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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 (t1/2 = 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...

An anion inhibition study of the β-class carbonic anhydrase, AgaCA, from the malaria mosquito Anopheles gambiae is reported. A series of simple as well as complex inorganic anions, and small molecules known to interact with CAs were included in the study. Bromide, iodide, bisulphite, perchlorate, perrhenate, perruthenate, and peroxydisulphate were ineffective AgaCA inhibitors, with KIs > 200 mM. Fluoride, chloride, cyanate, thiocyanate, cyanide, bicarbonate, carbonate, nitrite, nitrate, sulphate, stannate, selenate, tellurate, diphosphate, divanadate, tetraborate, selenocyanide, and trithiocarbonate showed KIs in the range of 1.80–9.46 mM, whereas N,N-diethyldithiocarbamate was a submillimolar AgaCA inhibitor (KI of 0.65 mM). The most effective AgaCA inhibitors were sulphamide, sulphamic acid, phenylboronic acid and phenylarsonic acid, with inhibition constants in the range of 21–84 µM. The control of insect vectors responsible of the transmission of many protozoan diseases is rather difficult nowadays, and finding agents which can interfere with these processes, as the enzyme inhibitors investigated here, may arrest the spread of these diseases worldwide.

Receptors bearing hydrogen and halogen bond donors for recognition of perrhenate and pertechnetate were designed and studied. Acyclic hosts with N-H and C-H binding sites showed the best selectivity for TcO4- and ReO4- over spherical and more basic tetrahedral anions.

Rational design of anion-scavenging materials with high selectivity and stability under high acid/base extreme conditions for removing 99TcO4− is still a significant challenge. Herein, we put forward an anion exchange strategy that utilized an imidazolium-based cationic organic polymer (named ImCOP) for efficient capture of perrhenate (ReO4−), a surrogate for TcO4− with nonradioactive. ImCOP was synthesized via the quaternization reaction using tris (4-(1H-imidazol-1-yl) phenyl) amine, a tripodal flexible ligand, and 1,4-bis (bromomethyl) benzene to forming a semi-rigid structure. ImCOP exhibited high chemical stability even under 3 M HNO3 and 3 M NaOH, which was superior to those of most materials. Attributed to the charged imidazolium moieties and tertiary amine groups that produced rich adsorption sites, ImCOP can produce electrostatic interactions with ReO4−, thereby leading to a record uptake capability (1162 mg g−1) of ReO4−. Furthermore, ImCOP exhibited high selectivity for removing ReO4− in the presence of large excess of competitive anions, which was attributed to the hydrophobic surface of ImCOP. These excellent features endowed ImCOP successfully separated ReO4− from simulated Hanford waste with a high adsorption removal of 93.4%. The excellent performance suggested ImCOP would be a promising material for TcO4−/ReO4− removal, which provided a feasible pathway for designing a high-efficiency and durable material for nuclear-related environmental remediation.

For the first time the standard formation enthalpy of Bi 12.5 Nd 1.4 In 0.1 ReO 24.5 has been determined by solution calorimetry by combining the solution enthalpies of Bi 12.5 Nd 1.4 In 0.1 ReO 24.5 , 1.4NdCl 3 + 0.1InCl 3 0.1InCl 3 mixture in 2 M HCl and literature data. The lattice energy for Bi 12.5 Nd 1.4 In 0.1 ReO 24.5 has been calculated using Born-Haber cycle. The dependence of lattice energy for Bi 12.5 R 1.5 ReO 24.5 (R – rare earth element) from radius of rare earth metal was constructed. It was established that dependence was linear and had form: U lat = −129450 + 45070 r R . Linear character of experimentally obtained dependence was explained using modified variant of Kapustinskii formula obtained by us as following: U = A + Br R .

Heat capacities of sulfate, perrhenate, chloride, and iodide sodalites with the ideal formula Na8Al6Si6O24X2 (X = SO4, ReO4, Cl, I) were measured from 2 K to 300 K using a Quantum Design Physical Property Measurement System (PPMS). From the heat capacity data, the standard thermodynamic functions were determined. All four sodalites undergo a phase transition below room temperature for which thermodynamic parameters were determined. Additionally, the heat capacity of one of the constituent compounds (NaReO4) was measured.

