Electrochemical, complexation, and electronic properties of uranyl(VI) -(V) carbonato complexes in an aqueous Na2CO3 solution have been investigated to define the appropriate conditions for preparing pure uranyl(V) samples understand difference coordination character between UO22+ UO2+. Cyclic voltammetry using three different working electrodes platinum, gold, glassy carbon has suggested that electrochemical reaction carbonate species proceeds quasi-reversibly. Electrolysis performed...

Electrochemical and complexation properties of neptunium (Np) are investigated in aqueous perchlorate nitrate solutions by means cyclic voltammetry, bulk electrolysis, UV−visible absorption, Np LIII-edge X-ray absorption spectroscopies. The redox reactions NpIII/NpIV NpV/NpVI couples reversible or quasi-reversible, while the electrochemical reaction between NpIII/IV NpV/VI is irreversible because they undergo structural rearrangement from spherical coordinating ions (Np3+ Np4+) to...

Cerium(III) and cerium(IV) both form formate complexes. However, their species in aqueous solution the solid-state structures are surprisingly different. The solutions were investigated with Ce K-edge EXAFS spectroscopy. Ce(III) shows only mononuclear complexes, which is agreement predicted of Ce(HCOO)(2+) Ce(HCOO)2(+). In contrast, Ce(IV) forms a stable hexanuclear complex [Ce6(μ3-O)4(μ3-OH)4(HCOO)x(NO3)y](12-x-y). structural differences reflect different influence hydrolysis, weak for...

In order to elucidate the uranium solution chemistry at high HNO(3) concentrations typically employed for reprocessing of spent nuclear fuels, speciation and complex structures U(IV) U(VI) are studied in aqueous solutions, as well HClO(4) by means UV-visible-near-infrared X-ray absorption spectroscopies density functional theory calculations. 1.0 M HClO(4), exists a spherical cation U(4+), which is surrounded 9-10 water molecules primary coordination sphere, while it forms colloidal hydrous...

Successful synthesis of the first transuranium metal-organic frameworks (TRU-MOFs) involving tetravalent Np4+ is reported. These compounds were obtained from controlled hydrolysis in presence dicarboxylate ligands. The final structures contain [Np6O4(OH)4(H2O)6]12+ unit, which never crystallized before with neptunium, associated ditopic

We studied the structure and stoichiometry of aqueous uranylVI hydroxo dimers trimers by spectroscopic (EXAFS, FTIR, UV-vis) quantum chemical (DFT) methods. FTIR UV-vis spectroscopy were used for speciation uranyl complexes in solution. DFT calculations show that (UO2)2(OH)22+ has two bridging groups with a U-U distance 3.875 A. This result is good agreement EXAFS, where 3.88 A was found. For trimer complex, species (UO2)3(O)(OH)3+ oxo center energetically favored comparison to its...

The local structure around the La(3+) ions in molten LaCl(3) and its mixtures with alkali alkaline earth chlorides has been investigated by using extended X-ray absorption fine (XAFS) molecular dynamics (MD) techniques. Such mixtures, which are of current technological interest, known to be thermodynamically nonideal, there a good deal work understand structural effects factors that contribute nonideality. New experimental methods allow observations at La K-absorption edge high temperatures...

Silver nanoparticle (AgNP)-impregnated rice husks/rice hush ash (RHs/RHA) were successfully synthesized, and their potential application as antibacterial materials in water disinfection was investigated with particular attention given to the use of both white husk (WRHA) black (BRHA) produced by combustion RHs AgNP supports. AgNPs, diameter ∼20 nm, anchored tightly onto RHA, emplacement AgNPs on these supports increasing activity through diminution extent aggregation. Ag K-edge XANES...

Primary aquo species of tetravalent cerium (Ce(IV)) in perchloric acid has been identified as a single oxo-bridging dinuclear complex, not mononuclear one, by extended X-ray absorption fine structure (EXAFS) spectroscopy combined with density functional theory (DFT) calculations.

The coordination and redox behavior of Np(IV), Np(V), Np(VI) sulfate in aqueous solution were investigated by Np L(3)-edge extended X-ray absorption fine structure (EXAFS) spectroscopy, cyclic voltammetry, density functional theory (DFT) calculations. mode, that is, monodentate versus bidentate, was determined using neptunium-sulfur distances R(Np-S) numbers N(S) obtained EXAFS spectroscopy. is coordinated the bidentate (R(Np-S) = 3.12 +/- 0.02 A) 3.61 modes at a low concentration...

