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Srivastava A, Ali SM, Dumpala RMR, Kumar S, Kumar P, Rawat N, Mohapatra PK. Unusual redox stability of pentavalent uranium with hetero-bifunctional phosphonocarboxylate: insight into aqueous speciation. Dalton Trans 2024; 53:7321-7339. [PMID: 38591248 DOI: 10.1039/d4dt00173g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2024]
Abstract
The +5 state is an unusual oxidation state of uranium due to its instability in the aqueous phase. As a result, gaining information about its aqueous speciation is extremely difficult. The present work is an attempt in that direction and it provides insight into the existence of a new pentavalent species in the presence of hetero-bifunctional phosphonocarboxylate (PC) chelators, other than the carbonate ion, in the aqueous medium. The aqueous chemistry of pentavalent uranium species with three environmentally relevant PCs was probed using electrochemical and DFT methods to understand the redox energy and kinetics of conversion of the U(VI)/U(V) couple, stability, structure, stoichiometry, binding modes, etc. Interestingly, pentavalent uranium complexes with PCs are quite persistent over a wide range of pH starting from acidic to alkaline conditions. The PC chelators block the cation-cation interaction (CCI) of U(V) through strong hetero-bidentate chelation and intermolecular hydrogen bonding (IMHB) interactions which stabilize the pentavalent metal ion against disproportionation. For uranyl species in the presence of PCs, acting as chelators, CV plots were obtained at varying pH values from 2 to 8. The obtained results indicate an irreversible single redox peak involving U(VI) to U(V) conversion and association of a coupled chemical reaction with the electron transfer step. ESI-MS studies were performed to understand the speciation effect on the U(VI)/U(V) redox couple with varying pH. Speciation modelling of U(V) with the PC ligands was carried out, which indicated that the U(V) is redox stable in nearly 47% of the pH region in the presence of the PCs as compared to the carboxylate-based chelators. The free energy and reduction potential of the U(V) complexes and the reduction free energy and disproportionation free energy for the U(VI)/U(V) couple were determined by DFT computations in the presence of the PCs. In situ spectroelectrochemical spectra were recorded to provide evidence for the existence of U(V) species with PCs in the aqueous medium and to acquire its absorption spectra. The present study is highly significant for understanding the coordination chemistry of pentavalent uranium species, accurate modelling of uranium, and isolation of U(V).
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Affiliation(s)
- Ashutosh Srivastava
- Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai, India-400085.
| | - Sk Musharaf Ali
- Chemical Engineering Division, Bhabha Atomic Research Centre, Mumbai, India-400085
| | | | - Sumit Kumar
- Radioanalytical Chemistry Division, Bhabha Atomic Research Centre, Mumbai, India-400085
| | - Pranaw Kumar
- Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai, India-400085
| | - Neetika Rawat
- Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai, India-400085.
| | - P K Mohapatra
- Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai, India-400085.
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Knapp JG, Livshits MY, Gilhula JC, Hanna SL, Piedmonte ID, Rice NT, Wang X, Stein BW, Kozimor SA, Farha OK. Influence of Linker Identity on the Photochemistry of Uranyl-Organic Frameworks. ACS APPLIED MATERIALS & INTERFACES 2023; 15:43667-43677. [PMID: 37672765 DOI: 10.1021/acsami.3c06897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
Abstract
While uranyl-based metal-organic frameworks (MOFs) boast impressive photocatalytic abilities, significant questions remain regarding their excitation pathways and methods to fine-tune their performance due to the lack of information regarding heterogeneous uranyl catalysis. Herein, we investigated how linker identity and photoexcitation impact uranyl photocatalysis when the uranyl coordination environment remains constant. Toward this end, we prepared three uranyl-based MOFs (NU-1301, NU-1307, and ZnTCPP-U2) and then examined the structural and photochemical properties of each through X-ray diffraction, X-ray absorption, and photoluminescence. We then correlated our observations to the photocatalytic performance for fluorination of cyclooctane. The excitation profile from NU-1301 and NU-1307 exhibited spin-forbidden linker transitions and uranyl vibronic progressions, with uranyl excitation and emission being most dominant in NU-1301. Consequently, NU-1301 was a more active photocatalyst than NU-1307. In contrast, the excitation profile from ZnTCPP-U2 contained transitions associated with the porphyrin linker exclusively. Photocatalytic activity from ZnTCPP-U2 significantly underperformed in comparison to that of the other two MOFs. These data suggest that linkers' photophysical properties can be used to predict the photocatalytic behavior of uranyl-containing MOFs.