Rhenium(VII) and molybdenum(VI) extraction with kerosene solutions of α-branched tertiary carboxylic Versatic acids derivatives containing hydrazide C(O)NHNH2 and C(O)NHNCH3)2 fragments instead of carboxyl group has been studied. Optimal extraction conditions have been determined depending on H2SO4, HCl, and extractant concentrations and composition of extracted complexes has been established. The mechanism of extraction and back extraction of perrhenate ion with ammonia solutions has been suggested.

A series of new pertechnetate, perrhenate, and perchlorate compounds of hexavalent U, Np, and Pu containing isonicotinic acid were synthesized. Their crystal structures were determined by X-ray diffractometry. In all compounds, actinide atoms are found in pentagonal bipyramidal surroundings. They are coordinated by 2 to 4 isonicotinic acid molecules which exist in zwitterionic form as a result of N atom protonation. If only 2 or 3 isonicotinic acid molecules are present in the surroundings of an actinide (An) atom, TcO4– or ReO4– anions act as monodentate ligands. Otherwise, XO4– play the role of outer sphere anions. Electron and IR spectra of the compounds correlate with their crystal structure.

Ammonium perrhenate (APR) is an intermediate product in rhenium extraction process, by which it is possible to produce rhenium powder. The main purpose of this research is to investigate the behaviour of APR in different atmospheres as a part of reduction process. In this research, differential thermal analysis and thermo gravimetric analysis are used to peruse the APR behaviour in nitrogen, argon and hydrogen atmospheres. Also for further validation, X-ray diffraction analysis and the scanning electron microscopy were used. The results indicate that APR behaves almost the same in the argon and nitrogen atmospheres. In these conditions, APR decomposes to rhenium oxides during thermal decomposition. However, APR in hydrogen reductive atmosphere is reduced to pure rhenium powder without any reactions. SEM images showed that hydrogen reduced APR had a spherical morphology, but on the other hand the directly reduced rhenium powder in hydrogen atmosphere showed flake morphology.

A static-batch technique was used to demonstrate the adsorption behavior of Re (VII) and Mo ions onto Dowex 21K at equilibrium in single and binary component systems. The single equilibrium adsorption data were modeled through a linear form of four widely used equilibrium isotherm equations. The results indicated that Freundlich and D-R models for Re, and Temkin and D–R isotherms for Mo fitted the obtained data satisfactorily. Binary adsorptions of Re and Mo ions onto Dowex 21K were also analyzed using Extended Langmuir, Modified Langmuir, Extended Freundlich and Langmuir–Freundlich models. The competitive Extended Freundlich model fitted the binary adsorption equilibrium data adequately. Studies on mutual interference effects of Mo ions on Re adsorption capacity indicated that the adsorption of perrhenate ions is always suppressed. In this perspective, the results from EDX studies confirmed the rhenium atom decrease in the simulated Re–Mo adsorption. However, under the studied conditions the affinity of the Dowex 21K for rhenium ions is marginally greater than that of molybdenum ions.

We report one of the most efficient scavenger materials, a cationic crystalline coordination polymer SBN for trapping ReO4–, a surrogate for 99TcO4–, as an anionic radioactive contaminant of great concern. The uptake capacity for ReO4– reaches 786 mg/g, a value noticeably higher than the state of art anion-exchange resins and other inorganic or hybrid anion sorbents. Once being captured, ReO4– is greatly immobilized, as almost no ReO4– can be eluted using large excess of nitrate, carbonate, and phosphate anions. The processes are featured by a complete and irreversible single-crystal to single-crystal structural transformation from SBN to the ReO4–-incorporated phase (SBR). The coordination environments of NO3– and ReO4– probed by single-crystal structures clearly unravel the underlying mechanism, where each ReO4– in SBR binds to multiple Ag+ sites forming strong Ag–O–Re bonds, and to 4,4′-bipyridine through a dense hydrogen bond network. These structural insights lead to a significant difference in solub...

