Journal articles: 'Molybdenum'

1

Halmi, M. I. E., and Siti Aqlima Ahmad. "Chemistry, biochemistry, toxicity and pollution of molybdenum: A mini review." Journal of Biochemistry, Microbiology and Biotechnology 2, no. 1 (July 31, 2014): 1–6. http://dx.doi.org/10.54987/jobimb.v2i1.122.

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Molybdenum is used in various industries. Its pollution has been recorded globally and is an emerging pollutant. Molybdenum is poorly represented in the literature as compared to heavy metals such as mercury, chromium, arsenic, lead and cadmium for instance, due to the metalâ€™s low toxicity to humans. It has now been reported that molybdenum is very toxic to embryo and spermatogenesis of fish and mice and this worrying trend would place molybdenum at the forefront of toxicology and bioremediation studies in the future. This mini review attempts to summarize what we know on its chemistry, biochemistry, toxicity and pollution with the hope that this knowledge would be useful for future studies on molybdenumâ€™s removal from the environment.Â

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2

Choi, Byeong-Min, Seok-Hwan Son, Chul-Wee Lee, Sun-Yeong Park, and Min-Chul Chung. "Characterization and Synthesis of Molybdenum Metal Precursors for Hydrocracking Reaction of Vacuum Residues." Journal of Nanoscience and Nanotechnology 20, no. 9 (September 1, 2020): 5787–90. http://dx.doi.org/10.1166/jnn.2020.17650.

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In this study, Molybdenum precursors were synthesized with Triphenylphosphine, 1,2-Bis(diphenylphosphino)ethane, Pyridine, 2,2-Bipyridine as a ligands. The molybdenum precursors was used for Hydrocraking reaction of Vacuum Residue (VR). Hydrocracking reactions were carried out under the 430 °C and H2 pressure of 80 bar in an 100 ml high pressure reactor. New Molybdenum precursors were tested and their activities were compared with Mo-octoate. The Molybdeum-Phosphine precursor showed the best performances, high yield and low coke contents (below 0,5 wt%), in of hydrocracking for VR. To characterize the physicochemical properties of Moprecursor catalyst, various characterization techniques (NMR, XPS) were carried out. We confirmed that cokes in the reactor were contained the P atoms derived from ligand of Mo-precursor after hydrocracking of VR.

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3

Klienkov, Alexey V., and Alexander A. Petukhov. "Obtaining molybdenyl glycolate using ethanol as a salting out solvent." Butlerov Communications 59, no. 9 (September 30, 2019): 66–70. http://dx.doi.org/10.37952/roi-jbc-01/19-59-9-66.

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The global production of propylene oxide is more than 8 million tons/year and is increasing by more than 5% annually. Almost all domestic propylene oxide (72 thousand tons/year) is produced at PJSC Nizhnekamskneftekhim (Russia) according to one of the variants of the Halcon process – epoxidation of propylene with ethylbenzene hydroperoxide (HPEB) in the presence of a molybdenum catalyst. One of the most important tasks arising in improving the process for the joint production of styrene and propylene oxide at PJSC Nizhnekamskneftekhim (Russia) is the search and development of new catalysts and catalytic systems, one of the stages of this process – the epoxidation of propylene with HPEB. The complex molybdenum catalyst used in the production of propylene oxide, having high activity and selectivity, has several disadvantages, namely: low dissolved molybdenum content, high consumption of ethylbenzene hydroperoxide for its production, and instability during storage. Thus, the problem of obtaining a catalyst with a higher content of dissolved molybdenum and increasing the stability of the catalytic complex, i.e. development of new catalytic systems with the best technological and technical and economic indicators. An analysis of the scientific and technical literature and patent publications showed that in the synthesis of a complex molybdenum catalyst, various molybdenum compounds of both organic and inorganic nature can be used. During the study, molybdenum-containing solutions based on ammonium paramolybdate and monoethylene glycol were tested, distillation distillation products prepared by distilling off excess monoethylene glycol by strengthening under vacuum. Molybdenyl glycolate was isolated by salting out with ethanol from a distillation bottoms product.

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4

Bougié, D., J. Voirin, F. Bureau, J. F. Duhamel, G. Mutter, and M. Drosdowsky. "Molybdenum." Acta Paediatrica 78, no. 2 (March 1989): 319–20. http://dx.doi.org/10.1111/j.1651-2227.1989.tb11079.x.

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5

MITCHELL, PHILIP C. H. "MOLYBDENUM." Chemical & Engineering News 81, no. 36 (September 8, 2003): 108. http://dx.doi.org/10.1021/cen-v081n036.p108.

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6

Novotny, Janet A., and Catherine A. Peterson. "Molybdenum." Advances in Nutrition 9, no. 3 (May 1, 2018): 272–73. http://dx.doi.org/10.1093/advances/nmx001.

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7

Barceloux, Donald G., and Donald Barceloux. "Molybdenum." Journal of Toxicology: Clinical Toxicology 37, no. 2 (January 1999): 231–37. http://dx.doi.org/10.1081/clt-100102422.

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8

Minelli, Martin M. "Molybdenum." Coordination Chemistry Reviews 81 (November 1987): 1–49. http://dx.doi.org/10.1016/0010-8545(87)85012-9.

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9

Schwarz, Günter, and Ralf R. Mendel. "MOLYBDENUM COFACTOR BIOSYNTHESIS AND MOLYBDENUM ENZYMES." Annual Review of Plant Biology 57, no. 1 (June 2006): 623–47. http://dx.doi.org/10.1146/annurev.arplant.57.032905.105437.

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10

Turnlund, Judith R., and William R. Keyes. "Plasma molybdenum reflects dietary molybdenum intake." Journal of Nutritional Biochemistry 15, no. 2 (February 2004): 90–95. http://dx.doi.org/10.1016/j.jnutbio.2003.10.003.

