Preparation of MXene/SA gel microspheres and its adsorption performance for U(VI)

In order to improve the adsorption capacity and recyclability of the nanomaterial MXene, sodium alginate (SA) and MXene were mixed by ion cross-linking method to fix the Ti₃C₂T_x MXene nanomaterial on the SA aerogel matrix. After freeze-drying, MXene/SA gel microspheres was prepared. The structure of the gel microspheres was characterized by SEM-EDS, FTIR and XPS, and the adsorption characteristics of MXene/SA gel microspheres to uranium (VI) in aqueous solution were investigated under the influence of different factors, and its recycling ability was explored. The results show that the adsorption of uranium by MXene/SA gel microspheres follows the pseudo-second-order kinetics and Langmuir isotherm adsorption model, indicating that the adsorption is mainly monolayer chemical adsorption, and the thermodynamic parameters indicate that the adsorption process is a spontaneous endothermic. When the pH is 4 and the temperature is 298 K, the maximum adsorption capacity of MXene/SA gel microspheres for uranium is 126.82 mg·g⁻¹. The main adsorption mechanism is ion exchange and complexation. More importantly, after 5 cycles of the gel microspheres, the removal rate remains above 90%, indicating that the adsorbent has the performance of recycling and reuse and will not cause secondary pollution to the water environment. Therefore, MXene/SA gel microsphere adsorbent has shown great potential in repairing the pollution of radionuclide uranium wastewater.