Complexation of biologically active water-soluble flexible chain microassembled N-vinylpyrrolidone–N-vinylamine copolymers with ions was studied by complex chromatographic techniques (high-performance liquid chromatography and thin-layer chromatography). Constants of complex formation were evaluated (Kb = 4.6 × 105). Hydrodynamic behavior and molecular radii of the prepared metal-polymeric compounds were evaluated by molecular optics and hydrodynamic methods [viscosimetry, sedimentation diffusion analysis, dynamic light scattering, and flow birefringence (Maxwell effect)]. No significant changes in hydrodynamic properties of metal-polymeric complexes as compared with those of the pure copolymers were observed. Thus, the suggested approach seems to be promising for producing noninvasive metal-polymeric complexes for biological purposes.

We report the cloning, purification and characterization of Bps beta CA, a beta-class carbonic anhydrase (CA, EC 4.2.1.1) from the pathogenic bacterium Burkholderia pseudomallei, the etiological agent of melioidosis, and compare its activity and inhibition with those of the gamma-CA from the same organism, Bps gamma CA, recently investigated by our groups. Bps beta CA showed a significant catalytic activity for the physiologic, CO2 hydration reaction, with the following kinetic parameters, k(cat) of 1.6 x 10(5) s(-1) and k(cat)/K-m of 3.4 x 10(7) M-1 x s(-1). The inhibition of Bps beta CA with a group of anions and small molecules was also investigated. The best inhibitors were sulfamide, sulfamic acid and phenylarsonic acid, which showed K(I)s in the range of 83-92 mu M, whereas phenylboronic acid, fluoride, cyanide, azide, bisulfite, tetraborate, perrhenate, perruthenate, peroxydisulfate, perchlorate, tetrafluoroborate, fluorosulfonate and hexafluorophosphate showed K(I)s > 100 mM. Other inhibitors of this new enzyme were bicarbonate, trithiocarbonate, some complex inorganic anions and N,N-diethyldithiocarbamate, which had inhibition constants of 0.32-8.6 mM. As little is known of the life cycle and virulence of this bacterium, this type of study may bring information of interest for the development of novel strategies to fight bacterial infection and drug resistance to commonly used antibiotics. (C) 2017 Elsevier Ltd. All rights reserved.

Technetium is present as the pertechnetate anion in spent nuclear fuel solutions, and its extraction by several extractant systems is a major problem for the liquid-liquid extraction processes used to separate uranium and plutonium. To prevent technetium extraction into the organic phase, a complexing agent may be added to the aqueous nitric acid phase to selectively bind the pertechnetate anion. In the present study, liquid-liquid extraction experiments reveal that technetium distribution ratios are considerably lowered with addition of an azacryptand, which is a good receptor for pertechnetate anion recognition. This ligand is able to overcome the Hofmeister bias and selectively bind techetium in nitric acid solution. Coordination studies using infrared and Raman spectoscopies and DFT calculations show the formation of an inclusion complex with hydrogen bonds stabilizing the oxo-anion within the cavity. For the first time, the cage molecules are studied for an extraction process.

In article number 1900381, Jian‐Qiang Wang, Shuao Wang, and co‐workers develop a family of [Ln6O8]‐encapsulating polyplumbite clusters with highest adsorption capabilities toward ReO4 − among all inorganic materials, representing a new family of polyoxometalates based on Group 14 elements with application potentials in the nuclear fuel cycle and overcoming the critical drawbacks of low sorption capacity and poor selectivity for traditional inorganic anion‐exchange materials toward ReO4 −/TcO4 − sequestration.

The pertechnetate anion (99TcO4–) is a long-lived radioactive species that is soluble in aqueous solution, in contrast to sparingly soluble 99TcO2. Results are reported for photocatalytic reduction...

