Bal Govind Vats

A systematic multiparametric investigation was performed to elucidate the synthesis−structure−property relationship of a UiO-66-type thorium-based 2-aminoterephthalate metal−organic framework (Th-ABDC) for iodine capture. The effects of synthesis temperature (100, 125, 150, and 175 °C), reaction duration (16 h, 24 h, and 48 h), metal-to-linker (M/L) ratio (1:1, 1:1.5, and 1:2), and modulator type (acetic acid, 2-fluorobenzoic acid, 4-aminobenzoic acid, and trifluoroacetic acid) were systematically investigated. Notably, 4-aminobenzoic acid (ABA) was employed as a modulator to mitigate the loss of amino functionality resulting from modulator incorporation into the framework during synthesis. Preserving the amino groups is expected to enhance iodine uptake through favorable host−guest interactions. The synthesized MOFs were comprehensively characterized using powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), 1H nuclear magnetic resonance (1H NMR) spectroscopy, field-emission scanning electron microscopy (FESEM), and N2 adsorption−desorption isotherms to establish correlations between synthesis parameters, framework composition, morphology, porosity, structural defects, and iodine adsorption performance. The optimized MOF synthesized at lower temperatures, shorter reaction durations, an M/L ratio of 1:1, and using ABA as the modulator exhibited smaller particles with a bimodal size distribution, fewer linker defects, and a higher specific surface area, resulting in superior gas-phase iodine adsorption capacity. Furthermore, MOF−polyethersulfone (MOF−PES) composite beads were fabricated and evaluated for iodine removal from cyclohexane solution. Dynamic iodine adsorption studies demonstrated a maximum iodine uptake of approximately 1.5 g g−1 for the optimized MOF−PES beads synthesized at 150 °C using ABA as the modulator. The MOF−PES composite also exhibited excellent acid resistance, retaining its UiO-66 crystal structure after prolonged exposure (100 h) to nitric acid while maintaining its iodine adsorption capability. The findings provide valuable design principles for the rational development of robust, high-performance thorium MOFs for radioactive iodine capture and related environmental remediation applications.

Thorium‐based UiO‐66/67 metal‐organic frameworks (MOFs) are studied among the most promising radioactive iodine traps to achieve sustainable clean nuclear energy. Here, seven MOFs, namely, Th‐BDC, Th‐1,4‐NDC, Th‐ADC, Th‐ABDC, Th‐2,6‐NDC, Th‐BiPhDC, and Th‐BiPyDC (where BDC= benzene‐1,4‐dicarboxylic acid; 1,4‐NDC = naphthalene‐1,4‐dicarboxylic acid; ADC = anthracene‐9,10‐dicarboxylic acid; ABDC = 2‐aminobenzene‐1,4‐dicarboxylic acid; BiPhDC = 1,1′‐biphenyl‐4,4′‐dicarboxylic acid; BiPyDC = 2,2′‐bipyridyl‐5,5′‐dicarboxylic acid), are synthesized and characterized employing powder X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy, surface area measurement, Fourier‐transform infrared, and Raman spectroscopy. MOFs having large linker lengths, namely, Th‐2,6‐NDC, Th‐BiPhDC, and Th‐BiPyDC, are collapsed during solvent drying. I₂ vapor adsorption studies are carried out, and the I₂@MOFs are characterized. MOFs with similar linker lengths but different numbers of aromatic rings (Th‐BDC, Th‐1,4‐NDC, Th‐ADC) have similar SSA (specific surface area) normalized I₂ adsorption capacities (≈0.9 g/g). Among the UiO‐66‐type MOFs, ThBDC stands out to have highest I₂ adsorption capacity of ≈1.7 g/g due to the presence of an electron‐donating group on the aromatic ring. This study provides the rationale to design better MOFs for I₂ adsorption and gives insight that the electron density modulated by the electron‐donating group on the linker is more significant than increasing the number of aromatic rings in UiO‐66 family.

