Surface Chemistry and Durability of Borosilicate Glass

ABSTRACTPreliminary results show that glass durability is dependent on reactions occurring at the glass-solution interface. CSG glass (18.2 wt. % Na2O,5.97 wt. % CaO, 11.68 wt. % Al2O3, 8.43 wt. % B2O3, and 55.73 wt. % SiO2) dissolution and net surface H+ and OH- adsorption are minimal at near neutral pH. In the acid and alkaline pH regions, CSG glass dissolution rates are proportional to 2 to , respectively. In contrast, silica gel dissolution and net H+ and OH" adsorption are minimal and independent of pH in acid to neutral solutions. In the alkaline pH region, silica gel dissolution is proportional 0.9 to . Although Na adsorption is significant for CSG glass and silica gel in the alkaline pH regions, it is not clear if it enhances dissolution, or is an artifact of depolymerization of the framework bonds.

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A Kinetic Model for Borosilicate Glass Dissolution Based on the Dissolution Affinity of a Surface Alteration Layer

MRS Proceedings ◽

10.1557/proc-176-209 ◽

1989 ◽

Vol 176 ◽

Cited By ~ 60

Author(s):

William L. Bourcier ◽

Dennis W. Peiffer ◽

Kevin G. Knauss ◽

Kevin D. McKeegan ◽

David K. Smith

Keyword(s):

Kinetic Model ◽

Dissolution Rate ◽

Borosilicate Glass ◽

Geochemical Modeling ◽

Secondary Phases ◽

Dissolution Rates ◽

Ion Concentrations ◽

Glass Dissolution ◽

Gel Layer ◽

Amorphous Surface

ABSTRACTA kinetic model for the dissolution of borosilicate glass, incorporated into the EQ3/6 geochemical modeling code, is used to predict the dissolution rate of a nuclear waste glass. In the model, the glass dissolution rate is controlled by the rate of dissolution of an alkalidepleted amorphous surface (gel) layer. Assuming that the gel layer dissolution affinity controls glass dissolution rates is similar to the silica saturation concept of Grambow [1] except that our model predicts that all components concentrated in the surface layer, not just silica, affect glass dissolution rates. The good agreement between predicted and observed elemental dissolution rates suggests that the dissolution rate of the gel layer limits the overall rate of glass dissolution. The model predicts that the long-term rate of glass dissolution will depend mainly on ion concentrations in solution, and therefore on the secondary phases which precipitate and control ion concentrations.

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Photodegradation of fluoroquinolones in aqueous solution under light conditions relevant to surface waters, toxicity assessment of photoproduct mixtures.

10.21203/rs.3.rs-274285/v1 ◽

2021 ◽

Author(s):

Sarka Klementova ◽

Martina Poncarová ◽

Helena Langhansová ◽

Jaroslava Lieskovská ◽

David Kahoun ◽

...

Keyword(s):

Aqueous Solution ◽

Antibacterial Activity ◽

Surface Waters ◽

Ph Value ◽

Reaction System ◽

Photochemical Degradation ◽

Alkaline Ph ◽

Light Conditions ◽

E Coli ◽

Neutral Ph

Abstract Photochemical degradation of fluoroquinolones ciprofloxacin, enrofloxacin and norfloxacin in aqueous solution under light conditions relevant to surface waters at neutral and alkaline pH was found to proceed readily with half-lives between 0.9 and 2.7 min. The products of photochemical degradation identified by HPLC-MS included defluorinated, hydroxylated, and decarboxylated structures as well as structures with opened cyclic structures. For all of the studied substances, the reaction pathways were influenced significantly by the pH of the reaction system, with more products formed at alkaline pH than at neutral pH: the ratios of products in neutral and alkaline pH were 16/26, 9/19, 15/23 for ciprofloxacin, enrofloxacin, and norfloxacin, respectively. The structures of photoproducts and pathways of photochemical degradation are proposed. The antibacterial activities of photoproduct mixtures tested on E. coli and S. epidermidis were significantly higher in comparison to parental antibiotics in the case of both ciprofloxacin and enrofloxacin with p-values less than 0.0001 in most cases. The effect of the photoproducts was shown to be dependent on the pH value of the original antibiotic solutions before photodegradation: for ciprofloxacin, antibacterial activity against E. coli was more notably pronounced with regard to neutral pH photoproducts, while a less significant, or in one case not significant, effect of pH was observed against S. epidermidis ; for norfloxacin, antibacterial activity against both E. coli and S. epidermidis were especially high with regard to alkaline pH photoproducts