Pertechnetate (TcO4-) is a component of low-activity waste (LAW) fractions of legacy nuclear waste, and the adsorption removal of TcO4- from LAW effluents would greatly benefit the site remediation process. However, available adsorbent materials lack the desired combination of low cost, radiolytic stability, and high selectivity. In this study, a ZnO nanoparticle-anchored biochar composite (ZBC) was fabricated and applied to potentially separate TcO4- from radioactive effluents. The as-synthesized material exhibited γ radiation resistance and superhydrophobicity, with a strong sorption capacity of 25,916 mg/kg for perrhenate (ReO4-), which was used in this study as a surrogate for radioactive pertechnetate (TcO4-). Additionally, the selectivity for ReO4- exceeded that for the competing ions I-, NO2-, NO3-, SO42-, PO43-, Cu2+, Fe3+, Al3+, and UO22+. These unique features show that ZBC is capable of selectively removing ReO4- from Hanford LAW melter off-gas scrubber simulant effluent. This selectivity stems from the synergistic effects of both the superhydrophobic surface of the sorbent and the inherent nature of sorbates. Furthermore, density functional theory (DFT) calculations indicated that ReO4- can form stable complexes on both the (100) and (002) planes of ZnO, of which, the (002) complexes have greater stability. Electron transfer from ReO4- on (002) was greater than that on (100). These phenomena may be because (002) has a lower surface energy than (100). Partial density of state (PDOS) analysis further confirms that ReO4- is chemisorbed on ZBC, which agrees with the findings of the Elovich kinetic model. This work provides a feasible pathway for scale-up to produce high-efficiency and cost-effective biosorbents for the removal of radionuclides.

Rhenium is an element that exhibits a broad range of oxidation states. Synthesis paths of selected rhenium compounds in its seventh oxidation state, which are common precursors for organic reaction catalysts, were presented in this paper. Production technologies for copper perrhenate, aluminum perrhenate as well as the ammonia complex of cobalt perrhenate, are thoroughly described. An ion exchange method, based on Al or Cu metal ion sorption and subsequent elution by aqueous perrhenic acid solutions, was used to obtain perrhenates. The produced solutions were neutralized to afford the targeted aluminum perrhenate and copper perrhenate products in high purity. The developed technologies allow one to manage the wastes from the production of these perrhenates as most streams were recycled. Hexaamminecobalt(III) perrhenate was produced by a newly developed method enabling us to produce a high purity compound in a reaction of spent hexaamminecobalt(III) chloride solution with a perrhenic acid. All prepared compounds are the basis for precursor preparation in organic catalysis.

Capture of radioactive TcO4- from nuclear wastes is extremely desirable for waste disposal and environmental restoration. Here, we report the synthesis of hydrolytically stable cationic covalent organic nanosheets (iCON) for efficient uptake of ReO4-, a nonradioactive surrogate of TcO4-. The iCON combines cationic guanidine-based knots with hydroxyl anchored neutral edge units and chloride ions loosely bonded in the pores, rendering extremely fast exchange kinetics toward ReO4- with high uptake capacity of 437 mg g-1 and prominent distribution coefficient of 5.0 × 105. The removal efficiency remains stable over a pH range of 3-12 and allows selective capture of ReO4- in the presence of excessive competing anions such as NO3-, CO32-, PO43- and SO42- with good removal efficiency for ReO4- in a simulated Hanford LAW Melter Recycle Stream. Anion exchange between the ReO4- in solution and the chloride ion in iCON plays dominant role in the adsorption of ReO4-. The iCON shows promise for effective removal of radioactive 99Tc from nuclear waste.

Technology used to produce high purity anhydrous rubidium perrhenate on an industrial scale from high purity perrhenic acid and rubidium nitrate by the ion-exchange method is described in this paper. This material is dedicated to catalyst preparation, therefore, strict purity requirements have to be fulfilled. These are satisfied by combining rubidium ion sorption on an ion exchange column and the subsequent elution of the high purity perrhenic acid solution, followed by crystallization, evaporation, purification, and drying. In the current study, rubidium and rhenium contents were found to be 22.5 wt.% and 55.4 wt.%, respectively, while contaminations were as follows: &lt, 2 ppm As, &lt, 2 ppm Bi, &lt, 5 ppm Ca, &lt, 5 ppm Cu, &lt, 3 ppm Fe, &lt, 10 ppm K, &lt, 3 ppm Mg, &lt, 5 ppm Mo, &lt, 2 ppm Na, &lt, 5 ppm Pb, and &lt, 3 ppm Zn.