The structure and stability of charge-coupled lanthanide-substituted Ca-10(PO4)(6)F-2 as a potential fluoride-bearing nuclear waste form for the back-end fuel cycle of Gen-IV molten salt reactor have been studied in detail. Here, calcium fluorapatite (CaFAp) as a model structure was taken for incorporation of trivalent lanthanides (Lns, La-Lu except Pm) in a charge-coupled fashion, i.e., 2Ca(2+) = Na+ + Ln(3+). In these fluorapatite phases, Na+ is substituted exclusively at nine coordinated sites, Ca1, while Ln(3+) is preferentially substituted at seven coordinated sites, Ca2. These compositions are further characterized for the local structure by Fourier transform infrared (FTIR) and Raman spectroscopy. Thermal expansion was measured by high-temperature X-ray diffraction (XRD) and the instantaneous thermal expansion coefficient correlates well with the unsubstituted CaFAp. The heat capacities of these solids were measured by differential scanning calorimetry and drop calorimetry, whereas enthalpies of formation were obtained by high-temperature oxide melt solution calorimetry. The thermodynamic analysis demonstrated that lanthanides having ionic radii closure to Ca2+ (Sm3+ and Gd3+) imparted higher thermodynamic stability to the substituted CaFAp as compared to that of other Ln(3+). According to structural and thermodynamic investigations, entropy-stabilized fluorapatite waste from NaPr0.125Nd0.125Sm0.125Eu0.125Gd0.125Tb0.125Dy0.125Ho0.125Ca8(PO4)(6)F-2 (WF-Ln) was successfully synthesized for the first time. Furthermore, electron beam irradiation studies probed by XRD, FTIR, Raman, and X-ray absorption (XAS) spectroscopy implied the radiation resistance nature of this substituted CaFAps up to 20 MGy.

Two copper complexes, CuX(dmpymSH)(PPh ₃ ) ₂ (where X = Cl or I), were applied as efficient single source precursors for phase selective isolation of Cu ₉ S ₅ (digenite) and Cu ₃₁ S ₁₆ (djurleite) nanomaterials in pure form.

Hydrophobic Deep Eutectic Solvents (DESs) have been attracting attention for metal ion extraction in solvent extraction process due to their favorable properties. A Trioctyl phosphine oxide (TOPO) and Thenoyl trifluoroacetone (HTTA) based hydrophobic DES was synthesized and characterized by FTIR and NMR spectroscopy. Actinide ions ( UO₂²⁺, Pu⁴⁺ and Am³⁺) and Eu³⁺ ion extraction was carried out using the DES which shows that it extracts these metal ions from aqueous nitric acid medium depending upon the molarity of nitric acid. At higher molarity of nitric acid (>5 M) the extraction becomes insignificant only for trivalent metal ions and open up the possibility to selectively strip trivalent metal ions from tetravalent and hexavalent ions. This DES was also used for dissolution of uranium oxide (UO₃). The dissolution kinetics was studied and it was shown that oxide was dissolved within an hour at 80 °C. The maximum solubility of UO₃ in DES was measured and found to be 130±5 mg/mL which is one of the highest reported solubility of UO₃ in ILs and DES. The species of uranium which is formed in situ in DES was ascertained to be UO₂(TTA)₂.TOPO after dissolution of UO₃ as supported by FTIR and NMR (¹H and ³¹P) investigations.

Copper and copper oxide nanostructures are ubiquitous in materials science owing to their high potential in energy and environment applications. This article describes the utility of a 2D Cu(II) coordination polymer (2D-CuPDC) derived from 2,5-pyridinedicarboxylic acid linker, as a precursor for selective isolation of Cu and CuO nanostructures. The structure of the coordination polymer has been elucidated from single crystal XRD. The Cu center in 2D-CuPDC is in a distorted square pyramidal geometry with the polymeric unit propagating along the ac-plane when viewed along the a-axis. The thermogravimetric analysis of 2D-CuPDC indicates that it can be an efficient molecular precursor for copper oxide nanoparticles. The solvent assisted and solvent free breakdown of the 2D-CuPDC network revealed the formation of Cu nano-flowers and porous CuO nanostructures, respectively. The crystal structure, phase purity, morphology, elemental composition and band gap of these nanostructures were evaluated from pXRD, electron microscopy, EDS and DRS-UV, respectively. The band gap of these nanostructures lies in the range suitable for photocatalytic applications. This coordination polymer driven synthesis of Cu and CuO nanostructures can be expanded for other technologically important metal and metal oxide nanostructures.

This article presents the synthesis of a single-phase red emitting Y ₂ Ge ₂ O ₇ :Eu ³⁺ soft-UV excitable phosphor with up to 10% Eu ³⁺ content. Experimental and theoretical exploration has established its relative potential with respect to the commercial Y ₂ O ₃ :Eu ³⁺ phosphor.