Theoretical insights into the uranyl adsorption behavior on vanadium carbide MXene

Remediation of the contamination by long-lived actinide wastes is extremely important but also challenging. Adsorption based techniques have attracted much research attention for their potential as low-cost and effective methods to reduce the radioactive waste from solution. In this work, we have investigated the adsorption behavior of uranyl species [with the general form UO2(L-1)(x)(L-2)(y),(L-3)(z), where L-1, L-2 and L-3 stand for ligands H2O, OH and CO3, respectively] on hydroxylated vanadium carbide V2C(OH)(2) MXene nanosheets using density functional theory based simulation methods We find that all studied uranyl species can stably bond to hydroxylated MXene with binding energies ranging from -3.3 to -4.6 eV, suggesting that MXenes could be effective adsorbers for uranyl ions. The strong adsorption is achieved by forming two U-O bonds with the hydroxylated Mxene. In addition, the axial oxygen atoms from the uranyl ions form hydrogen bonds with the hydroxylated V2C, further strengthening the adsorption. We have also investigated the effects of F termination on the uranyl adsorption properties of V2C nanosheets. U-F bonds are in general weaker than U-O bonds on the adsorption site, suggesting that F terminated Mexne is less favorable for uranyl adsorption applications. (C) 2017 Elsevier B.V. All rights reserved.