Perrhenate sodalite (Na8Al6Si6Re2O32) which contains the perrhenate anion (ReO4−) has been synthesised in equilibrium with Na–Fe-rich aluminosilicate melt and Re metal at 1100 °C and 500 MPa. Quenched glasses contain a homogeneous distribution of nepheline and magnetite, whereas sodalite only forms a crust on noble metal surfaces (Pt, Pt–Rh, Ag–Pd, and Re) in contact with the glass. The sodalite have been characterised by wavelength-dispersive X-ray spectroscopy and Raman spectroscopy. The experimental products contain both Re(0) and Re(VII), but other oxidation states of Re were not detected, suggesting the role of Na as a higher oxidation state stabiliser. Sodalite has potential uses for immobilising volatile Re and Tc during nuclear waste vitrification. Our study demonstrates the thermodynamic stability of perrhenate sodalite at Na-rich aluminosilicate melts at high temperature and pressure conditions.

Various types of polyoxometalates (POMs) have been synthesized since the 19th century, but their assortment has been mostly limited to Groups 5 and 6 metals. Herein, a new family of POMs composed of a carbon group element as the addenda atoms with two distinct phases, LnPbOClO4‐1 (Ln = Sm to Ho, Y) and LnPbOClO4‐2 (Ln = Er and Tm) is reported. Both structures are built from [Ln6O8] rare‐earth metal hexamers being incorporated in [Pb18O32]/[Pb12O24] polyplumbites, and unbound perchlorates as charge‐balancing anions. Impressively, YPbOClO4‐1 and ErPbOClO4‐2 exhibit exceptional uptake capacities (434.7 and 427.7 mg g−1) toward ReO4 −, a chemical surrogate for the key radioactive fission product in the nuclear fuel cycle 99TcO4 −, which are the highest values among all inorganic anion‐exchange materials reported until now. The sorption mechanism is clearly elucidated and visualized by single‐crystal‐to‐single‐crystal structural transformation from ErPbOClO4‐2 to a perrhenate‐containing complex ErPbOReO4, revealing a unique ReO4 − uptake selectivity driven by specific interaction within Pb···O‐ReO3 − bonds.

Water-stable [Co3(tib)2(H2O)12](SO4)3 (BUC-17) was hydrothermally synthesized by adding formic acid as a modulator. The as-prepared BUC-17, whose zeta potentials were positive in pH 4.0–10.0, was used as potential adsorbent to capture ReO4− ions. The corresponding kinetics behavior and equilibrium isotherm fitted well to the pseudo-second-order and Langmuir model, in which the maximum sorption capacity of BUC-17 was 401.9 mg ReO4− g−1 sorbent at 298 K. Additionally, BUC-17 demonstrated outstanding removal activity in wide range of pH (4.0 – 10.0) and high salinity. The fixed-bed column packed with BUC-17 powder could continuously eliminate ReO4− solution, which provided the possibility to accomplish potentially large-scale application. At last, the adsorption mechanism was proposed, which was the synergism of electrostatic interactions and ion exchange between SO42− and ReO4−.

Two novel ether-based perrhenate ionic liquids [C22OnIm][ReO4](n = 1,2) were synthesized and characterized. The static properties and transport properties were measured, and the extended properties were calculated and investigated in the certain temperature range. Using the six anions of [ReO4]−, [OAc]−, [DCA]−, [NTF2]−, [SCN]− and [TfO]− as the reference ions, the values of cationic parachor for [C22OnIm]+ (n = 1,2) were obtained for the first time. The predicted values of parachor, surface tension and refractive index of 7 kinds of ionic liquids were obtained by the cationic parachor values, which are correlated quite well with their matching experimental ones. The ether-functionalization of cation could decrease the viscosity of ILs, especially 2-ethoxyethyl (2O2) group.

