Cationic Corrosion Inhibitors for Alkaliborosilicate Glass

1991 ◽  
Vol 257 ◽  
Author(s):  
H.U. Zwicky ◽  
TH. Graber ◽  
R. Grauer ◽  
R. Restani
Keyword(s):  
Dissolution Rate ◽  
Corrosion Inhibitors ◽  
Pure Water ◽  
Reaction Rates ◽  
Alkaline Solutions ◽  
Lead Silicate ◽  
Borosilicate Glasses ◽  
Glass Dissolution ◽  
Inhibiting Effect ◽  
Solid Phases

ABSTRACTThe dissolution behaviour of two alkali borosilicate glasses has been investigated at 90°C in the presence of potential corrosion inhibitors. The added materials were selected on the basis of surface chemistry considerations: Since the dissolution rate of silicate solid phases in alkaline solutions increases with growing negative surface charge, it should be expected that sorbing cations reduce the reaction rates. Due to the formation of insoluble hydroxides and silicates and to the dominance of neutral or negatively charged hydroxo complexes in the pH range of interest, the selection of potential inhibitors is very restricted.The precipitated hydroxides of Al, Zn, Cd and Pb were chosen as the solid phases. Compared with the experiments in pure water, glass dissolution is enhanced in presence of Al(OH)3 and Zn(OH)2. The concentration of the aqua ions is too low for an inhibiting effect. Sorption of silicic acid on the hydroxide accelerates the glass dissolution. Addition of PbO had a strong inhibiting effect in a 28 days experiment. At longer times an insoluble lead silicate is formed and thereby the glass dissolution rate is increased. Cd on the other hand is still effective as an inhibitor after 365 days.Based on the present results, the possibility of using glass corrosion inhibitors in a repository is considered not to be worthwhile.

Dissolution Kinetics of a Simple Analogue Nuclear Waste Glass as a Function of Ph, Time and Temperature

1989 ◽  
Vol 176 ◽  
Author(s):  
Kevin G. Knauss ◽  
William L. Bourcier ◽  
Kevin D. McKeegan ◽  
Celia I. Merzbacher ◽  
Son N. Nguyen ◽  
...  
Keyword(s):  
Dissolution Rate ◽  
Rate Constant ◽  
Rate Constants ◽  
Dissolution Kinetics ◽  
State Theory ◽  
Alkaline Solutions ◽  
Glass Dissolution ◽  
Constant Ph ◽  
Transport Control ◽  
Dissolution Rate Constants

ABSTRACTWe have measured the dissolution rate of a simple five-component borosilicate glass (Na2O, CaO, Al2O3, B2O3, SiO2) using a flow-through system. The experiments were designed to measure the dissolution rate constant over the interval pH 1 through pH 13 at 3 temperatures (25°, 50° and 70°C). Dilute buffers were used to maintain a constant pH. Analyses of solutions and solid surfaces provided information that is used to develop a kinetic model for glass dissolution.Under all conditions we eventually observed linear dissolution kinetics. In strongly acidic solutions (pH 1 to pH 3) all components but Si were released in their stoichiometric proportions and a thick, Si-rich gel was formed. In mildly acidic to neutral solutions the gel was thinner and was both Si- and Al-rich, while the other components were released to solution in stoichiometric proportions. In mildly to strongly alkaline solutions all components were released to solution in stoichiometric proportions. By varying the flow rate at each pH we demonstrated a lack of transport control of the dissolution rate.The dissolution rates were found to be lowest at near-neutral pH and to increase at both low and high pH. A rate equation based on transition-state theory (TST) was used to calculate dissolution rate constants and reaction order with respect to pH over two pH intervals at each temperature. At 250C between pH 1 and pH 7 based on the Si release rate the log rate constant for glass dissolution (g glass/m20d) was −0.77 and the order with respect to pH was −0.48. Between pH 7 and pH 13 the log rate constant for glass dissolution was −8.1 and the order with respect to pH was +0.51. The measured simple glass dissolution rate constants compare very well with constants estimated by fitting the same TST equation to experimental results obtained for SRL-165 glass and to dissolution rate estimates made for synthetic basaltic glasses.