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11

Saji, Viswanathan S., and Chi-Woo Lee. "Molybdenum, Molybdenum Oxides, and their Electrochemistry." ChemSusChem 5, no. 7 (June 12, 2012): 1146–61. http://dx.doi.org/10.1002/cssc.201100660.

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12

Wang, Hong Ming, Xiao Jian Fan, Gui Rong Li, Wei Wen Chen, Lei Cao, and Yang Li. "Experiment on Direct Smelting and Alloying Process between High-Carbon Ferrochrome and Molybdenum Oxide." Applied Mechanics and Materials 633-634 (September 2014): 116–19. http://dx.doi.org/10.4028/www.scientific.net/amm.633-634.116.

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Based on the direct reduction alloying theory, experiments on chromium molybdenum alloy prepared through the direct reduction and alloying reactions between the high-carbon ferrochrome and molybdenum oxide were conducted in a laboratory scale. The critical factors that would impact the reduction rate of molybdenum oxide and the yield rate of molybdenum were analyzed. The results indicate that the reduction rate of molybdenum oxide can exceed 90%, meanwhile, the yield rate of molybdenum is affected by many factors and fluctuates in a wide range. As temperature rising, the reduction rate of molybdenum oxide is increased whereas the yield rate of molybdenum is decreased. With the amount of molybdenum oxide added increasing, the reduction rate of molybdenum oxide and yield rate of molybdenum are decreased simultaneously. Making slag during melting process and molybdenum oxide roasted by addition of lime are effective measures to improve the yield rate of molybdenum.

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13

Novotny, Janet A. "Molybdenum Nutriture in Humans." Journal of Evidence-Based Complementary & Alternative Medicine 16, no. 3 (May 2, 2011): 164–68. http://dx.doi.org/10.1177/2156587211406732.

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Molybdenum is a trace element that functions as a cofactor for at least 4 enzymes: sulfite oxidase, xanthine oxidase, aldehyde oxidase, and mitochondrial amidoxime reducing component. In each case, molybdenum is bound to a complex, multiring organic component called molybdopterin, forming the entity molybdenum cofactor. The best sources of dietary molybdenum are legumes, grains, and nuts. Bioavailability of molybdenum is fairly high but depends on form, with molybdenum preparations having greater bioavailability than food-bound molybdenum. Molybdenum deficiency and toxicity are rare, possibly because of the body’s ability to adapt to a wide range of molybdenum intake levels. At low intakes of molybdenum, the fractional transfer of molybdenum from plasma to urine is lower and a greater fraction is deposited into tissues, and at high intakes of molybdenum, the opposite occurs. Molybdenum has proven to be an interesting trace mineral that is essential for life.

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14

Galevskii, G. V., O. A. Polyakh, V. V. Rudneva, and A. E. Anikin. "Analysis of the current state of molybdenum mineral and raw material base, mining and processing of molybdenum-containing ores." Ferrous Metallurgy. Bulletin of Scientific , Technical and Economic Information 76, no. 7 (August 11, 2020): 665–75. http://dx.doi.org/10.32339/0135-5910-2020-7-665-675.

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Molybdenum has a complex of practically significant properties and is widely used for alloying steels and cast irons, in the composition of alloys of various purposes, as well as a structural material in pure form. Molybdenum belongs to the group of rare metals, which causes the relevance of analytical research of the modern state of the mineral- raw material base of molybdenum, extraction and processing of molybdenum-containing ores. The results of analysis of the mineral-raw material base of molybdenum of foreign countries and Russia, assessment of prospects of its expansion are presented. The confirmed world molybdenum resources amount to 12 million tons, including domestic – 2 million tons. 75% of molybdenum reserves are concentrated in the USA, China, Chile, Peru and Canada. Description of the types of deposits of molybdenum, copper-molybdenum and molybdenum-tungsten ores, the main types of molybdenum minerals has been quoted. Methods of ore concentration of various composition for production of molybdenum concentrates, additional enrichment of molybdenum concentrate and industrial practice of molybdenum concentrate processing are considered. In terms of ore quality domestic and foreign raw material base of molybdenum are comparable. 63% of domestic production of molybdenum-containing ores is provided by OJSC “Sorsky GOK”, 33% – OJSC “Zhirekenskiy GOK”. These enterprises produce molybdenum concentrates of grades КМФ-5, КМФ-6, КМФ-7. Their production capacity is about 12 thousand tons of concentrate per year. Molybdenum concentrates are processed by pyro- and hydrometallurgical methods and are an industrial product for production of ferromolybdenum and its chemical compounds. The total capacity of molybdenum concentrate processing plants is 300 thousand tons per year.

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15

Feng, Han Kun, Zong Ying Cai, Yun Gang Li, and Yan Fei Qi. "Domestic and Overseas Research Status on Molybdenum Resources and its Use." Advanced Materials Research 834-836 (October 2013): 401–6. http://dx.doi.org/10.4028/www.scientific.net/amr.834-836.401.

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According to physicochemical property of molybdenum, the application of molybdenum is elaborated from three aspects that are molybdenum element, molybdenum alloys and molybdenum compound; The distribution of nature resource of molybdenum at abroad and home and the source of recoverable resources are summarized; the production method of ammonium molybdate is introduced which are oxidation roasting and wet oxidation, and the extracting method of molybdenum is introduced which is reduction method; the development tendency of molybdenum is pointed out.

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16

Lee, Jeong-Ick. "A Study on the Manufacturing of Molybdenum Pins for Electrodes." Turkish Journal of Computer and Mathematics Education (TURCOMAT) 12, no. 6 (April 10, 2021): 704–11. http://dx.doi.org/10.17762/turcomat.v12i6.2075.

