Simultaneous elimination of U(VI) and Eu(III) by phytic acid decorated MXenes@MOFs composites in water: Performance, kinetics and mechanism

The efficient removal of radionuclides from nuclear wastewater was of great importance for environmental protection. Herein, the MXene Nb3C4 was first composited with UiO-66-NH2 via ultrasonic self-assembly, followed by modifying the surface of the composite with phytic acid to construct Nb3C4@UiO-66-NH2-PA, which was used as an adsorbent for remediation of radionuclides. Spectral analysis and batch experiments showed that the high specific surface area and abundant functional groups made a great contribution to the simultaneous elimination of U(VI) and Eu(III) from aqueous solution by Nb3C4@UiO-66-NH2-PA. The developed adsorbent exhibited maximum capture capacities of 725.8 mg/g for uranium(VI) and of 368.1 mg/g for europium(III), respectively, and the elimination process happened on monolayer and was controlled by chemisorption. Meanwhile, the competitive adsorption demonstrated that no effect of the coexisting cations on capture of tar -geted pollutants, while the derived thermodynamic parameters revealed that the adsorption process was endothermic and spontaneous. This adsorbent also kept an excellent adsorption ability after three adsorption-desorption cycles. Finally, the characterization analysis manifested that the interaction mechanism of radionuclides on Nb3C4@UiO-66-NH2-PA was related to the surface complexation and electrostatic attraction between radionuclides and the functional groups (-NH2, P-OH, and -OH). Thus, this research would offer a theoretical guidance to radioactive drainage management and radioactive wastewater remediation.