Modelling The Alteration of Son-68 Glass with Nearfield Materials

2006 ◽  
Vol 932 ◽  
Author(s):  
G. de Combarieu ◽  
P. Barboux ◽  
N. Godon ◽  
Y. Minet ◽  
S. Gin
Keyword(s):  
Dissolution Rate ◽  
Clay Minerals ◽  
Metallic Iron ◽  
Pure Water ◽  
Comprehensive Description ◽  
Saturation State ◽  
Glass Dissolution ◽  
Surrounding Environment ◽  
Precipitated Phases

ABSTRACTThe model tested in this paper couples glass dissolution rate and geochemistry in the surrounding environment, thus leading to the comprehensive description of the interactions between the glass and the minerals and their transformations. Leaching of glass is simulated at 90°C and S/V=80 cm-1 in pure water or with iron from the canister and overpack or with argillite. The glass dissolution is described with an affinity law with respect to a nontronite-like phase, which saturation state depends on Si, Al, Fe, Na and Ca activities. The simulations results allow to reproduce both the decrease of the initial alteration rate and the so-called residual regime while the composition of the alteration layers are explained in terms of precipitated phases. In presence of metallic iron, the corrosion does not affect much glass dissolution rate if silica sorption is neglected. On the contrary, in presence of argillite, the alteration is enhanced by the dissolution of primary clay minerals and the precipitation of feldspar, K-zeolite and clay minerals.

Effect of ZrO2 on the glass durability

2002 ◽  
Vol 713 ◽  
Author(s):  
M. Lobanova ◽  
A. Ledieu ◽  
P. Barboux ◽  
F. Devreux ◽  
O. Spalla ◽  
...  
Keyword(s):  
Experimental Data ◽  
Dissolution Rate ◽  
Pure Water ◽  
Final Concentration ◽  
Leaching Tests ◽  
Borosilicate Glasses ◽  
Silica Network ◽  
Dissolution Tests ◽  
Short Times ◽  
Initial Dissolution Rate

ABSTRACTBorosilicate glasses were prepared with the molar composition 70 SiO2-15 Na2O-15B2O3-n ZrO2 with n ranging from 0 to 10. The glasses were studied by conventional static dissolution tests of powders at 90°C in pure water and in buffered solutions for long times (months) and short times (minutes). During the first minutes of alteration in a buffered solution, sodium is rapidly leached until its loss becomes controlled by the silicon hydrolysis. The experimental data show that the introduction of zirconium drastically reduces the initial dissolution rate (Vo) of the glass. Zirconium strengthens the silica network but also strongly modifies the porous layer morphology. In the case of glasses with small Zr contents (less than 2%), the silica dissolution rate decreases but the formation of a passivating alteration layer is also delayed. As a result, small amounts of zirconium paradoxically decrease the loss of silica but increase the final loss of sodium and boron in the static leaching tests. Larger zirconium contents (above 5%) increase the durability of the glass regarding the initial dissolution rate and the final concentration of all elements.

scholarly journals The fate of Si and Fe while nuclear glass alters with steel and clay

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
C. Carriere ◽  
P. Dillmann ◽  
S. Gin ◽  
D. Neff ◽  
L. Gentaz ◽  
...  
Keyword(s):  
Dissolution Rate ◽  
Protective Layer ◽  
Glass Dissolution ◽  
A Value ◽  
Waste Forms ◽  
Controlling Mechanism ◽  
Geological Repository ◽  
The Mean ◽  
High Level ◽  
Initial Dissolution Rate

AbstractThe French concept developed to dispose high-level radioactive waste in geological repository relies on glassy waste forms, isolated from the claystone host rock by steel containers. Understanding interactions between glass and surrounding materials is key for assessing the performance of a such system. Here, isotopically tagged SON68 glass, steel and claystone were studied through an integrated mockup conducted at 50 °C for 2.5 years. Post-mortem analyses were performed from nanometric to millimetric scales using TEM, STXM, ToF-SIMS and SEM techniques. The glass alteration layer consisted of a crystallized Fe-rich smectite mineral, close to nontronite, supporting a dissolution/reprecipitation controlling mechanism for glass alteration. The mean glass dissolution rate ranged between 1.6 × 10−2 g m−2 d−1 to 3.0 × 10−2 g m−2 d−1, a value only 3–5 times lower than the initial dissolution rate. Thermodynamic calculations highlighted a competition between nontronite and protective gel, explaining why in the present conditions the formation of a protective layer is prevented.