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The molybdenum cup and molybdenum pin, which are the main materials of the molybdenum electrode used for the LCD BLU CCFL electrode, have not been developed in Korea and imported from Japan. In this paper, especially, research on prototype manufacturing and CAE analysis is performed to develop a molybdenum pin. In this research, to develop the manufacturing technology of molybdenum pin used for CCFL electrode of LCD BLU, development of linear processing technology, development of molybdenum wire surface treatment technology, development of wire cutting technology, production of molybdenum pin, design and fabrication of JIG and Fixture for inspection, molybdenum pin prototyping and analysis, and development of 100% molybdenum pin inspection technology. The development of molybdenum pins developed through this research can overcome Japan's technological level, which depends entirely on imports from Japan, and it is thought that the development will have a significant impact on the overall industry using molybdenum pins.

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17

Jia, Qing Mei, Li Min Zhang, and Wen Zhi Lv. "Experimental Study on the Mineral Processing of a Certain Low Grade Copper-Molybdenum Ore in Xinjiang." Advanced Materials Research 535-537 (June 2012): 983–86. http://dx.doi.org/10.4028/www.scientific.net/amr.535-537.983.

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Copper molybdenum ore, Experiment study, Copper molybdenum separation, Flotation. Abstract. Aimed at the ore characteristics，the flotation flowsheet of one—stage coarse grinding—bulk flotation of copper and molybdenum—regrinding of bulk concentrate—separation of copper and molybdenum was determined effected．Experiment uses the above flowsheet and reasonable conditions to process molybdenum crude ore of molybdenum and copper crude grade being 0.066% and 0.03%,and the better indexes of the molybdenum grade of concentrate is 51.68%,the copper grade of concentrate is 12.60% and molybdenum recovery is 74.33% are got.

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18

Xiao, Ri Peng, Bo Yang, and Tao He. "Application of New Inhibitor on Separating Copper-Molybdenum Ore from Jinping." Applied Mechanics and Materials 713-715 (January 2015): 2590–93. http://dx.doi.org/10.4028/www.scientific.net/amm.713-715.2590.

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Based on the symbiotic and dissemination relationship of a copper-molybdenum ore in Tibet,developed a beneficial flotation flowsheet —first step was copper-molybdenum mixed flotation and then copper-molybdenum were separated. Copper-molybdenum mixed flotation used conventional flotation reagents. Copper-molybdenum separation used new reagent-- HX-1 for copper inhibitor. Experiments show that HX-1 was good to the copper-molybdenum separation. The content of copper was decreased to 0.03% in molybdenum concentrate.

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19

Mitran, Gheorghiţa, Shaojiang Chen, and Dong-Kyun Seo. "Molybdenum Dopped Copper Ferrites as Active Catalysts for Alcohols Oxidative Coupling." Materials 12, no. 11 (June 10, 2019): 1871. http://dx.doi.org/10.3390/ma12111871.

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Copper ferrites dopped with molybdenum were studied in an oxidative coupling reaction between methanol and ethanol in the gas phase. The catalysts have been characterized by X-ray diffraction, where the presence of ferrite, magnetite, and tenorite phases was observed; scanning electron microscopy; UV-Vis spectroscopy; and Fourier-transform infrared spectroscopy, which highlighted the presence of octahedral coordination of isolated molybdena species. The catalyst with the highest activity in this reaction and with the highest selectivity to hydroxyacetone is the one that presents Lewis sites with weak acidity. The methyl and ethyl acetate selectivities are directly proportional to the Cu/Fe ratio. It has been observed that the presence of reduced copper sites is responsible for the selectivity in esters, while the presence of reduced iron and molybdenum sites is responsible for the acetol production.

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20

Schulzke, Carola, and Christian Fischer. "Molybdenum and tungsten oxidoreductase model chemistry." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C1372. http://dx.doi.org/10.1107/s2053273314086276.

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After introducing the general topic of molybdenum and tungsten dependent oxidoreductases[1] our group's strategic approaches relating to issues posed by the structures and functions of these enzymes' cofactors will be presented. Cofactor related questions will be discussed in detail which, at least to some extent, could be answered by model synthesis and crystallographic plus spectroscopic and/or electrochemical evaluation. These are in particular the influence, the type of coordination to the peptide may have on the catalytic performance, the choice of metal (molybdeum versus tungsten) in these enzymes and the respective evolutionary change in preference.[2,3] Finally some exciting and entirly unanticipated crystallographic discoveries will be presented.These are for instance unusual binding motifs, coordination polymer structures, hydrogen bonding and additional non-covalent interactions between dithiolene sulfur ligand atoms and potassium and sodium counter ions.

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21

Karimova, L., Y. Kairalapov, T. Tussupbekova, T. Oleinikova, and G. Makasheva. "Hydrometallurgical processing of molybdenum middlings from Shatyrkul-Zhaysan cluster ore." Journal of Mining and Metallurgy, Section B: Metallurgy, no. 00 (2024): 6. http://dx.doi.org/10.2298/jmmb230725006k.

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This research investigates the hydrometallurgical processing of molybdenum middlings extracted from copper-molybdenum ore at the Shatyrkul-Zhaysan cluster in Kazakhstan. Molybdenum intermediate product obtained after selective flotation of the copper-molybdenum concentrate was used, with 0.07% yield, 22.23% molybdenum content, and 74.91% extraction. Mineralogical analysis shows molybdenite and chalcopyrite as the main minerals. Experiments study atmospheric leaching with nitric acid in single-stage and two-stage countercurrent modes to optimize molybdenum extraction and reduce acid consumption. The optimal conditions obtained were: 300 g/L nitric acid, 100 g/L sulfuric acid, 90?C temperature, and 2 hours leaching time in single stage leaching, giving 98.8% molybdenum extraction. Two-stage leaching under optimized conditions allows obtaining 94.3% molybdenum extraction in solutions with lower residual acidity (0.89 g-eq/L) and redox potential (550 mV) without reducing valuable component extractions. Molybdenum extraction reaches 94.3% in the subsequent solvent extraction stage from two-stage leaching solutions. The final product, calcium molybdate containing 46.83% molybdenum, meets commercial grade specifications. This research demonstrates an effective process for the hydrometallurgical production of commercial calcium molybdenite from copper-molybdenum ore, with high molybdenum recovery, reduced acid consumption through two-stage leaching, and minimal hazardous discharges.

