Efficient extraction of radionuclides with MXenes/persimmon tannin functionalized cellulose nanofibers: Performance and mechanism

A bio-adsorbent (DACNF-MXenes-NH2-PT) was facilely prepared by introducing persimmon tannin (PT) and amino-functionalized MXenes (MXenes-NH2) into dialdehyde cellulose nano-fibres (DACNF) through cross-linking reaction. The advanced spectroscopy techniques confirmed that the bio-adsorbent possessed fibrous structure, abundant active groups (TiOH, ArOH and NH2) and high chemical stability. Batch experiments showed that water environmental condition played a vital roles in elimination process, and DACNF-MXenes-NH2-PT possessed a high uptake amounts towards U(VI) (105.7 mg/g) and Th(IV) (95.1 mg/g). Meanwhile, the equilibrium studies specified that adsorption data followed the Langmuir and Pseudo-second-order models, which implied that extraction process mainly depended on sharing of electrons between bio-adsorbents and adsorbates. More importantly, the competitive adsorption studies found that DACNF-MXenes-NH2-PT had a selective affinity for U(VI)/Th(IV), while its removal efficiency exhibited slightly decrease after three adsorption–desorption cycles. The characterization analysis revealed that the elimination of radionuclides mainly depended on the strong coordination, complexation and the synergetic effect of surface adsorption and intercalation adsorption. Thus, the unique bifunctional ability of DACNF-MXenes-NH2-PT would provide a new way for the treatment of radioactive wastewater in the future.