Hydrated-layer formation during dissolution of complex silicate glasses and minerals

Petit, Jean‐Claude; Mea, G. Della; Dran, J. C.; Magonthier, Marie-Claude; Mandò, P.A.; Paccagnella, A.

doi:10.1016/0016-7037(90)90263-k

Cited by 112 publications

(70 citation statements)

References 37 publications

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“…The Na contents of the glass from those three ash samples are almost the same and much smaller than that of typical rhyolite. Petit et al (1990) showed that hydration of rhyolitic glass is controlled by hydrogen/alkali ion exchange, with Na removal from rhyolitic glass occurring concomitantly with hydration and ion-exchange with K in the hydrated layers. Hydration and ion-exchange may occur without formation of secondary minerals (Jezak and Noble 1978); That is, those relations imply that the aluminosilicate framework of the glass may remain intact, with hydration and loss of alkalis occurring only by diffusion through interframework voids.…”

Section: Glass Alterationmentioning

confidence: 99%

Relation Between Interlayer Composition of Authigenic Smectite, Mineral Assemblages, I/S Reaction Rate and Fluid Composition in Silicic Ash of the Nankai Trough

Masuda

1996

Clays and clay miner.

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Abstract--The compositions, fabrics and structures of authigenic minerals that formed recently from silicic volcanic ash layers from a 1300-meter sediment column obtained at ODP Site 808 of the Nankai Trough were studied using XRD, STEM, AEM and SEM. Smectite and zeolites were first detected as alteration products of volcanic glass with increasing depth, as follows: smectite at 200 m below seafloor (mbsf) (20 ~ clinoptilolite at 640 mbsf (60 ~ and analcime at 810 mbsf (75 ~ A primitive clay precursor to smectite was observed as a direct alteration product of glass at 366 mbsf (approximately 30 ~ High defect smectite with lattice fringe spacings of 12 to 17 A and having a cellular texture filling pore space between altering glass shards occurs at 630 mbsf. Packets of smectite become larger and less disordered with increasing depth and temperature. The smectite that forms as a direct alteration product of volcanic glass has K as the dominant interlayer cation.With increasing depth, smectite becomes depleted in K as the proportion of clinoptilolite increases, and then becomes depleted in Na as the proportion of analcime increases. The composition of the exchangeable interlayer of smectite appears to be controlled by the formation first of K-rich clinoptilolite and then Na-rich analcime, via the pore fluid, giving rise at depth to Ca-rich smectite. Smectite reacted to form illite in the interbedded shales but not in the bentonites. Paucity of K in smectite and pore fluids, due to formation of clinoptilolite under closed system conditions, is believed to have inhibited the reaction relative to shales.

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Section: Glass Alterationmentioning

confidence: 99%

Relation Between Interlayer Composition of Authigenic Smectite, Mineral Assemblages, I/S Reaction Rate and Fluid Composition in Silicic Ash of the Nankai Trough

Masuda

1996

Clays and clay miner.

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“…Analytical electron microscopic (AEM) investigations of the surface layers of reacted nuclear waste glasses [7,12] indicate that they quickly precipitate in surface layers composed of such phases as di-and tri-octahedral smectites, serpentines, and transition metal oxides and silicates. Commonly, the initial precipitates are amorphous hydrosilicates that with time segregate into distinct crystalline phases.…”

Section: Reaction Mechanismsmentioning

confidence: 99%

“…Therefore, higher temperatures will increase the rate of water diffusion faster than the rate of surface reaction. This shift will favor the formation of surface hydration layers in high temperature dissolution tests [12].…”

Section: Effect Of Glass Compositionmentioning

confidence: 99%

Overview of Chemical Modeling of Nuclear Waste Glass Dissolution

Bourcier

1990

MRS Proc.

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Glass dissolution takes place through metal leaching and hydration of the glass surface accompanied by development of alteration layers of varying crystallinity. The reaction which controls the long-term glass dissolution rate appears to be surface layer dissolution. This reaction is reversible because the buildup of dissolved species in solution slows the dissolution rate due to a decreased dissolution affinity. Glass dissolution rates are therefore highly dependent on silica concentrations in solution because silica is the major component of the alteration layer.Chemical modeling of glass dissolution using reaction path computer codes has successfully been applied to short term experimental tests and used to predict long-term repository performance. Current problems and limitations of the models include a poorly defined long-term glass dissolution mechanism, the use of model parameters determined from the same experiments that the model is used to predict, and the lack of sufficient validation of key assumptions in the modeling approach. Work is in progress that addresses these issues.

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“…However, information drawn from natural samples, is often limited due to slow alteration rates and uncertainties concerning the natural conditions during alteration (Magonthier 1992). In addition, the extrapolation of short-term hydrothermal weathering experiments require kinetic models to predict long-term weathering processes (Petit et al 1990;Michaux et al 1992).…”

Section: Introductionmentioning

confidence: 99%

Mechanism and Conditions of Clay Formation During Natural Weathering of MSWI Bottom Ash

Zevenbergen¹

1996

Clays and clay miner.

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Abstract--Municipal solid waste incinerator (MSWI) bottom ash is the slag-like material produced by the incineration of municipal waste and is predominantly composed of glassy constituents, which include inherited manufactured glasses and glasses formed during incineration. Previous results indicate evidence of neoformation of well-ordered clay (illite) from glasses in MSWI bottom ash after 12 y of natural weathering. We investigated the mechanism and conditions of clay formation from glasses during natural weathering using transmission electron microscopy (TEM), experimental leaching experiments and ammonium oxalate extractions. It was concluded that the high surface area and initially high "active" A1 and associated Si content predispose the ash to form clay minerals on a relatively short time scale. This work provides evidence that the composition of secondary amorphous aluminosilicate and thus, the type of clay mineral which may form, is determined by the pH of the pore solution rather than by the glass composition. Presumably alternate wetting and drying of the ash during disposal greatly accelerates the formation of well-ordered clays.

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Hydrated-layer formation during dissolution of complex silicate glasses and minerals

Cited by 112 publications

References 37 publications

Relation Between Interlayer Composition of Authigenic Smectite, Mineral Assemblages, I/S Reaction Rate and Fluid Composition in Silicic Ash of the Nankai Trough

Relation Between Interlayer Composition of Authigenic Smectite, Mineral Assemblages, I/S Reaction Rate and Fluid Composition in Silicic Ash of the Nankai Trough

Overview of Chemical Modeling of Nuclear Waste Glass Dissolution

Mechanism and Conditions of Clay Formation During Natural Weathering of MSWI Bottom Ash

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