The efficient decontamination of pertechnetate (99TcO4−) is an essential task for managing radioactive 99Tc in nuclear wastes. Perrhenate, (ReO4−), as a nonradioactive analog, exhibits almost identical physicochemical properties as 99TcO4−. Herein, a novel magnetic amine-functionalized MIL-101(Cr) (NH2-MIL-101(Cr)@Fe3O4) was prepared and used to efficiently remove ReO4− from solution for the facile magnetic separation. A series of environmental parameters were considered to investigate the adsorption performance of NH2-MIL-101(Cr)@Fe3O4. Experimental results suggested that NH2-MIL-101(Cr)@Fe3O4 has reached a satisfied adsorption capacity (~401 mg/g) and a very fast adsorption kinetics at pH 7.0. The selectivity for ReO4− was maintained even in the presence of interfering anions with relatively high concentrations. ReO4− were mainly captured by N-donor sites of the surface-decorated amine via complexation and were trapped in the cavities of modified MIL-101(Cr). NH2-MIL-101(Cr)@Fe3O4 exhibits satisfactory adsorption performance for ReO4− and can be conveniently separated from wastewaters after adsorption.

Two new layered barium perrhenate halides, BaX(ReO4) (X = Cl and Br), were prepared and their structures were refined from single-crystal and powder data, respectively. Both compounds are isostructural to the previously reported BaCl(MnO4), exhibiting a matlockite (PbFCl)-derived motif. The structure of previously reported PbBr(ReO4) was also refined, in order to obtain a complete data set; it is similar to PbCl(ReO4). The structures of Ba and Pb compounds correspond to the centro- and non-centrosymmetric versions (pseudo-polymorphs) of the same motif corresponding to the alternation of [M2X2]2+ litharge-derived slabs and double sheets of perrhenate anions. Strong relationships exist to the structures of LnX(TO4) (X = Cl, Br; T = Mo, W) which are monoclinically distorted versions of the orthorhombic permanganates and perrhenates. Crystal chemistry and further perspectives of the compounds with litharge slabs constructed of Cl, Br, and I-centered tetrahedra are discussed.

Rhenium is one of the most valuable elements found in nature, and its capture and recycle are highly desirable for resource recovery. However, the effective and efficient collection of this material from industrial waste remains quite challenging. Herein, a tetraphenylmethane-based cationic polymeric network (CPN-tpm) nanotrap is designed, synthesized, and evaluated for ReO4 - recovery. 3D building units are used to construct imidazolium salt-based polymers with positive charges, which yields a record maximum uptake capacity of 1133 mg g-1 for ReO4 - collection as well as fast kinetics ReO4 - uptake. The sorption equilibrium is reached within 20 min and a kd value of 8.5 × 105 mL g-1 is obtained. The sorption capacity of CPN-tpm remains stable over a wide range of pH values and the removal efficiency exceeds 60% for pH levels below 2. Moreover, CPN-tpm exhibits good recyclability for at least five cycles of the sorption-desorption process. This work provides a new route for constructing a kind of new high-performance polymeric material for rhenium recovery and rhenium-contained industrial wastewater treatment.

The development of fluorescence based sensor for perrhenate anion, which serves as a non-radioactive surrogate of hazardous pertechnetate anion, is an extremely rewarding task but nevertheless has remained rarely investigated in literature. Further, there are no reports in literature that propose a lifetime based sensing of perrhenate anion which provides significant advantage over pure intensity based sensor. Herein, we report an extremely simple fluorescence sensor for perrhenate anion in aqueous media, where we have used 1-pyrenemethylamine (PMA) as fluorescent probe. The fluorescence intensity of PMA is heavily quenched along with drastic reduction in the excited-state lifetime of PMA that provides an excellent opportunity for a very sensitive detection of perrhenate anion (LOD = 14 μM). Importantly, PMA also displays high selectivity towards perrhenate anion when compared with several other environmentally ubiquitous anions. The selective interaction between PMA and perrhenate has been attributed to the high basicity of ReO4− anion which facilitates a strong H-bonding interaction with amino group of the probe and the quenching interaction is attributed to the photoinduced electron transfer between excited PMA and ReO4−. Overall, an extremely simple, selective and sensitive fluorescence sensor for perrhenate anion is reported which also operates through lifetime measurement that is first of its kind.