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22

Govindarajan, S., B. Mishra, D. L. Olson, J. J. Moore, and J. Disam. "Synthesis of molybdenum disilicide on molybdenum substrates." Surface and Coatings Technology 76-77 (November 1995): 7–13. http://dx.doi.org/10.1016/0257-8972(95)02524-3.

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23

Novotny, Janet A., and Judith R. Turnlund. "Molybdenum Intake Influences Molybdenum Kinetics in Men." Journal of Nutrition 137, no. 1 (January 1, 2007): 37–42. http://dx.doi.org/10.1093/jn/137.1.37.

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24

Shi, Tingyu, and Jianping Xie. "Molybdenum enzymes and molybdenum cofactor in mycobacteria." Journal of Cellular Biochemistry 112, no. 10 (September 19, 2011): 2721–28. http://dx.doi.org/10.1002/jcb.23233.

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25

Gavrilova, Natalia, Maria Myachina, Victor Nazarov, and Valery Skudin. "Simple Synthesis of Molybdenum Carbides from Molybdenum Blue Nanoparticles." Nanomaterials 11, no. 4 (March 30, 2021): 873. http://dx.doi.org/10.3390/nano11040873.

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In recent years, much attention has been paid to the development of a new flexible and variable method for molybdenum carbide (Mo2C) synthesis. This work reports the applicability of nano-size clusters of molybdenum blue to molybdenum carbide production by thermal treatment of molybdenum blue xerogels in an inert atmosphere. The method developed made it possible to vary the type (glucose, hydroquinone) and content of the organic reducing agent (molar ratio R/Mo). The effect of these parameters on the phase composition and specific surface area of molybdenum carbides and their catalytic activity was investigated. TEM, UV–VIS spectroscopy, DTA, SEM, XRD, and nitrogen adsorption were performed to characterize nanoparticles and molybdenum carbide. The results showed that, depending on the synthesis conditions, variants of molybdenum carbide can be formed: α-Mo2C, η-MoC, or γ-MoC. The synthesized samples had a high specific surface area (7.1–203.0 m2/g) and meso- and microporosity. The samples also showed high catalytic activity during the dry reforming of methane. The proposed synthesis method is simple and variable and can be successfully used to obtain both Mo2C-based powder and supports catalysts.

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26

Moser, Mathias, Sylvain Lorand, Florian Bussiere, Frédéric Demoisson, Hervé Couque, and Frédéric Bernard. "Influence of Carbon Diffusion and the Presence of Oxygen on the Microstructure of Molybdenum Powders Densified by SPS." Metals 10, no. 7 (July 14, 2020): 948. http://dx.doi.org/10.3390/met10070948.

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Due to molybdenum’s Body-Centered Cubic (BCC) crystalline structure, its ductile–brittle transition temperature is sensitive to shaping, purity and microstructure. Dense molybdenum parts are usually shaped by the powder metallurgy process. The aim of this work concerns the spark plasma sintering of high-purity powders prepared by inductively coupled plasma. The influence of carbon diffusion and its interaction with oxygen on the density (i.e., the densification stage) and on the microstructure (i.e., the grain growth stage) during spark plasma sintering was investigated. The formation of carbide is usually expected for a sintering temperature above 1500 °C leading to grain growth (e.g., more than 10 times larger than the initial powder grain size after sintering at 1900 °C for 10 min). The brittleness was also affected by the segregation of molybdenum carbides at the grain boundaries (i.e., intergranular brittle fracture). Consequently, to reduce the sintering temperature to below 1500 °C, mechanically activated powders were used. From these milled powders, a dense molybdenum disc (60 mm in diameter and 10 mm in thickness) sintered at 1450 °C under a pressure of 70 MPa for 30 min was obtained. It is composed of a fine microstructure without carbide and oxide, its ductility is close to 13% with a maximum resistance of 550 MPa.

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27

Gurbanova, U. M. "ELECTODEPOSITION OF MOLYBDENUM FROM ALKALI ELECTROLYTE." Azerbaijan Chemical Journal, no. 4 (December 12, 2019): 59–64. http://dx.doi.org/10.32737/0005-2531-2019-4-59-64.

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28

Shen, Yirui, Pingping Jiang, Phyu Wai, Qian Gu, and Weijie Zhang. "Recent Progress in Application of Molybdenum-Based Catalysts for Epoxidation of Alkenes." Catalysts 9, no. 1 (January 2, 2019): 31. http://dx.doi.org/10.3390/catal9010031.

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Epoxides are important industrial intermediates applied in a variety of industrial processes. During the production of epoxides, catalysts have played an irreplaceable and unique role. In this review, the historic progress of molybdenum-based catalysts in alkene epoxidation are covered and an outlook on future challenge discussed. Efficient catalysts are demonstrated including soluble molybdenum complexes, polyoxometalates catalysts, molybdenum-containing metal organic frameworks, silica supported molybdenum-based catalysts, polymer supported molybdenum-based catalysts, magnetic molybdenum-based catalysts, hierarchical molybdenum-based catalysts, graphene-based molybdenum containing catalysts, photocatalyzed epoxidation catalysts, and some other systems. The effects of different solvents and oxidants are discussed and the mechanisms of epoxidation are summarized. The challenges and perspectives to further enhance the catalytic performances in alkenes epoxidation are presented.

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29

Zhang, Guo Jun, Jun Zhuo, and Shu Ai Ren. "Microstructure and Mechanical Properties of Molybdenum Alloys Doped with ZrB₂ Particles." Advanced Materials Research 160-162 (November 2010): 1828–33. http://dx.doi.org/10.4028/www.scientific.net/amr.160-162.1828.

