Efficient and selective capture of uranium(VI) by MIL-125/MXene nanocomposites: Synergistic enhancement via...

The rapid development of the nuclear industry has made the efficient treatment of uranium-containing wastewater a significant challenge in environmental radiochemistry. This study aimed to develop a high-performance adsorbent for the removal of UO₂²⁺ from water. A series of MIL-125/Ti₃C₂ nanocomposites were successfully constructed via an in-situ solvothermal method, by integrating two-dimensional Ti₃C₂ MXene with rich surface functional groups and porous MIL-125(Ti) MOF. The composite material not only retained the regular pore structure of MIL-125 but also exposed a greater number of active sites, exhibiting optimal adsorption performance. Under neutral conditions (pH = 7), the adsorption of U(VI) onto MIL-125/Ti₃C₂-2 followed the pseudo-second-order kinetic model and reached equilibrium within 50 min, with a remarkable maximum adsorption capacity of 661.07 mg/g, clear superior to most reported adsorbents. The adsorption isotherm fitted the Langmuir model, indicating monolayer chemisorption. Furthermore, the material demonstrated excellent anti-interference ability and selectivity in the presence of various coexisting ions (except for Cu²⁺ and Ca²⁺) and humic acid, along with satisfactory regeneration performance (85.6% retention after 5 cycles). The adsorption mechanism involves strong coordination interactions between surface functional groups (-NH₂, -OH) and UO₂²⁺, while the potential reducing ability of MXene also facilitates the partial reduction of U(VI) to the more stable U(IV), forming a dual fixation mechanism of synergistic "adsorption-reduction". This work provides new insights and experimental evidence for designing efficient and stable MOF/MXene adsorbents for treating actual uranium-containing wastewater.