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Affiliation(s)
- Julia G Knapp
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Maksim Y Livshits
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - J Connor Gilhula
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Sylvia L Hanna
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Ida D Piedmonte
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Natalie T Rice
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Xingjie Wang
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Benjamin W Stein
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Stosh A Kozimor
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Omar K Farha
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Chemical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
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Şimşek S, Derin Y, Kaya S, Şenol ZM, Katin KP, Özer A, Tutar A. High-Performance Material for the Effective Removal of Uranyl Ion from Solution: Computationally Supported Experimental Studies. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:10098-10113. [PMID: 35946525 PMCID: PMC9404547 DOI: 10.1021/acs.langmuir.2c00978] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 07/29/2022] [Indexed: 05/19/2023]
Abstract
Adsorption is a widely used method for pollution removal and for the recovery of valuable species. In recent years, the use of metal-organic compounds among the adsorbents used in adsorption studies has increased. In this study, the performance of the water-insoluble Fe complex as a metal organic framework (MOF-Fe-Ta) of water-soluble tannic acid, which is not used as an adsorbent in uranium recovery and removal, was investigated. For the characterization of the new synthesized material, Fourier transform infrared, scanning electron microscopy, and X-ray diffraction analyses were performed. The changes in the adsorption process based on various parameters were investigated and discussed. The point of zero charges value of the adsorbent was found as 5.52. It was noticed that the adsorption increases as the pH increases. Analyzing the effect of concentration on adsorption, we determined which model explained the adsorption better. The monolayer capacity of the adsorbent determined in light of the Langmuir model was reported as 0.347 mol kg-1. The Freundlich constant, namely the β value obtained in the Freundlich model, which is a measure of surface heterogeneity, was found to be 0.434, and the EDR value, which was found from the Dubinin-Raduskevich model and accepted as a measure of adsorption energy, was 10.3 kJ mol-1. The adsorption was kinetically explained by the pseudo-second-order model and the adsorption rate constant was reported as 0.15 mol-1 kg min-1. The effect of temperature on adsorption was studied; it was emphasized that adsorption was energy consuming, that is, endothermic and ΔH was found as 7.56 kJ mol-1. The entropy of adsorption was positive as 69.3 J mol-1 K-1. As expected, the Gibbs energy of adsorption was negative (-13.1 kJ mol-1 at 25 °C), so adsorption was considered as a spontaneous process. Additionally, the power and mechanism of the interaction between studied adsorbent and adsorbate are explained through density functional theory computations. Computationally obtained data supported the experimental studies.
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Affiliation(s)
- Selçuk Şimşek
- Faculty
of Science, Department of Chemistry, Sivas
Cumhuriyet University, 58140 Sivas, Turkey
- Selçuk
Şimşek.
| | - Yavuz Derin
- Department
of Chemistry, Sakarya University, 54050 Sakarya, Turkey
| | - Savaş Kaya
- Health
Services Vocational School, Department of Pharmacy, Sivas Cumhuriyet University, 58140 Sivas, Turkey
- Savaş Kaya.
| | - Zeynep Mine Şenol
- Zara
Vocational School, Department of Food Technology, Sivas Cumhuriyet University, 58140 Sivas, Turkey
| | - Konstantin P. Katin
- Institute
of Nanoengineering in Electronics, Spintronics and Photonics, National Research Nuclear University “MEPhI”, Kashirskoe Shosse 31, Moscow 115409, Russia
| | - Ali Özer
- Engineering
Faculty, Metallurgical and Materials Engineering Department, Sivas Cumhuriyet University, 58140 Sivas, Turkey
| | - Ahmet Tutar
- Department
of Chemistry, Sakarya University, 54050 Sakarya, Turkey
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