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The molybdenum alloys doped with various mass fraction zirconium diboride (ZrB2) particles were successfully prepared by using the powder metallurgy technology. The microstructure, hardness and the tensile properties of the pure molybdenum and molybdenum alloys doped with ZrB2 particles were determined at room temperature. Results showed that the addition of zirconium diboride refined the molybdenum grains obviously, meanwhile, molybdenum grain sizes decrease with the increasing of zirconium diboride mass fraction. Measurements on mechanical properties showed that molybdenum alloys doped with ZrB2 particles had higher hardness and strength than pure molybdenum. The analysis and discussion results show that the strengthening mechanisms of ZrB2-doped molybdenum alloys may be attributed to the fine-grain strengthening, particle dispersion strengthening, interfacial-bond strengthening and oxygen reduction strengthening.

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30

Li, Feng Jiu, Li Min Zhang, and Wen Zhi Lv. "Experimental Study on the Mineral Processing of a Certain Low Grade Copper-Molybdenum Ore in XINJIANG." Advanced Materials Research 557-559 (July 2012): 75–79. http://dx.doi.org/10.4028/www.scientific.net/amr.557-559.75.

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Aimed at the ore characteristics，the flotation flowsheet of one—stage coarse grinding—bulk flotation of copper and molybdenum—regrinding of bulk concentrate—separation of copper and molybdenum was determined effected．Experiment uses the above flowsheet and reasonable conditions to process molybdenum crude ore of molybdenum and copper crude grade being 0.066% and 0.03%,and the better indexes of the molybdenum grade of concentrate is 51.68%,the copper grade of concentrate is 12.60% and molybdenum recovery is 74.33% are got.

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31

Zhao, Yi, Xuejun Feng, Yaoming Xie, R. Bruce King, and H. F. Schaefer. "Molybdenum–Molybdenum Multiple Bonding in Homoleptic Molybdenum Carbonyls: Comparison with Their Chromium Analogues." Journal of Physical Chemistry A 116, no. 23 (May 31, 2012): 5698–706. http://dx.doi.org/10.1021/jp302272q.

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32

Shukor, M. Y., N. A. Shamaan, and M. A. Syed. "Effect of Metal Ions on the Molybdenum-Reducing Activity of S. marcescens strain DrY6." Journal of Environmental Microbiology and Toxicology 1, no. 1 (December 26, 2013): 5–8. http://dx.doi.org/10.54987/jemat.v1i1.17.

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Microbial metal reduction of molybdenum to molybdenum blue can be used in the bioremediation of molybdenum contaminated environment. A molybdenum-reducing strain, S. marcescens strain Dr.Y6, was tested for its molybdenum-reduction capability in the presence of several metal ions such as Cr6+, Fe3+, Fe2+, Zn2+, Mg2+, Co2+,Ni2+,Cd2+, Ag+, Mn2+, Cu2+, Hg2+, Pb2+and Sn2+. Metal ions such as chromium, copper and mercury caused 88.4, 98.8 and 88.3% inhibition of the molybdenum-reducing activity, respectively, indicating the presence of a thiol group in the molybdenum-reducing enzyme of this bacterium. However, two ions, ferrous and stannous, markedly increased the activity of molybdenum-reducing activity in this bacterium in the control studies suggesting that these metal ions could produce false positive results and their use should be accompanied with proper control.

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33

Osipov, P. A., R. A. Shayakhmetova, and A. B. Sagyndykov. "Preparation, purification and dissolution of molybdenum oxychloride compounds in water." Engineering Journal of Satbayev University 144, no. 6 (2022): 18–23. http://dx.doi.org/10.51301/ejsu.2022.i6.03.

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Expansion of the fields of application of molybdenum and its compounds of high purity requires the study of their various purification methods. The paper considers low-temperature chlorination of technical molybdenum dioxide, purification of the gas mixture from impurities in the filter system, condensation and dissolution of purified molybdenum oxychloride compounds in water. On filters made of tableted sodium chloride, gaseous molybdenum dioxide is purified from aluminum, iron, chromium and nickel with the formation of low-volatile compounds. The capture of silicon by this filter was not detected. Purification of tungsten on filters of granular molybdenum oxide practically does not occur. Purified molybdenum oxychloride compounds are desublimated in the form of compact and fluffy products with an underestimated chlorine content relative to the stoichiometric composition of molybdenum dioxide. Compact molybdenum oxychloride compounds dissolve in distilled water with little or no precipitation. When dissolving fluffy compounds of molybdenum, a tangible precipitate is formed, into which a significant part of the impurities passes.

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34

Tokasheva, D. S., M. K. Beisekova, K. E. Zhanassova, Zh B. Tleukulova, A. Zh Akbasova, and R. T. Omarov. "Influence of various molybdenum, tungsten, and molybdenum with tungsten concentrations to the growth of Nicotiana Benthamiana." BULLETIN of the L.N. Gumilyov Eurasian National University. BIOSCIENCE Series 137, no. 4 (2021): 84–91. http://dx.doi.org/10.32523/2616-7034-2021-137-4-84-91.

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Molybdenum is a key microelement in plant functioning, as it takes part in oxidation-reduction reaction of nitrogen and sulphuric exchange, plant hormone biosynthesis, and xenobiotic detoxication. Molybdenum deficiency is widely spread among pulses and some vegetable crops, which are intensively irrigated, or which grow in acid or sandy soils. Plant cells can absorb molybdenum in the form of molybdate oxyanion. Even though molybdenum is available for a cell, it is biologically inactive element until there is a formed complex of molybdenum co-factor (Moco). Moco is situated in the active center of molybdenum ferments, which are used as short bonds of electron passage and take part in nitrogen and sulfur metabolism, hormone biosynthesis, and plant harmful bond detoxification. There are known four molybdenum ferments of higher plants such as nitrate reductase (NR), xanthine dehydrogenase (XDH), aldehyde oxidase (AO), and sulfite oxidase (SO). Tungsten (T) is molybdenum antagonist. It pushes molybdenum out of mobdoenzymes, as a result molybdenum-containing enzymes become inactive. Molybdenum is a vital element which is in minimal qualities required for plant growth and development. On the other hand, huge amount of Molybdenum is toxic, and its complete absence is lethal for the plant organism. As a result, the search for the perfect molybdenum concentration for the growth and development plays an important role in agriculture. Nicotiana Benthamiana, or Australian tobacco was used as a model plant, it is nightshade family (Solanaceae). The article presents sodium molybdate (Na2MoO4•2H2O), sodium wolframate (Na2WO4•2H2O), and molybdate with wolframate influence to germinating capacity and length of Nicotiana Benthamiana plantlets.