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Surface Chemistry of Mesoporous Materials: Effect of Nanopore Confinement

MRS Proceedings ◽

10.1557/proc-751-z3.40 ◽

2002 ◽

Vol 751 ◽

Author(s):

Yifeng Wang ◽

Charles Bryan ◽

Huifang Xu ◽

Huizhen Gao

Keyword(s):

Surface Chemistry ◽

Surface Acidity ◽

Scale Space ◽

Acid Base ◽

Acidity Constants ◽

Solution Interface ◽

Ion Sorption ◽

Alumina Particles ◽

The Difference ◽

Nanopore Confinement

AbstractAcid-base titration and metal sorption experiments were performed on both mesoporous alumina and alumina particles under various ionic strengths. It has been demonstrated that surface chemistry and ion sorption within nanopores can be significantly modified by a nano-scale space confinement. As the pore size is reduced to a few nanometers, the difference between surface acidity constants (ΔpK = pK2 – pK1) decreases, giving rise to a higher surface charge density on a nanopore surface than that on an unconfined solid-solution interface. The change in surface acidity constants results in a shift of ion sorption edges and enhances ion sorption on that nanopore surfaces.

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The initial dissolution rates of simulated UK Magnox–ThORP blend nuclear waste glass as a function of pH, temperature and waste loading

Mineralogical Magazine ◽

10.1180/minmag.2015.079.6.28 ◽

2015 ◽

Vol 79 (6) ◽

pp. 1529-1542 ◽

Cited By ~ 14

Author(s):

N. Cassingham ◽

C.L. Corkhill ◽

D.J. Backhouse ◽

R.J. Hand ◽

J.V. Ryan ◽

...

Keyword(s):

Dissolution Kinetics ◽

Intrinsic Rate ◽

Waste Glass ◽

High Level Waste ◽

Dissolution Mechanism ◽

Dissolution Rates ◽

Forward Rates ◽

Glass Dissolution ◽

High Level ◽

Kinetics Of

AbstractThe first comprehensive assessment of the dissolution kinetics of simulant Magnox–ThORP blended UK high-level waste glass, obtained by performing a range of single-pass flow-through experiments, is reported here. Inherent forward rates of glass dissolution were determined over a temperature range of 23 to 70°C and an alkaline pH range of 8.0 to 12.0. Linear regression techniques were applied to the TST kinetic rate law to obtain fundamental parameters necessary to model the dissolution kinetics of UK high-level waste glass (the activation energy (Ea), pH power law coefficient (η) and the intrinsic rate constant (k0)), which is of importance to the post-closure safety case for the geological disposal of vitreous products. The activation energies based on B release ranged from 55 ± 3 to 83 ± 9 kJ mol–1, indicating that Magnox–THORP blend glass dissolution has a surface-controlled mechanism, similar to that of other high-level waste simulant glass compositions such as the French SON68 and LAW in the US. Forward dissolution rates, based on Si, B and Na release, suggested that the dissolution mechanism under dilute conditions, and pH and temperature ranges of this study, was not sensitive to composition as defined by HLW-incorporation rate.

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The effect of aqueous sulphate on basaltic glass dissolution rates

Mineralogical Magazine ◽

10.1180/minmag.2008.072.1.39 ◽

2008 ◽

Vol 72 (1) ◽

pp. 39-41 ◽

Cited By ~ 11

Author(s):

T. K. Flaathen ◽

E. H. Oelkers ◽

S. Gislason

Keyword(s):

Steady State ◽

Rate Equation ◽

Rate Increase ◽

Basaltic Glass ◽

Mixed Flow ◽

Dissolution Rates ◽

Flow Reactors ◽

Glass Dissolution ◽

Sulphate Concentration

AbstractSteady-state dissolution rates of basaltic glass were measured in mixed-flow reactors at 50ºC at pH 3 and 4 as a function of aqueous sulphate concentration. Dissolution rates in the presence of 0.1 moles/kg SO42- were found to be ~3 times greater than those in corresponding SO42- free solutions. This rate increase is found to be approximately consistent with that calculated using a rate equation previously proposed by Gislason and Oelkers (2003). These results suggest that the addition of sulphate to injected CO2 may facilitate CO2 sequestration in basalts by accelerating basaltic glass dissolution rates thus more rapidly releasing aqueous Ca and Mg to solution.

