Efficient Capture of Perrhenate and Pertechnetate by a Mesoporous Zr Metal–Organic Framework and Examination of Anion Binding Motifs

Abstract

At the Hanford Site in southeastern Washington state, the U.S. Department of Energy intends to treat 56 million gallons of legacy nuclear waste by encasing it in borosilicate glass via vitrification. This process ineffectively captures radioactive pertechnetate (TcO4 –) because of the ion’s volatility, thereby requiring a different remediation method for this long-lived (t 1/2 = 2.1 × 105 years), environmentally mobile species. Currently available sorbents lack the desired combination of high uptake capacity, fast kinetics, and selectivity. Here, we evaluate the ability of the chemically and thermally robust Zr6-based metal–organic framework (MOF), NU-1000, to capture perrhenate (ReO4 –), a pertechnetate simulant, and pertechnetate. Our material exhibits an excellent perrhenate uptake capacity of 210 mg/g, reaches saturation within 5 min, and maintains perrhenate uptake in the presence of competing anions. Additionally, experiments with pertechnetate confirm perrhenate is a suitable surrogate. Single-crystal X-ray diffraction indicates both chelating and nonchelating perrhenate binding motifs are present in both the small pore and the mesopore of NU-1000. Postadsorption diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) further elucidates the uptake mechanism and powder X-ray diffraction (PXRD) and Brunauer–Emmett–Teller (BET) surface area analysis confirm the retention of crystallinity and porosity of NU-1000 throughout adsorption.

99TcO4− removal from legacy defense nuclear waste by an alkaline-stable 2D cationic metal organic framework

“…3c , the sorption isotherm curves plotted by the equilibrium concentration against the ion-exchange capacity q (mg/g) are fit well with the Langmuir model and the maximum anion-exchange capacity ( q m ) was calculated to be 318 ± 8 mg/g (Supplementary Tables 3 and 4 ). This greatly exceeds the capacity of Yb 3 O(OH) 6 Cl (48.6 mg/g) 49 , NDTB-1 (49.4 mg/g) 49 , UiO-66-NH 3 + (159 mg/g) 48 , NU-1000 (210 mg/g) 47 , SCP-IHEP-1 (211 mg/g) 46 , SCU-101 (247 mg/g) 42 , and SCU-102 (291 mg/g) 45 , but is lower than those of SCU-CPN-1 (999 mg/g) 21 , SCU-100 (541 mg/g) 16 , SLUG-21 (602 mg/g) 39 , PAF-1-F (420 mg/g) 59 .…”

Atomic‐ and Molecular‐Level Design of Functional Metal–Organic Frameworks (MOFs) and Derivatives for Energy and Environmental Applications

“…The uptake capacities possessed clear dependence on the number of defect sites (i.e., not occupied by structural ligands). The capture of pertechnetate (TcO 4 − ) and perrhenate (ReO 4 − ) was shown to occur by a pseudo‐ion exchange mechanism at the hydroxyl or water‐capped sites in the Zr node of NU‐1000 by the same group . As an example of the second case (capture of coordinating organic ligands), Gu et al reported a superior uptake capacity of the organophosphorous pesticides, glyphosate, and glufosinate, by UiO‐67(Zr) .…”

High Uptake of ReO4− and CO2 Conversion by a Radiation‐Resistant Thorium–Nickle [Th48Ni6] Nanocage‐Based Metal–Organic Framework

“…The activated samples were immersed in 0.05 m m ReO 4 − solution for 10 h, and the corresponding samples were centrifuged and washed by water to remove the attached ReO 4 − . Inductively coupled plasma (ICP) was performed to determine the adsorption mass of ReO 4 − ; this can reach 807 mg g −1 , which are falling among the highest values known for MOF (Table and S4) . Subsequently, to explore the selectivity of 1 for capturing ReO 4 − , 5 m m Cl − , OAc − and SO 4 2− were simultaneously mixed with 0.05 m m ReO 4 − solution.…”