The limiting U(IV) carbonate species in aqueous solution was investigated by comparing its structure parameters with those of the complex preserved a crystal structure. prevails 0.05 M and 1 NaHCO3 at pH 8.3. Single crystals Na6[U(CO3)5]·12H2O were obtained directly from this mother solution. identified as monomeric [U(CO3)5]6− anionic complex. interatomic distances around coordination polyhedron show average U–O = 2.461(8) Å, U–C 2.912(4) Å U–Odist 4.164(6) Å. U L3–edge EXAFS spectra...

A strategy for the formation of uranium(<sc>iv</sc>) clusters consists water release from esterification reaction to generate {U₃₈} species.

The poly-oxo clusters of neptunium, {Np₃₈}, fill the gap in largest cluster series tetravalent actinides.

The electrochemical behavior and complex structure of Np carbonato complexes, which are major concern for the geological disposal radioactive wastes, have been investigated in aqueous Na2CO3 Na2CO3/NaOH solutions at different oxidation states by using cyclic voltammetry, X-ray absorption spectroscopy, density functional theory calculations. end-member complexes penta- hexavalent 1.5 M with pH = 11.7 determined as a transdioxo neptunyl tricarbonato complex, [NpO2(CO3)3]n− (n 5 NpV, 4 NpVI)....

Four metal-organic coordination polymers bearing uranium or neptunium have been hydrothermally synthesized from a tetravalent actinide chloride (AnCl4) and phthalic (1,2-H2bdc) mellitic (H6mel) acid in aqueous media at 130 °C. With the phthalate ligand, two analogous assemblies ([AnO(H2O)(1,2-bdc)]2·H2O; An = U4+ (1) Np4+ (2)) isolated, which square-antiprismatic polyhedra of AnO8 are linked to each other via μ3-oxo groups with an edge-sharing mode materialize infinite zigzag ribbons. The...

Despite the rapid developments in recent nanocrystal research and their expanding applications, evolution mechanism of nanocrystals remains veiled for most part due to lack appropriate analytical techniques. Here we demonstrate one promising multi-spectroscopic approach situ investigation evolution. That is, formation nanocrystalline cerium dioxide (NC-CeO2) has been probed by dynamic light scattering (DLS), X-ray absorption spectroscopy (XAS) high-energy (HEXS). The obtained results...

UraniumIV sulfate in an aqueous solution and the solid state has been investigated with extended X-ray absorption fine structure (EXAFS) diffraction (XRD). The coordination polyhedron comprises monodentate sulfate, bidentate water molecules. modes of have determined from U-S distances EXAFS. distance 3.67 +/- 0.02 A indicates 3.08 coordination. obtained sulfur numbers a [SO42-]/[U4+] ratio 40 suggest species compositions [U(SO4,bid)2(SO4,mon)2 x nH2O]4- [U(SO4,bid)3 (SO4,mon)2 mH2O]6-....

High quality epitaxial SrCoO x (oxygen deficient 3 ) thin films were grown on (110) DyScO3 substrates by pulsed laser deposition.The disappearance of half order peaks in X‐ray diffraction as well the XAS at O K‐edge indicates an oxygen content ≈ 2.8 films. Magnetization measurements reveal that specific substrate strain suppresses ferromagnetism found corresponding bulk material and emergence antiferromagnetic‐type spin correlation predicted theoretical calculations. Our work demonstrates...

During the 1960s, radioactive waste containing small amounts of plutonium (Pu) and americium (Am) was disposed in shallow trenches at Little Forest Burial Ground (LFBG), located near southern suburbs Sydney, Australia. Because periodic saturation overflowing former disposal trenches, Pu Am have been transferred from buried wastes into surrounding surface soils. The presence readily detected trench waters provides a unique opportunity to study their aqueous speciation under environmentally...

In the multibarrier concept for deep geological disposal of high-level radioactive waste (HLW), bentonite is proposed as a potential barrier and buffer material sealing space between steel canister containing HLW surrounding host rock. order to broaden spectra appropriate bentonites, we investigated metabolic activity diversity naturally occurring microorganisms well their time-dependent evolution within industrial B25 Bavarian under repository-relevant conditions. We conducted anaerobic...

Batch sorption experiments, potentiometric and spectroscopic titration investigations revealed a fast strong interaction of Eu(<sc>iii</sc>) Cm(<sc>iii</sc>) with the digestive enzyme α-amylase.