Molybdenum In Solution Research Articles

Research of Potential Production 94mTc in Medical Cyclotron

To expand the spectrum of used radiopharmaceuticals, it is proposed to obtain a positron-emitting isotope of technetium 94mTc. The intention of this work is to research the possibility of producing various technetium isotopes on a medical cyclotron. For this purpose, we carried out a series of irradiations of an aqueous solution of molybdenum of natural isotopic composition with protons of 11 MeV energy. After technetium isolation, results were analyzed on a γ-spectrometer. 511 keV gamma-ray line was obtained.

FORMATION AND DECOMPOSITION OF ANOMALOUS SUPERSATURATED MOLYBDENUM SOLUTIONS IN COPPER-BASED CONDENSATES


 Cu-Mo condensates in the concentration range of the latter from 0.3 to 1.5 at.%, obtained by simultaneous evaporation in vacuum with subsequent condensation of the resulting vapor mixture on a non-orienting substrate (PVD method), were studied. The components of this system do not form chemical compounds under equilibrium conditions and are mutually insoluble in liquid and solid states. The structure of Cu-Mo condensates was studied by transmission electron microscopy and X-ray diffractometry both in the derivative state and after a series of isothermal anneals in the temperature range from 300 to 900°C. It was found that small concentrations of molybdenum lead to significant dispersion of the matrix metal. Molybdenum tends to form segregations at the boundaries of copper grains and form a strong coherent bond with the matrix metal, which persists even after isothermal annealing. The conditions for the formation of an anomalous supersaturated solid solution of molybdenum in the copper matrix, as well as the conditions for its decomposition, have been revealed. An assumption is made about the mechanism of formation of such a solution during condensation from the vapor phase, which consists in the kinetic capture of molybdenum atoms by the crystallization front during condensation from the vapor phase. It was found that the decomposition of the supersaturated solid solution begins when heated to 0.5 of the melting point of copper and is accompanied by a dispersion solidification process. During the experiment, it was first recorded that the dispersion solidification process can have a two-stage character. The first peak is observed in the region of 30 minutes of annealing, and the second peak is observed after about 2 hours of isothermal annealing. The height of the dispersion hardening peaks increases with increasing molybdenum concentration. It is suggested that the appearance of the second peak of dispersion hardening is associated with the peculiarities of the interaction between copper grains and molybdenum segregations at the grain boundaries. It is shown that the structure after solution decomposition is typically composite. The advantage of this material over conventional dispersively hardening alloys is the fact that in these pseudo-alloys there is no reverse solution of hardening particles at an increase in temperature.

A novel method for preparing tungsten and molybdenum peroxy complex solution and its application to tungsten - molybdenum separation

Aiming at the shortcomings of existing separation technology of tungsten (W) and molybdenum (Mo) by hydrogen peroxide (H2O2) complexation, the chemical behaviors of W(VI) and Mo(VI) in aqueous solutions were studied and a new method for preparing W(VI)-Mo(VI)-H2O2 solution was proposed. By using trialkyl phosphine oxide-tributyl phosphate (TRPO-TBP) as a mixed extractant system, the applications of this new method on separation of W and Mo were conducted, including the effect on third phase formation and elimination, satisfactory removal of Mo, and separation efficiency of Mo and W. The results show that the formation and depolymerization of isopoly and heteropoly compounds of W and Mo have an important influence on their separation. The core of the new method lies in the control of pH value when W and Mo begin to complex with H2O2. The formation of metatungstate and heteropoly compounds with high Mo/W atomic ratio could be avoided by adding H2O2 into the mixed solution of tungsten and molybdenum in a high pH range of 5.3–6.5 for complexation. Based on this principle, this method could not only avoid the third phase formation at the source but also effectively improve the satisfactory removal of molybdenum. As the complexation pH value increased from 3.51 to 5.51, after six-stage countercurrent extraction of feed solution containing about 127.8 g/L WO3 and 16.10 g/L Mo, the mass ratio of Mo/WO3 in raffinate decreased from 5.94 × 10−4 to 2.71 × 10−5 and the molybdenum content decreased from 77.50 mg/L to 3.54 mg/L. This study provides a relevant theoretical foundation and feasible improvement for the satisfactory separation of W and Mo from peroxy complex solution system, and is expected to facilitate the industrialization of this technology.

