Heats of immersion in the thorium oxide-water system. IV. Variation of the net differential heat of adsorption with specific surface area

Holmes, H.F.; Fuller, E.L.; Secoy, C. H.

doi:10.1021/j100852a036

Cited by 20 publications

(11 citation statements)

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“…Surface hydroxyl groups are probably not removed at outgassing temperatures below 250°C, even under vacuum conditions of 10 À7 kPa [38,56]. Anecdotal evidence indicates temperatures of at least 800-1000°C are necessary to remove all chemisorbed water from the ThO 2 surface [57][58][59]. Outgassing at temperatures as high as 1300°C may be necessary to reduce the surface hydroxyl content of thorium oxide below levels detectable by infrared spectroscopy [36,38].…”

Section: Drying Characteristicsmentioning

confidence: 99%

“…Large heats of immersion, 29-92 kJ mol À1 at 25°C, and their apparent dependence on outgassing temperature are attributed to chemisorbed water [36,38,57]. Theoretically, chemisorbed water is dissociatively adsorbed to form hydroxyls at the oxide surface.…”

Section: Rehydrationmentioning

confidence: 99%

“…Multiple adsorption/desorption cycles are required to achieve an equilibrium isotherm. The cycling may facilitate progressive development of a multilayer structure with stronger (more optimal) hydrogen bonding [49,50,57,60,61]. Analysis of the heat of immersion of thorium oxide in water indicates three hydration reactions with immediate, slow, and very slow kinetics, respectively.…”

Section: Rehydrationmentioning

confidence: 99%

“…Analysis of the heat of immersion of thorium oxide in water indicates three hydration reactions with immediate, slow, and very slow kinetics, respectively. Immediate hydration is assumed to correspond to the formation of chemisorbed species [57].…”

Section: Rehydrationmentioning

confidence: 99%

“…For relative humidities greater than 70%, pellet moisture adsorption data diverge from this model, but the equation offers an independent estimate from the adsorption theory developed at ORNL [31,50,57,62].…”

Section: Rehydrationmentioning

confidence: 99%

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Drying characteristics of thorium fuel corrosion products

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Section: Rehydrationmentioning

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Drying characteristics of thorium fuel corrosion products

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2004

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Heats of Immersion of Hydroxyapatities in Water

Rootare

Craig

1974

Analytical Calorimetry

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Heats of immersion have been reported for many polar solids of metal oxides and silicates both in polar and nonpolar liquids. These heats have been determined as a function of outgassing temperatures, specific surface areas, and particle size. Usually they are made on the "bare" sample only. However, with most of the hydrophilic metal oxide surfaces, it is not always known whether the surface was "bare" (i.e. completely dehydroxylated) or had some residual hydroxyl groups still on the surface. How "bare" the surface was, would depend greatly upon the outgassing temperature and pressure at which the sample was prepared. Although the heats measured were relatively insensitive to these factors for a nonpolar liquid such as hexane on silica, titanium dioxide, or alumina 1 , for a polar molecule such as water on these solids, large and complex changes have been observed 2 • Wade and Hackerman, et al. measured heats of immersion for water on Ti02 3 , Si02 4 • 5 , and on Al203 6 • 7 as a function of the outgassing tem~erature and specific surface area. Whalen 8 and Kiselev, et al. • 10 measured heats of immersion of different silica gel preparations and quartz. Holmes, Fuller and Secoy 11 -14 did an extensive study on the theria-water system, investigating the effect of outgassing temperature on heat of immersion and relating it to surface hydration of Th02, Morimoto, et al. 15 -18 , who investigated the ZnO-water system quite extensively by the water vapor adsorption method, have also conducted calorimetric measurements of heats of immersion on several metal oxides. The effect of outgassing temperature on loss of surface water and the heats of immersion were measured on both aand y-alumina 15 , Zn0 16 , Ti02 17 , and a-Fe203 18 The heats of immersion were related to change in surface area on heating and to decrease in water content with

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Heats of adsorption of carbon monoxide on bone mineral and on thorium oxide by gas-solid chromatography

Nash

Beebe

1969

Journal of Colloid and Interface Science

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Heats of immersion in the thorium oxide-water system. IV. Variation of the net differential heat of adsorption with specific surface area

Cited by 20 publications

References 4 publications

Drying characteristics of thorium fuel corrosion products

Drying characteristics of thorium fuel corrosion products

Heats of Immersion of Hydroxyapatities in Water

Heats of adsorption of carbon monoxide on bone mineral and on thorium oxide by gas-solid chromatography

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