Alpha-cyclodextrin based anion receptors functionalised with pendant arms containing halogen and hydrogen bond donor motifs display selective association of perrhenate in aqueous media at neutral pH. NMR and ITC anion binding investigations reveal the halogen bonding receptor to be the superior host.

Linear voltammetry is used to study the anodic behavior of a VR20 alloy in sodium hydroxide solutions, and the possibility of high-rate dc electrochemical dissolution of this alloy is shown. Experimental dependences of the rate of alloy dissolution and the anode current efficiency on the anode current density are determined, and the electric power consumed for alloy dissolution under optimum conditions is determined in large-scale tests. Potassium perrhenate is removed from the formed electrolyte as an intermediate product to form perrhenic acid. The main characteristics of the electrodialysis conversion of the synthesized potassium perrhenate into perrhenic acid with a concentration of 591 g/L electrolyte are determined. A technological scheme is proposed for the recovery of rhenium from the wastes of a W–Re alloy in the form of perrhenic acid.

Lanthanum perrhenate for use as a lubricating additive was prepared via the aqueous solution method in this study, and was dispersed into a pentaerythritol ester (PETE) base oil accompanied by surface active agents. The thermal stability of the complex oil with/without lanthanum perrhenate and surface active agents was evaluated by thermogravimetry. The influences of lanthanum perrhenate as a solid lubricating additive on the extreme pressure performance and friction-reducing property of the complex lubricants in a wide temperature range were investigated by four-ball tests and ball-on-disc frictional tests with a silicon nitride ball and Ni-base superalloy frictional pair. The results suggested that the added lanthanum perrhenate did not significantly affect the thermal stability and anti-oxidation properties of PETE, and improved the extreme pressure performance of the base oil. Additionally, it decreased the friction coefficient and wear scar diameter to a certain degree. The complex oil had a similar lubricating performance to the base oil below the decomposition temperature point; within the scope of 350 °C to 600 °C, the friction coefficients of oil containing the lanthanum perrhenate additive were markedly lower than that of the base oil, and this was attributed to lanthanum perrhenate's intrinsic shear susceptibility and resistance to phase transformation under high temperature conditions, enabling it to form an effective antifriction layer with native oxides of the superalloy matrix, thus reducing the friction in high-temperature environments.

For the first time the heat capacities of phase Bi12.5Nd1.4In0.1ReO24.5 have been measured in the temperature range of 175–550 K. Differential scanning calorimetry has been used for measurements. The temperature dependence of heat capacity is well described by a polynomial Cop,m (T) = 542.62 + 1.5107 T – 1.0402 · 10−3 T2 – 2.7875 · 106/T2. On the basis of smoothed heat capacities the enthalpy and entropy increments were calculated (T = 175–550 K).

Technetium (Tc) retention during Hanford waste vitrification can be increased if the volatility can be controlled. Incorporating Tc into a thermally stable mineral phase, such as sodalite, is one way to achieve increased retention. Here, rhenium (Re)-bearing sodalite was tested as a vehicle to transport perrhenate (ReO4−), a nonradioactive surrogate for pertechnetate (TcO4−), into high-level (HLW) and low-activity waste (LAW) glass simulants. After melting HLW and LAW simulant feeds, the retention of Re in the glass was measured and compared with the Re retention in glass prepared from a feed containing Re2O7. Phase analysis of sodalite in both these glasses across a profile of temperatures describes the durability of Re-sodalite during the feed-to-glass transition. The use of Re sodalite improved the Re retention by 21% for HLW glass and 85% for LAW glass, demonstrating the potential improvement in Tc-retention if TcO4− were to be encapsulated in a Tc-sodalite prior to vitrification.

The processes of electrodeposition of rhenium and its alloys with nickel from aqueous solutions are considered. The results of theoretical and experimental studies of the process of perrhenate ion reduction are analyzed: the data on the possible mechanisms of the cathodic process, participation of atomic hydrogen in it, potentials of transition of rhenium to different oxidation degrees. Codeposition of rhenium and nickel is discussed. The effect of complexation on the current efficiency of rhenium deposition is considered. Information of the sources of data discussed in this paper is provided.