INFLUENCE OF TUNGSTEN AND MOLYBDENUM ON Н2О2 ACCUMULATION IN N.BENTHAMIANA PLANT

The problem of soil pollution with heavy metals is one of the main factors hindering the development of agriculture in Kazakhstan. Soil pollution with heavy metals, especially tungsten, leads to a deterioration in plant growth and development, the formation of active oxygen radicals, and oxidative stress. In plants, tungsten (W) acts as an inhibitor of molybdoenzymes, replacing molybdenum (Mo) in the Mo-cofactor structure. At the same time, Mo itself at high concentrations also negatively affects plant cells. When exposed to tungsten and molybdenum, reactive oxygen species (ROS) accumulate excessively in the plant. When the test plant N. benthamiana is exposed to molybdenum, the accumulation of Н2О2 is sharply reduced compared to the control plant, and in plants treated with a solution of tungsten, the accumulation of Н2О2 is increased by 2 times. The accumulation of Н2О2 in plants treated with a combined solution of molybdenum and tungsten was higher compared to the control plant. An interesting result is an increase in the accumulation of Н2О2 by 3.5 times when exposed to tungsten compared to molybdenum.

Structural Features of Glands in the Sphincter Zones of the Large Intestine of an Adult

The aim is to study macro- and microscopic structure, as well as the cellular composition of the glands of the sphincter zones of large intestine of adults of different age groups.Material and methods. On autopsy material obtained from 30 people, without signs of pathology of the digestive tract of three age groups: 20–29 years, 50–59 years, 90–99 years, the structure of the glandular apparatus of the sphincter zones was studied. The areas of the Gerlach flap, Girsch sphincters, Payr–Strauss, Bally, O'bern–Pirogov–Moutier were considered. Quantitative morphometry was performed on histological preparations stained with methylene blue, followed by fixation in a saturated solution of ammonium molybdenum (picric acid), hematoxylin-eosin, picrofuchsin according to Van Gieson. Methods of parametric statistics based on the Statistica 6.0 program were used for statistical data processing.Results. The analysis of the number, size and cellular composition of the glands of the sphincter zones of the large intestine revealed an increase in both the number of glands and their size in all age groups compared to the proximally adjacent areas of the intestine, on average by 1.3–1.5 times. In a similar range, individual indicators of the number of epithelial cells in the glands of the sphincter zones of the colon increased. At the same time, the cellular composition of the glands of the sphincter zones and adjacent areas of the intestinal wall was similar to neighboring areas, with predominant goblet-shaped epithelial cells (52.9–54.2% of cells on the longitudinal section of the gland) and the presence of absorption cells (29.9–31.2%), undifferentiated – 11.9–13.2% and argyrophilic endocrinocytes – 1.4–5.3%.Conclusion. Against the background of narrowing of the lumen of the large intestine in the area of the sphincters and changes in the nature of the mucous membrane, there is an increase in the size and density of the localization of glands in all age groups. This confirms the thesis about the formation of a protective barrier that provides a local adaptive potential of this area of the intestinal wall, against the background of increased mechanical effects of intestinal masses.

Extracting Technetium from Neutral Molybdenum Solution with Activated Carbon Filber

Extracting Technetium from Neutral Molybdenum Solution with Activated Carbon Filber

The Triple Salt 2(C7H9N4O2)[MoOCl4(H2O)] ⋅ 2(C7H9N4O2)Cl ⋅ (H17O8)Cl Containing a C2‐symmetrical Unbranched H+(H2O)8Zundel type Species in a Framework Composed of Theophyllinium, Aquatetrachloridooxidomolybdate and Chloride Ions

