Preparation and Characterization of Isostructural Na2MoO4 and Na2WO4 and a Study of the Composition of Their Mixed System

Ubaldini, Alberto; Cicconi, Flavio; Rizzo, Antonietta; Salvi, Stefano; Cuzzola, Vincenzo; Gennerini, Francesco; Bruni, Stefania; Marghella, Giuseppe; Gessi, Alessandro; Falsini, Naomi

doi:10.3390/molecules28186602

Cited by 4 publications

(2 citation statements)

References 45 publications

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“…Silver molybdate crystalizes in different polymorphs, among which is the meta-stable tetragonal α-phase [9,16]. Solid-state reactions lead to the almost exclusive formation of this phase.…”

Section: Resultsmentioning

confidence: 99%

Characterization and Formation Mechanism of Ag2MoO4 Crystals via Precipitation Method: Influence of Experimental Parameters and Crystal Morphology

Calistri,

Gessi,

Marghella

et al. 2024

Crystals

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Ag2MoO4 crystals were prepared by a precipitation method by mixing parent solutions of silver nitrate and sodium molybdate. The effects of experimental parameters such as temperature, concentration, and pH were studied. The samples were found to be crystalline, pure, and monophasic in all cases, except in the case of very low pH. The precipitation leads to the formation of the cubic phase β and no secondary phase is present within the limits of detection of XRD and Raman spectroscopy. However, in some cases, at high temperature and high pH, silver oxide nanoparticles form on the surfaces of the crystals, which create a fluorescence background in the Raman spectra, which is otherwise absent. Analyses with the electron microscope have highlighted that the most common crystalline shape is octahedral, which is the most prevalent at low temperatures and pH around 7, but others are also possible, in particular at high temperatures. No growth occurs after precipitation, so crystals with different appearances form at the same time.

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Section: Resultsmentioning

confidence: 99%

Characterization and Formation Mechanism of Ag2MoO4 Crystals via Precipitation Method: Influence of Experimental Parameters and Crystal Morphology

Calistri,

Gessi,

Marghella

et al. 2024

Crystals

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“…Both thorium and tungsten are obtained from ores by established processes such as hydrometallurgical treatment [ 17 , 18 , 19 ], separation [ 20 , 21 , 22 , 23 , 24 ], and treatment of alloys [ 25 ]. Moreover, tungsten has been the focus of process engineers for its recovery from various residues through electrolytic processes and acid or basic solubilization processes [ 26 , 27 , 28 , 29 , 30 ]. On the other hand, thorium has been the focus of researchers in the field of membranes for concentration, separation or purification, especially when it comes from ores in which uranium or rare earths can also be found [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ] ( Table 1 ).…”

Section: Introductionmentioning

confidence: 99%

Simultaneously Recovery of Thorium and Tungsten through Hybrid Electrolysis–Nanofiltration Processes

Man,

Albu,

Nechifor

et al. 2024

Toxics

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The recovery and recycling of metals that generate toxic ions in the environment is of particular importance, especially when these are tungsten and, in particular, thorium. The radioactive element thorium has unexpectedly accessible domestic applications (filaments of light bulbs and electronic tubes, welding electrodes, and working alloys containing aluminum and magnesium), which lead to its appearance in electrical and electronic waste from municipal waste management platforms. The current paper proposes the simultaneous recovery of waste containing tungsten and thorium from welding electrodes. Simultaneous recovery is achieved by applying a hybrid membrane electrolysis technology coupled with nanofiltration. An electrolysis cell with sulphonated polyether–ether–ketone membranes (sPEEK) and a nanofiltration module with chitosan–polypropylene membranes (C–PHF–M) are used to carry out the hybrid process. The analysis of welding electrodes led to a composition of W (tungsten) 89.4%; Th 7.1%; O2 2.5%; and Al 1.1%. Thus, the parameters of the electrolysis process were chosen according to the speciation of the three metals suggested by the superimposed Pourbaix diagrams. At a constant potential of 20.0 V and an electrolysis current of 1.0 A, the pH is varied and the possible composition of the solution in the anodic workspace is analyzed. Favorable conditions for both electrolysis and nanofiltration were obtained at pH from 6 to 9, when the soluble tungstate ion, the aluminum hydroxide, and solid thorium dioxide were formed. Through the first nanofiltration, the tungstate ion is obtained in the permeate, and thorium dioxide and aluminum hydroxide in the concentrate. By adding a pH 13 solution over the two precipitates, the aluminum is solubilized as sodium aluminate, which will be found after the second nanofiltration in the permeate, with the thorium dioxide remaining integrally (within an error of ±0.1 ppm) on the C–PHF–M membrane.

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Thiamine-modified octamolybdate catalyzes solvent-free stereoselective olefin epoxidation with TBHP

Rezaeifard,

Jafarpour,

Rostaminasab

et al. 2024

Molecular Catalysis

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Preparation and Characterization of Isostructural Na2MoO4 and Na2WO4 and a Study of the Composition of Their Mixed System

Cited by 4 publications

References 45 publications

Characterization and Formation Mechanism of Ag2MoO4 Crystals via Precipitation Method: Influence of Experimental Parameters and Crystal Morphology

Characterization and Formation Mechanism of Ag2MoO4 Crystals via Precipitation Method: Influence of Experimental Parameters and Crystal Morphology

Simultaneously Recovery of Thorium and Tungsten through Hybrid Electrolysis–Nanofiltration Processes

Thiamine-modified octamolybdate catalyzes solvent-free stereoselective olefin epoxidation with TBHP

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