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pH of Medicated Syrups–Does It Really Matter? – An in-vitro Study: Part-II

Journal of Clinical Pediatric Dentistry ◽

10.17796/jcpd.33.2.q5280t3744827v0h ◽

2008 ◽

Vol 33 (2) ◽

pp. 137-142 ◽

Cited By ~ 2

Author(s):

KL Girish Babu ◽

Kavita Rai ◽

Amitha Hegde

Keyword(s):

Atomic Absorption ◽

In Vitro Study ◽

Vitro Study ◽

Atomic Absorption Spectrometer ◽

Alkaline Ph ◽

Time Intervals ◽

Neutral Ph ◽

Absorption Spectrometer ◽

Dissolution Potential

The aim of the present in vitro study was to quantify the endogenous erosive potential of the various pediatric liquid medicaments by measuring the calcium dissolution of primary enamel after immersing it for different time intervals (1min, 10 min and 8 hours) using atomic absorption spectrometer (AAS). The eight commonly used pediatric liquid medicaments which were selected had definitive endogenous calcium dissolution potential. All the medicaments showed calcium dissolution of primary enamel at alkaline pH and near neutral pH. The calcium dissolution potential of pediatric liquid medicaments when compared with their respective pH showed no statistically significant correlation. In conclusion, there was evidence of calcium dissolution from all the pediatric liquid medicaments.

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Changing the shape of hair with keratin peptides

RSC Advances ◽

10.1039/c7ra10461h ◽

2017 ◽

Vol 7 (81) ◽

pp. 51581-51592 ◽

Cited By ~ 16

Author(s):

C. F. Cruz ◽

M. Martins ◽

J. Egipto ◽

H. Osório ◽

A. Ribeiro ◽

...

Keyword(s):

Reducing Agents ◽

Alkaline Ph ◽

Neutral Ph ◽

Disulphide Bonds

Here we propose a solution which will replace harsh reducing agents at alkaline pH by peptide formulations acting at neutral pH to change hair shape through the re-conformation of disulphide bonds.

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The Long-Term Dissolution Behaviour of the Pamela Borosilicate Glass SM527 - Application of SA/V as Accelerating Parameter

MRS Proceedings ◽

10.1557/proc-257-49 ◽

1991 ◽

Vol 257 ◽

Cited By ~ 8

Author(s):

K. Lemmens ◽

P. Van Iseghem

Keyword(s):

Borosilicate Glass ◽

Water Mixture ◽

Boom Clay ◽

Glass Dissolution ◽

Dissolution Behaviour ◽

Powdered Glass ◽

Clay Slurry ◽

Term Data ◽

Solution Volume

ABSTRACTThe Al2O3 rich borosilicate glass SM527 was submitted to corrosion tests with glass surface area to solution volume ratios ranging from 10 to 10000 m-1. This latter condition would correspond with a 1000 fold acceleration relative to the reference MCCI condition. Powdered glass was used to reach SANV ratios of 500 m-1 and more. The leaching solutions were either distilled water or referred to Boom clay disposal conditions. The results based on the boron concentration in solution revealed a relatively linear dependence on SA/V.t0.5 in the pure solutions, on the longer term (DW and clay water). Diffusion is suggested to be the process governing the glass dissolution, although other processes should not be excluded. In a clay / clay water mixture (slurry), long term dissolution seems to be limited by saturation. Short term data for boron are largest in the clay slurry, but with time the boron concentrations converge to similar values in the three media considered. The use of SA/V as an accelerating factor is promising, but certainly requires additional research.

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