AbstractFrom a concentrated hydrochloric acid solution of molybdenum‐(V) chloride and theophylline octaaquahydrogen(1+) tetrakis(theophyllinium) bis[aquatetrachloridooxidomolybdate(1−)] tri‐chloride, C7H9N4O2)4(H17O8)[MoOCl4(H2O)]2Cl3, (1) was obtained. The light emerald green inorganic‐organic hybrid material can be rationalized as a triple salt according to the formula 2(C7H9N4O2)[MoOCl4(H2O)] ⋅ 2(C7H9N4O2)Cl ⋅ (H17O8)Cl. The ions involved are connected by charge‐supported hydrogen bonds to form a 3D framework. The unique H17O8+ moiety features a chain of eight hydrogen bonded water molecules, with the excess proton defining a H5O2+ Zundel‐ion (O⋅⋅⋅O distance 240.3(6) pm) in the middle of the chain, and is placed with crystallographic site symmetry 2. Although engaged in strong O−H⋅⋅⋅O bonding to the neighboring water molecules in the chain (O⋅⋅⋅O distance 262.9(4) pm) and in hydrogen bonding to a carbonyl group of a theophyllinium ion, both the conformation of the H5O2+ unit and the geometry of the very strong central O−H−O bond fit to the C2‐symmetrical global minimum structure of an isolated H5O2+ species. The outer water molecules of the H17O8+ moiety are further engaged in N−H⋅⋅⋅O, O−H⋅⋅⋅Cl and O−H⋅⋅⋅O=C bonds.

Highly efficient and selective capture of TcO4− or ReO4− by imidazolium-based ionic liquid polymers

• DVB-2C 8 VEIMBr has a great adsorption capacity of 313.28 mg g −1 for TcO 4 − . • It can remove 93% of TcO 4 − from the simulated Hanford LAW scrubber solution. • It shows excellent selectivity in the 6000 times SO 4 2− mixture solution. • It displays super stability being immersed in 3 M HCl or 2 M NaOH for 8 months. • DVB-2C 8 VEIMBr unfolds prominent regeneration ability after ten consecutive cycles. 99 Technetium ( 99 Tc) is one of the most dangerous radioactive isotopes in the legacy nuclear waste, and harmful to the environment and human health. Effectively removing it remains a long-term challenge. Herein a resin-like imidazolium-based ionic liquid polymer (DVB-2C 8 VEIMBr) was prepared for selective adsorption of TcO 4 − (ReO 4 − as an alternative for laboratory operation). It is manifested that DVB-2C 8 VEIMBr integrates high adsorption capacity (313.28 mg·g −1 ) and selectivity (90.68% in 6000 times excess of SO 4 2− ions). A real-scenario experiment exhibits DVB-2C 8 VEIMBr can remove up to 93% of TcO 4 − from the simulated Hanford LAW scrubber solution. More importantly, DVB-2C 8 VEIMBr displays super acid and alkaline resistance and stability after immersing for 8 months under extreme conditions of 3 M HCl and 2 M NaOH. It can also effectively separate rhenium from molybdenum solution in the range of 3 M HCl - pH 2. Additionally, it still showed perfect regeneration performance after 10 cycles. In particular, this work demonstrates the feasibility of imidazolium-based ionic liquid adsorbents in the TcO 4 − or ReO 4 − immobilization process, which can be applied to capture these radioactive oxygen anions under high acid and high alkali conditions.

Investigation of Cu/Zn/Ag/Mo-based impregnated activated carbon for the removal of toxic gases, synthesized in aqueous media

Impregnated activated carbons (IACs) have been prepared successfully from aqueous solution of copper, zinc, silver and molybdenum for the removal of toxic gases from air. First, the activated carbon was impregnated by imbibing limit method with single metal, then a combination of 2 to 4 metals was used. The aim of this study was to access the adsorption capability of raw activated carbons (RAC) and IACs for SO2 and NO2 gases. Different techniques such as XRD, TEM, SEM, EDX mapping, AAS and BET surface area analyzer were used for characterization of materials. Results indicate that IACs provided satisfactory protection against challenge gases. Using the FTIR based gas analyzer, a significant increase in breakthrough time of all IACs was observed as compared to RAC. The maximum breakthrough time was achieved with four metals (Cu, Zn, Ag and Mo) impregnated on activated carbon i.e. 120.5 min for SO2 and 139.0 min for NO2, which were 13 and 25 times high respectively, in comparison with RAC. Adsorption capacity was found to be 320 mg SO2/g-C and 380 mg NO2/g-C. In comparison with RAC, ASZM2 carbon showed enhanced adsorption capability up to 30 times for SO2 and 40 times for NO2.

