Détermination de la pression de vapeur de HgCl2 par la méthode d'effusion de Knudsen

Bernard, Laurent; Awitor, Komla Oscar; Badaud, J.P.; Bonnin, Olivier; Coupat, B.; Fournier, Julien; Verdier, P.

doi:10.1051/jp3:1997124

Cited by 8 publications

(4 citation statements)

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“…It is instructive to compare this case against an experiment where the exchange reaction was studied between gaseous HgBr 2 and solid HgCl 2 deposited on the surface of a frosted borosilicate (Pyrex) tube, similar as in our recently reported uptake experiments . Not only HgCl 2 is more volatile than HgBr 2 , − but also its binding with the frosted tube is weaker than with the membrane. Hence, a significant amount of HgCl 2 was continuously desorbed into the helium flow and carried into ID-CIMS, producing a HgCl 2 F – signal approximately 100 times stronger than the signal of HgBr 2 F – (Figure S2).…”

Section: Resultsmentioning

confidence: 67%

Exchange Reactions Alter Molecular Speciation of Gaseous Oxidized Mercury

Mao

Khalizov

2021

ACS Earth Space Chem.

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The knowledge of speciation of gaseous oxidized mercury (GOM) is crucial for understanding the atmospheric mercury chemistry and global cycle. Because of the low atmospheric abundance of GOM, its chemical analysis requires preconcentration and often involves the use of collection substrates, such as KCl, various adsorbents, or membranes. GOM molecules adsorbed on substrates can exchange ligands with the substrate material, each other, or other coadsorbed atmospheric chemicals, altering the composition of GOM and ultimately leading to speciation biases. Here, we investigated exchange reactions involving GOM surrogates HgBr2, HgCl2, and Hg(NO3)2 and different forms of Cl– (as KCl, NH4Cl, and HCl). The reactions were studied in aqueous solutions and on surfaces, and the products were analyzed in the gas phase (by ion drift–chemical ionization mass spectrometry), in solution (by electrospray ionization–mass spectrometry), and on surface (by Raman microscopy). In all cases, we observed a rapid formation of exchange products HgBrCl and HgCl2, which readily volatilized not only upon heating, but also often at room temperature, depending on substrate adsorptivity. We propose that a similar exchange may occur both on atmospheric aerosols and during analysis, where the original GOM species (e.g., BrHgONO and BrHgOOH) would react on surfaces/particles with each other and atmospherically abundant trace species to form other mercury(II) chemicals. For example, a readily volatilizable HgCl2 can be produced through the exchange with chloride.

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Section: Resultsmentioning

confidence: 67%

Exchange Reactions Alter Molecular Speciation of Gaseous Oxidized Mercury

Mao

Khalizov

2021

ACS Earth Space Chem.

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“…As no scale spallation could be detected by microscopic examinations, these mass losses were the result of oxide evaporation, as already observed for stainless steels [1][2][3][4]. Using the Knudsen effusion model [5] and FactSage [6] evaluation of the partial pressures of chromium trioxide and chromium (IV) oxohydroxides, mass losses were calculated to be 56 µg.cm -2 (304 and 316L), 43 µg.cm -2 (441) and 2 µg.cm -2 (430), in correct agreement with the differences between experimental mass and thickness values.…”

Section: High Temperature Corrosion and Protection Of Materialsmentioning

confidence: 67%

Short Term Oxidation of Stainless Steels during Final Annealing

Gonzales¹,

Combarmond

Tran

et al. 2008

MSF

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Two ferritic AISI 430 and AISI 441 and two austenitic AISI 304 and AISI 316L stainless steels were submitted to short term oxidation in a complex atmosphere 3% O2, 16% H2O, 8% CO2, 73% N2 to simulate phenomena occurring during the rapid furnace annealing taking place after the final cold rolling. This thermal sequence is devoted to metallurgical aims but generates undesirable oxides which have to be further pickled. Temperature of the furnace was set to the values used in industrial practice: 900°C for 430, 1060°C for 441 and 1120°C for both austenitics. Six different oxidation durations were used between 30 and 300 s. For the shortest times, sample temperature was not constant and heating rate depended on sample thickness. Oxide thickness measured by GDOS was shown to increase monotonically for all grades whereas mass change measurements exhibited initial mass losses for the austenitic grades. XRD and Raman spectroscopy were used for phase characterisation and confirmed the increase of the ratio chromia/haematite with increasing annealing time. Enrichment of manganese (MnCr2O4), silicon (SiO2) and boron (B-containing oxide) at the external (Mn) and internal (Si, B) interfaces was observed on the GDOS profiles (boron for austenitic grades only). Manganese spinel was responsible for blocking chromium (VI) volatilisation after a certain time, and interface oxides for hindering chromium transfer from the steel to the oxide scale. Ferritic grades behaved the same, except that no boron enrichment was detected. Besides, stabilised 441 exhibited Ti and Nb enrichments as oxides at both internal and external interfaces. External TiO2-NbO2 solid solution was assumed to be hardly dissolved in acidic pickling baths. All these results were consistent with the different pickling behaviours of the materials.

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“…Additionally, the fate of mercury captured on the adsorbent was expected to be in complex form rather than as mercury(II) chloride that can leach under Reaction Chemistry & Engineering Paper high pressure or accelerated conditions. 33,63,64 The possible mercury reaction mechanism is not conclusive enough to be reported without further in situ analytical work and needs to be probed for both copper and mercury centres. We anticipate that mercury fixation under these wet-gas conditions was via the formation of more stable mercury complexes on the silica support rather than in a molecular state of HgCl 2 , which was reported to be formed under drygas conditions.…”

Section: Reaction Chemistry and Engineeringmentioning

confidence: 99%