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35

Halmi, M. I. E., S. A. Ahmad, M. T. Yusof, Mohd Yunus Shukor, and M. A. Syed. "Short Communication: Entrapment of Mo-Reducing Bacterium Increase Its Resistance towards Heavy Metals." Bulletin of Environmental Science and Sustainable Management (e-ISSN 2716-5353) 1, no. 1 (December 27, 2013): 11–13. http://dx.doi.org/10.54987/bessm.v1i1.21.

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Molybdenum is highly toxic to ruminant at several ppm. Molybdenum pollution in soil and mine tailings could reach 20,000 ppm in the most contaminated region. Molybdenum is mined as a byproduct of copper in malaysia and occasional elevated levels of these heavy metals have been reported. Bioremediation of molybdenum in the presence of the toxic copper is a challenge. In this work a novel method of molybdenum removal from aqueous solution using the dialysis tubing method coupled with molybdenum-reducing activity of serratia sp. Strain dry5 is demonstrated. The enzymatic reduction of molybdenum is molybdenum blue, a colloid that does not pass through dialysis tubing. The calculated maximal rate of molybdenum blue production (vmobluemax) was 0.264Â±0.034 mmole/mo-blue/hr and the concentration of molybdate resulting in the halfmaximal rate of reduction (kmo) was 21.78Â±3.89 mM molybdate indicating an efficient system with high tolerance towards molybdenum. Heavy metals exhibited significantly higher inhibition towards free cells compared to dialysis tubing entrapped cells. Hence the immobilization of moreducing cells by entrapment could be a viable bioremediation tool in aquatic bodies or effluentco-contaminated by other heavy metals.

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36

Li, Geng. "Electrochemical Sensor under Nanostructured Materials." Key Engineering Materials 852 (July 2020): 70–79. http://dx.doi.org/10.4028/www.scientific.net/kem.852.70.

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In order to study the electrochemical sensor of nanometer mechanism materials to realize the high sensitive detection of different chemical molecules, in this research, the preparation methods of molybdenum dioxide nanomaterials, molybdenum dioxide/metal particles (Au, Pt, Au@Pt) composites and the preparation of molybdenum dioxide nanomaterials, molybdenum dioxide /Au composite nanomaterials, molybdenum dioxide /Pt composite nanomaterials and molybdenum dioxide /Au @Pt composite nanomaterials were introduced. Then the electrochemical behavior of several modified electrodes, electrochemical behavior in catechol system, scanning and pH were applied to the modified electrode. Finally, the electrode p-catechol system was detected by differential pulse voltammetry and the actual samples were analyzed. The results showed that compared with unmodified electrode materials, the electrode modified by molybdenum dioxide nanomaterials, molybdenum dioxide /Au composite nanomaterials, molybdenum dioxide /Pt composite nanomaterials and molybdenum dioxide /Au @Pt composite nanomaterials has better electrocatalytic performance and the detection of catechol has a good effect. Among them, the electrochemical sensor constructed by MoS2-Au@Pt composite has the best detection performance for catechol. The results have a good guiding significance for the performance improvement of electrochemical sensor.

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Feng, Qi Cheng, Shu Ming Wen, Wen Juan Zhao, Ci Yun Chen, and He Fei Zhao. "Recovery of Molybdenum from Molybdenum Ore with a High Content of Carbon by Separating Carbon from Sulfur." Advanced Materials Research 634-638 (January 2013): 3450–53. http://dx.doi.org/10.4028/www.scientific.net/amr.634-638.3450.

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The study was aimed to recover molybdenum minerals from molybdenum ore with a high content of carbon by flotation process. The material belonged to a kind of refractory molybdenum ore from which molybdenum minerals could not be extracted effectively using traditional beneficiation and metallurgy, because of their similar floatability between carbon minerals and molybdenite and complex intergrowth. Based on the research on the properties of the material and lots of experiments, the carbon-molybdenum bulk flotation experiment was firstly carried out to concentrate molybdenum, and then some potassium permanganate and lime were added in carbon-molybdenum bulk flotation products to inhibit sulfide minerals along with appropriate air agitation. Under such a condition, the floatability of sulfide minerals was weakened and carbon was separated from sulfur. Then carbon concentrate and sulfur concentrate were used to extract molybdenum through metallurgy respectively.

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38

Thompson, K. H., K. C. Scott, and J. R. Turnlund. "Molybdenum metabolism in men with increasing molybdenum intakes: changes in kinetic parameters." Journal of Applied Physiology 81, no. 3 (September 1, 1996): 1404–9. http://dx.doi.org/10.1152/jappl.1996.81.3.1404.

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Molybdenum metabolism was studied in four young men to determine the effect of the amount of dietary molybdenum on molybdenum kinetics. A compartmental model, developed by using data from a study with low dietary molybdenum, was adapted to accommodate five levels of molybdenum. Each level, ranging from 22 to 1,470 micrograms molybdenum/day, was fed for 24 days. Kinetics of absorption and excretion were traced by using 97Mo (intravenous) and 100 Mo (oral) stable-isotope tracers at selected intervals. Urinary and fecal isotope excretion data for 6-day pooled collections were fit to a kinetic model by using SAAM/CONSAM software. Residence times for molybdenum were estimated at 2.4 days in the gastrointestinal tract, 40 min in plasma, from 3.3 to 0.3 days in fast-turnover tissue, and from 63 to 237 days in slow-turnover tissue. As dietary molybdenum increased, residence time decreased in fast-turnover tissue and increased in slow-turnover tissue. The model closely approximated the highly efficient homeostatic mechanisms of molybdenum metabolism over a wide range of intakes.