Seed germination of pea by seed treatment with mo nanoparticles

Article highlights the results of research of the effect of pre-sowing seed treatment with molybdenum nanoparticles solution on the process of germination of pea variety NS Moroz and determination of the optimal concentration of molybdenum solution, which has an maximal positive effect on growth processes during germination. The research was conducted in the Educational-Scientific Laboratory Demonstration Collection Field of Crops of the Department of Plant Science of the National University of Life and Environmental Sciences of Ukraine. Field and laboratory experiments were performed according to proven methods. Germination energy, germination and measurements of biometric parameters were determined. Water solution with molybdenum concentration of 1:100 provided the highest seed germination at the level of 99%, which has a positive effect in cultivation of peas, so field germination should also increase. The solution with Mo concentration of 1:10 had a positive effect on the length of the embryonic root of pea. It increased in length by 1.9 cm compare to control variant. Highest raw mass was formed by the treatment with Mo solution in concentration 1:100. This variant increased raw mass in stem by 0.06 g and 0.24 g in root system compare to control.

Ultrasound-assisted bimetallic NiMo nanocatalyst preparation using microemulsions for in-situ upgrading application: Impact on particle size

A new nanocatalyst preparation pathway, using ultrasound, for potential application to an in-situ upgrading technology (ISUT) is investigated. An ultrasonic probe is employed for preparing the transient microemulsions of the molybdenum solution with vacuum residue (VR), while high-shear mixing is used for preparation of microemulsions of nickel solution in VR. The results of catalyst preparation showed that the synthesized NiMo nanoparticles are half the size of the particles prepared conventionally using a high shear mixer for both metal precursors. The two prepared batches of suspended nanocatalysts in VR were then tested for evaluating their activity for upgrading reactions. In the upgrading tests, VR + cat and hydrogen were injected into a reactor packed with silica sand, where temperature, pressure and residence time were 350 °C, 7 MPa g, and 48 h, respectively for all experiments. Appreciable activity enhancement was observed for the ultrasound-assisted prepared nanoparticles. Using the new preparation method, the density and viscosity, as well as coking tendency of the products decreased, while the demetallization and desulphurization extent were both enhanced. Therefore, further ultrasound-aided NiMo nanoparticle preparations were carried out to investigate the effect of input sonication energy on the particle size.

Deposition and properties of mixed molybdenum sulfide (MoS2) and copper sulfide (CuxS) films on glass surface using elemental sulfur as a precursor

Mixed molybdenum sulfide (MoS2) and copper sulfide (CuxS) materials were synthesized on glass slides as a model substrate by successive ionic layer adsorption and reaction method using elemental sulfur as a sulfur source and solutions of copper (II/I) and molybdenum (IV) salts. X-ray diffraction data showed the presence of copper sulfides (anilite Cu7S4 and djurleite Cu31S16 phases), molybdenum disulfide and molybdenum oxide with adjustable crystalline phase composition dependent on the precursor exposure time and reaction temperature. Scanning electron microscopy images showed that the surface had a homogenous layer distribution at lower temperatures/short exposures and comprised of ~1 μm particles. X-ray photoelectron spectroscopy showed no oxidized sulfate (SO42−) compounds present on the sample surface while a thin MoO3 layer was found to cover the sample surface. Optical ultraviolet-visible spectroscopy showed mixed layers formed, containing optical properties of both MoS2 and CuxS. After annealing in an N2 atmosphere at 100 °C, the sample was composed primarily of MoS2 and copper sulfides in the crystalline phase with minimal residual S8. Usability of this mild mixed metal sulfide thin film preparation method on supports for sour natural gas catalyst synthesis is also discussed.

Selective transportation of molybdenum from model and ore through poly inclusion membrane

The extraction of molybdenum from the aqueous solution through poly inclusion membrane (PIM) containing tri-caprylylmethylammonium chloride (Aliquat-336) as a carrier has been investigated. A solution of molybdenum in phosphoric acid was used as a feed side while sodium hydroxide was used as stripping reagent. The results indicate that maximum flux value was obtained at 0.16 M Aliquat-336. Increase in H3PO4 concentration from 0.05 to 1.5 M results into an increase in molybdenum ions. The maximum flux of 3.00×10−6 mol/m2s through PIM was found at 1.5 M H3PO4. The optimized conditions were applied for removal of Mo(VI) from ore and more than 97 % Mo(VI) was extracted.
 
