Defective UiO-66 for the highly efficient elimination of U(V) from wastewater: Insights to the effects of defects and pore structure on the adsorption process

A defective metal-organic framework UiO-66-18 synthesized via a facile solvothermal synthesis method with trifluoroacetic acid as modulator was demonstrated to be highly efficient for the elimination of uranium from wastewater. The maximum adsorption capacity of UiO-66-18 toward uranium reached 622.75 mg g-1, which was approximately 1.43 times higher than that of pristine UiO-66-0 prepared without TFA modulation. The superior elimination performance of UiO-66-18 was because the TFA modulation induced the generation of more missing -linker defects that endowed UiO-66-18 with hierarchical structure and more adsorption active sites for U (VI) capture. Further adsorption mechanism studies indicated that the elimination of U(VI) was endothermic monolayer chemisorption dominated by mass transfer-decomplexation-adsorption process. In addition, the effects of common ions on the elimination efficiency as well as the reusability of UiO-66-0 and UiO-66-18 were studied. This work provides a promising strategy and a theoretical basis for the design and preparation of efficient uranium adsorbent from the points of defects engineering and pore structure design.