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Kamlesh, Joshi, Hassan Jayaraj Amarendra, Gajanan Prabhakar Chaudhari, and Sameer Kumar Nath. "Effect of Deposition Parameters & Molybdenum Percentage on Nickel-Molybdenum Alloy Coatings." Advanced Materials Research 585 (November 2012): 493–97. http://dx.doi.org/10.4028/www.scientific.net/amr.585.493.

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The use of Potassium-phosphate baths for the alloy deposition of Nickel–Molybdenum is recently proved equally good as Sodium-citrate baths. The coatings so obtained from Potassium-phosphate baths were examined for atomic weight percentage of Molybdenum. The variation in weight percentage of Molybdenum was obtained by varying different plating parameters like - molar ratio, current density range, and potential range. The observed co-deposited Molybdenum Atomic percentage variation in alloy was investigated for grain size, porosity in structure and surface roughness. The results revel that Molybdenum Atomic percentage in the Nickel–Molybdenum alloy has effect on porosity and surface roughness. It was also found that root mean square value of surface roughness was not only affected by the Molybdenum Atomic percentage but also by potential at relaxation time (TOFF) potential.

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40

Zhumasheva, Nazerke, Leyla Kudreeva, and Diana Kosybayeva. "Molybdenum oxide based sensors." Chemical Bulletin of Kazakh National University, no. 2 (June 30, 2021): 28–41. http://dx.doi.org/10.15328/cb1164.

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In this review article were considered the works of electrochemical sensors modified with molybdenum oxide. The work of sensors based on molybdenum oxide was systematized, a comparison table was developed, the sensors were classified according to the purpose of use. Methods of molybdenum oxide synthesis used to modify the working electrode in electrochemical sensors were considered. The various methods have been used to synthesize molybdenum oxide, such as a thermal, hydrothermal, electrochemical, electric spark, pulsed laser method, acid condensation, electrophoretic precipitation, pulse potential precipitation. The main parameters of the molybdenum oxide modified sensors, such as the detection limit, linear range, response time, sensitivity, and other parameters were compared. As a result of studies, it was found that molybdenum oxide is selected as a modifying material in electrochemical sensors due to the unique physicochemical properties of molybdenum oxide, in particular because of mechanical strength, electrical conductivity, electro catalytic activity, crystallinity. The features of electrochemical biosensors coated with molybdenum oxide were described for the detection of important compounds in specific samples. Sensors based on molybdenum oxide have been used for detection of glucose, dopamine, ethanol, ascorbic acid, troponin-1, norepinephrine, procalcitonin, L-lactate, bromate, chlorate, E110, tartrazine, hydrochlorothiazide, human epidermal growth factor-2, lithium,sodium,potassium. This paper provides general summarized information about current aspects of research works related to electrochemical sensors based on molybdenum oxide.

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41

Chen, Xiang Yang, Chun Yang Bu, Xin Zhe Lan, and Xin Rui Zhao. "Preparation of Superfine Molybdenum Powder by Reduction Process." Materials Science Forum 620-622 (April 2009): 723–26. http://dx.doi.org/10.4028/www.scientific.net/msf.620-622.723.

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The principle and process of producing molybdenum powder via reduction reaction of molybdenum trioxide at lower temperature in a N2-H2 system were researched. The effects of hydrogen concentration, temperature, and volatilization rate of molybdenum trioxide on particle size were analyzed. The experimental results showed that the optimal process parameters were 770°C-790°C in 60min when the hydrogen flow rate was 700mL/min. Particle size of superfine molybdenum powder was less than 4μm. The concentrations of hydrogen, temperature and volatilization rate of molybdenum trioxide have great effect on the particle size of superfine molybdenum powder.

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42

Li, Hongxia, Bingbing Shang, Guoqiang Wang, Kexing Song, Baohong Tian, and Fengzhang Ren. "Research on the technology of drying high moisture molybdenum concentrate powder with waste heat of roasting kiln." Journal of Physics: Conference Series 2690, no. 1 (January 1, 2024): 012006. http://dx.doi.org/10.1088/1742-6596/2690/1/012006.

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Abstract Molybdenum concentrate oxidation roasting is an important part of molybdenum metallurgy process. Aiming at the current situation of high energy consumption in the process of oxidation roasting and drying of molybdenum concentrate powder in China, based on the analysis of traditional mechanism and process of molybdenum concentrate roasting and heat transfer in rotary kiln, the heat is adjusted and a new rotary kiln drying system is designed to make 16-20% high-moisture molybdenum concentrate powder once dried. Drying each ton of molybdenum concentrate powder can save about 308125kJ of heat, equals toabout 14.38M gas or 10.53kg standard coal.

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Miroshnykov, I. "Current application directions for the weathering rind of molybdenum deposits of Ukraine." Collection of Research Papers of the National Mining University 75 (December 2023): 18–28. http://dx.doi.org/10.33271/crpnmu/75.018.