 Bull. Chem. Soc. Ethiop. 2020, 34(1), 93-104.
 DOI: https://dx.doi.org/10.4314/bcse.v34i1.9

Hydroconversion of Vacuum Residue of a Blend of Western Siberian Oils in the Presence of Ex Situ Synthesized Suspensions of Nanosized Catalysts

Concentrated suspensions of nanosized МоS2, МоS2+Ni7S6, Ni7S6, Fe1– xS, and (NH4)0.25 · WO3 particles with an average size of 273–364 nm have been synthesized from reverse emulsions of aqueous solutions of molybdenum, nickel, iron, and tungsten salts in the presence of a sulfiding agent and hydrogen in oil vacuum distillation residues and tested in oil vacuum distillation residue hydroconversion running in an autoclave and a pilot flow system. The test results have shown that the highest activity in hydrogenolysis reactions is exhibited by Mo-containing catalysts. The kinetic characteristics have been determined; the heat of the hydroconversion process has been calculated.

Assessment of the Activity of Dispersed Catalysts in Hydrocracking Reactions of Hydrocarbonaceous Feedstock

Concentrated suspensions of molybdenum, nickel, iron, and tungsten sulfide nanoparticles have been synthesized from inverse emulsions of aqueous solutions of molybdenum, nickel, iron, and tungsten salts in the presence of a sulfiding agent and hydrogen in a vacuum residue of oil distillation and have been tested in hydrocracking reactions of a mixture of paraffin wax and heavy cycle oil (HCO). The hydroconversion has been carried out in an autoclave at 445°C and a hydrogen pressure of 7 MPa. The results of the study have shown that the catalytic activity of the synthesized catalysts in cracking reactions increases in the order: MoS2, (MoS2 + Ni7S6), Ni7S6, Fe1 − xS, (NH4)0.25 ⋅ WO3.

Recycling of isotopically modified molybdenum from irradiated CerMet nuclear fuel: part 2—caesium separation from concentrated molybdate solution

Uranium-free molybdenum-based CerMet fuels can be applied for transmutation of minor actinides in GEN IV reactors or ADS. In a reprocessing concept designed in the first paper in this mini-series (Mares and John in J Radioanal Nucl Chem 320(1):227–233, 2019. https://doi.org/10.1007/s10967-019-06456-2 ) the residual radionuclidic impurities need to be separated from slightly alkaline (pH 9.1) highly concentrated ammonium molybdate solutions. Screening tests of technetium extraction onto three extraction chromatographic materials were performed in present study. Solid extractants based on Aliquat® 336 turned out to be the most promising for Tc extraction from molybdenum solutions both from the point of view of the extraction kinetics and the practical extraction capacity. The overall results of this mini-series allowed to conclude that if the molybdenum recycling concept proposed is adopted, separation of the residual radionuclidic impurities should not represent a significant problem.

Recovery of rhenium from aqueous mixed metal solutions by selective precipitation: A photochemical approach

Selective precipitation recovery of rhenium from aqueous solutions containing a coexisting metal (molybdenum, tungsten, or aluminum) by means of UV–visible light irradiation in the presence of 2-propanol and acetone was investigated. When the pH of the rhenium–molybdenum solutions (initial concentration 10.4 mM for each metal) was in the range from 6.3 to 12.5 and the irradiation time was 6 h, the rhenium in the initial solutions was efficiently recovered in the precipitates (92–99%), and the rhenium selectivity was high (the rhenium recovery ratio was 9.2–21 times that of molybdenum). The high selectivity for rhenium was also observed at different molybdenum concentrations (4.8–15.7 mM) and at a higher rhenium concentration (17.5 mM).Rhenium was also recovered efficiently and selectively from rhenium–tungsten solutions (initial concentration 10.4 mM for each metal): when the pH ranged from 7.0 to 12.0 and the irradiation time was 6 h, the rhenium recovery was 90–95% and the rhenium recovery ratio was 7.3–45 times that of tungsten. In contrast, when the coexisting metal was aluminum (initial rhenium and aluminum concentrations, 10.4 mM and 8.6 mM, respectively; pH 11.2), 95% of the rhenium was recovered in the precipitate after 6 h of irradiation; however, aluminum was somewhat unstable in the basic solution and the rhenium recovery ratio was 3.2 times that of aluminum. Unlike molybdenum and tungsten, aluminum tended to coprecipitate with rhenium.

