe/Mn-O complexes. Adsorption-desorption experiments confirmed the material's excellent reusability. These findings highlight the potential of β-CD@MFBC for treating U(VI)-contaminated wastewater.