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Purpose. Justification of the new direction of using molybdenum ores from weathering rind of deposits of Ukraine. Research methodology. The research was carried out by general scientific and special research methods – theoretical (analysis, explanation, generalization, comparison), technical and economic evaluation. Research results. The conducted research made it possible to determine the main global approaches to the extraction and application of molybdenum in various areas of industry. The importance of the domestic industry's need for molybdenum-containing fertilizers is substantiated. The reasons why modern global methods for obtaining molybdenum-containing fertilizers are difficult have been revealed. It has been found that modern extraction of molybdenum occurs from native ores, and attempts to extract molybdenum from weathered ores are considered ineffective. The conducted studies indicate significant areas of weathering rinds in Ukraine, including on molybdenum ore occurrences. It is possible to use such weathering rinds as fertilizers directly, that is, bypassing the traditional production of concentrates. The reduction of molybdenum deficiency in Ukrainian arable soils can be achieved by using the weathering crust of molybdenum ore occurrences by soil exchange between enriched soils of ore deposit locations and depleted soils of seeded fields. The originality. For the first time, the regularity of correspondence between the mining term "significantly weathered molybdenum-containing ore" and the agricultural term "molybdenum-contaminated soil" was established. Significant volumes of such ore (soil) in Ukraine were confirmed, and the presence of signs of a promising molybdenum resource in it was also investigated. Practical value. The obtained data make it possible to partially solve the needs of Ukraine in molybdenum, which is currently not mined. The results of the research made it possible to substantiate the direction of the application of molybdenum weathering crust for the domestic agricultural industry, which increases the yield, quality of agricultural products, cultivated areas, income to the foreign currency budget due to the increase in the export of agricultural products, customs duties and taxes.

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44

Foteva, Vladimira, Joshua J. Fisher, Yixue Qiao, and Roger Smith. "Does the Micronutrient Molybdenum Have a Role in Gestational Complications and Placental Health?" Nutrients 15, no. 15 (July 27, 2023): 3348. http://dx.doi.org/10.3390/nu15153348.

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Molybdenum is an essential trace element for human health and survival, with molybdenum-containing enzymes catalysing multiple reactions in the metabolism of purines, aldehydes, and sulfur-containing amino acids. Recommended daily intakes vary globally, with molybdenum primarily sourced through the diet, and supplementation is not common. Although the benefits of molybdenum as an anti-diabetic and antioxidant inducer have been reported in the literature, there are conflicting data on the benefits of molybdenum for chronic diseases. Overexposure and deficiency can result in adverse health outcomes and mortality, although physiological doses remain largely unexplored in relation to human health. The lack of knowledge surrounding molybdenum intake and the role it plays in physiology is compounded during pregnancy. As pregnancy progresses, micronutrient demand increases, and diet is an established factor in programming gestational outcomes and maternal health. This review summarises the current literature concerning varied recommendations on molybdenum intake, the role of molybdenum and molybdoenzymes in physiology, and the contribution these play in gestational outcomes.

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45

Harutyunyan, L. R., L. S. Tangamyan, H. R. Petrosyan, R. K. Adamyan, H. H. Sargsyan, and R. S. Harutyunyan. "Disposal of sulfur anhydride of industrial gaseous wastes by modified natural zeolites." Voprosy Khimii i Khimicheskoi Tekhnologii, no. 5 (October 2023): 5–13. http://dx.doi.org/10.32434/0321-4095-2023-150-5-5-13.

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The effectiveness of sulfur anhydride sorption from roasted molybdenum concentrate gaseous wastes by modified natural zeolites has been studied. Clinoptilolite from Nor Koghb deposit (Noyemberyan, Armenia) has been used as natural zeolite. The modification of zeolite has been done by thermic, acidic and alkaline treatments. It has been established that both thermally and chemically modified zeolites of Nor Koghb deposit are effective sorbents for sorption of sulfur anhydride; moreover, it is determined that the alkaline modified samples of zeolite have the highest sorption ability. Sulfur anhydride has been produced by the three following sources: pure molybdenum disulfate, non-treated molybdenum concentrate from Zangezur Copper Molybdenum Combine (Armenia) and the same molybdenum concentrate after thermal treatment. The highest effectiveness of sulfur anhydride sorption is obtained when pure molybdenum disulfide is used as a sulfur anhydride source. This result is quite predictable because pure molybdenum disulfide practically all turns to sulfur anhydride while additives are present in molybdenum concentrate, which do not produce sulfur anhydride.

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46

Kudreeva, L. K., A. P. Kurbatov, D. Kh Kamysbayev, A. R. Kalyyeva, N. Zh Zhumasheva, M. B. Abilev, B. A. Serikbayev, and A. Dauletbay. "Electrochemical Separation of Molybdenum and Tungsten Using Aqueous-Organic Electrolytes." Eurasian Chemico-Technological Journal 22, no. 3 (September 30, 2020): 227. http://dx.doi.org/10.18321/ectj980.

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Molybdenum is one of the valuable metals for the industry; its special properties make it extremely urgent to study the process of separation of molybdenum from other impurities. The article considers the optimization of electrochemical separation of molybdenum from Mo-W system. The electrochemical dissolution of molybdenum and tungsten in solutions of LiCl and NH4NO3 in dimethylsulfoxide was studied using polarization curves and calculation of the efficiency of anodic dissolution of molybdenum in the presence of tungsten. The electrolyte with a composition of 0.5 M LiCl; 5.2 M dimethylsulfoxide; 32.2 M water was selected as an effective solution for the electrochemical separation of molybdenum in the potential range of 1.0‒2.2 V. Results obtained in this study can be used for the development of selective separation method in the molybdenum production.

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47

Chisholm, Malcolm H., Charles E. Hammond, and John C. Huffman. "Molybdenum hexadimethylamide." Journal of the Chemical Society, Chemical Communications, no. 19 (1987): 1423. http://dx.doi.org/10.1039/c39870001423.

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48

Hille, Russ. "Molybdenum enzymes." Essays in Biochemistry 34 (November 1, 1999): 125–37. http://dx.doi.org/10.1042/bse0340125.

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49

Morris, Michael J. "Molybdenum 1995." Coordination Chemistry Reviews 164 (September 1997): 289–344. http://dx.doi.org/10.1016/s0010-8545(97)00033-7.

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MORRIS, M. "Molybdenum 1996." Coordination Chemistry Reviews 172, no. 1 (May 1998): 181–245. http://dx.doi.org/10.1016/s0010-8545(98)00093-9.

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Journal articles on the topic 'Molybdenum'

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