Interaction of Structural Components of Titanium Composite in Vacuum at 1150°C

The interaction of a Ti + 10 Mo titanium alloy, which serves as a matrix in a tribological material, with calcium fluoride CaF2 and boron nitride BN, which play the role of a solid lubricant, during their heating and sintering in a vacuum of 10–3 Pa at 1150°C for 15 and 120 min, respectively, has been studied. In the heating of a Ti + 10 Mo + CaF2 model sample for 15 min and sintering of Ti + 10 Mo + CaF2 CAM1 for 120 min, calcium fluoride does not interact with the Ti + 10 Mo matrix and does not change its composition and structure; a transition layer between the matrix and solid lubricant does not form. Thus, calcium fluoride preserves its initial lubricating properties. In the sintering of Ti + 10 Mo + 13 CaF2 CAM1 for 120 min, a composite antifriction material with a microheterogeneous structure is synthesized. Its structure is a mixture of solid solutions of molybdenum in α- and β-titanium, which has a body-centered cubic lattice and face-centered hexagonal lattice, in which calcium fluoride CaF2 is distributed in the form of inclusions. In the heating of a Ti + 10 Mo + BN model sample for 15 min and sintering of Ti + 10 Mo + BN CAM2 for 120 min, the interaction of the Ti+10Mo alloy with boron nitride BN occurs to form a transition layer with the phase composition α-TiMo + TiB + TiN + BN. In the sintering of Ti + 10 Mo + BN CAM2 for 120 min, a composite material with a microheterogeneous structure is synthesized. Its structure is a solid solution of Mo in α-Ti with a face-centered hexagonal lattice, strengthened by products of interaction of titanium with nitrogen and boron, TiN and TiB, in which boron nitride BN is distributed in the form of inclusions.

Electrochemical deposition of bulk MoS2 thin films for photovoltaic applications

Layered transition metal dichalcogenides (TMDs) materials have shown high potential in many optoelectronic and photovoltaic applications due to their intriguing semiconducting properties. Most noticeably, the layered molybdenum disulfide (MoS2) has drawn much attention because of its unique layer-dependent band gap tunability and high electron mobility. A facile non-vacuum electrodeposition approach is used to deposit bulk MoS2 films onto FTO substrate immersed in an aqueous precursor solution of molybdenum and sulfur. The as-deposited and post-treated films are studied using X-ray diffraction, electron microscopy equipped with energy-dispersive x-ray spectroscopy, light absorption measurement, and X-ray photoelectron spectroscopy. Although the obtained gap energy values, 1.3–1.4 eV, of bulk MoS2 are indirect, the measured light absorption characteristic is high, especially above 1.7 eV. Also, electrochemical impedance spectroscopy studies of the films show that carrier concentration in higher than 1015 cm−3.

Single-phase mixed molybdenum-tungsten carbides: Synthesis, characterization and catalytic activity for toluene conversion

A series of single-phase mixed metal carbides of molybdenum and tungsten (Mo2-xWxC, 0 < x < 2) was synthesized. Precursors with intimately mixed metals were prepared by flash-freezing aqueous solutions of molybdenum and tungsten salts in liquid nitrogen and subsequent freeze-drying. The powders of freeze-dried samples had small particles that facilitated reduction and carburization. Direct carburization of freeze-dried precursors at a final temperature of 650 °C resulted in formation of single-phase metal carbides with hexagonal structures and CO adsorption capacities of 15–27 μmol/g. All carbides were catalytically active for conversion of toluene at a total pressure of 21 bar, and a H2:toluene molar ratio of 33. At a reaction temperature of 250 °C, only methylcyclohexane formed at TOFs of 0.13 (Mo0.5W1.5C) ― 2.1 s−1 (Mo2C). Activation energies for ring hydrogenation were in the range of 40–60 kJ/mol. At 400 °C, catalysts deactivated for 24 h before stabilizing. At steady state, methylcyclohexane and small alkanes formed via ring hydrogenation and hydrogenolysis, indicating the presence of sites with metallic character. Disproportionation of toluene to benzene and xylenes indicated the presence of weakly acidic sites. An excess of benzene was attributed to the presence of carbon vacancies on the surface, which formed more readily in the tungsten-containing carbides.