On the Kinetics and Mechanism of Spontaneous Intramolecular Reduction of the Central Metal Ion in K2[Mn(IV)-2-α-hydroxyethyl isochlorin e4] Acetate in Aqueous Alkaline Solutions and its Relation to the Binding Sites of Manganese in Photosynthesis

1975 ◽  
Vol 30 (5-6) ◽  
pp. 327-332 ◽  
Author(s):  
Gerhard Vierke ◽  
Manfred Müller
Keyword(s):  
Electron Transfer ◽  
Metal Ion ◽  
Reaction Rates ◽  
Bimolecular Reaction ◽  
Reduction Reaction ◽  
Alkaline Solutions ◽  
Central Metal ◽  
Pseudo First Order Reaction ◽  
Spontaneous Reduction ◽  
Acid Base Equilibrium

Abstract Spectrophotometric investigation of the kinetics of the spontaneous reduction of the central metal ion in K2[Mn (IV)-2-α-hydroxyethyl-isochlorine e4] acetate in aqueous alkaline solution in the absence of any reducing agent reveals that it is a pseudo-first order reaction which is specifically hydroxide ion catalyzed. The pKα-value of the acid-base equilibrium has been estimated to be 14.4. Electron transfer to the central metal ion is the rate limiting step. The measurements of its temperature dependence yields an activation enthalpy of ∆H‡ = 12 kcal/mol and an entropy of activation ∆S‡ = - 30 e.u. thus indicating that the electron transfer step is a bimolecular reaction. The most likely reactant is water. The reduction reaction does not take place with appreciable reaction rates at physiological pH. Thus, when bound to a suitable ligand of the chlorin type, Mn (IV)-compounds are sufficiently stable with respect to autoxidation to play some role in biological redox reactions as postulated recently for the photoreactivation process of the water splitting system in photosynthesis.

Solvent effects on the reactivity of solvated electrons with ammonium and nitrate ions in 1-butanol–water solvents

1993 ◽  
Vol 71 (9) ◽  
pp. 1303-1310 ◽  
Author(s):  
Ruzhong Chen ◽  
Gordon R. Freeman
Keyword(s):  
Solvent Effects ◽  
Pure Water ◽  
Reaction Rates ◽  
Dielectric Relaxation Time ◽  
Unusual Behavior ◽  
Solvated Electrons ◽  
Water Solvent ◽  
Electrical Conductances ◽  
Average Size ◽  
Effective Reaction

Values of the rate constants, k2 (106 m3 mol−1 s−1), of solvated electrons,[Formula: see text] with several related salts, in pure water and pure 1-butanol solvents at 298 K are, respectively, as follows: LiNO3, 9.2, 0.19; NH4NO3, 10, 8.3; NH4ClO4, 1.5 × 10−3, 12 in 20 mol% water; LiClO4, 1.0 × 10−4, < 1.0 × 10−4. The value of [Formula: see text] in water solvent is 48 times larger than that in 1-butanol solvent, whereas [Formula: see text] in water is 10−4 times smaller than the value in 1-butanol. This enormous reversal of solvent effects on [Formula: see text] reaction rates is the first observed for ionic reactants. The solvent participates chemically in the [Formula: see text] reaction, and the overall rate constant increases with increasing viscosity and dielectric relaxation time. This unusual behavior is attributed to a greatly increased probability of reaction of an encounter pair with increasing duration of the encounter. Effective reaction radii κRr for [Formula: see text] and [Formula: see text] were estimated with the aid of measured electrical conductances of the salt solutions in all the solvents. Values of κRr are (2–7) × 10−10 m, except for NH4,s+ in 100 and 99 mol% water, which are 2.6 and 2.7 × 10−14 m, respectively. The effective radii of the ions for mutual diffusion increase with increasing butanol content of the solvent, from ~50 pm in water to ~150 pm in 1-butanol, due to the increasing average size of the molecules that solvate the ions.

scholarly journals The effect of S53P4-based borosilicate glasses and glass dissolution products on the osteogenic commitment of human adipose stem cells

PLoS ONE ◽  
2018 ◽  
Vol 13 (8) ◽  
pp. e0202740 ◽  
Author(s):  
Miina Ojansivu ◽  
Ayush Mishra ◽  
Sari Vanhatupa ◽  
Miia Juntunen ◽  
Antonina Larionova ◽  
...  
Keyword(s):  
Stem Cells ◽  
Adipose Stem Cells ◽  
Borosilicate Glasses ◽  
Glass Dissolution ◽  
Human Adipose Stem Cells

Measurement of Glass Corrosion in Boom Clay Disposal Conditions: First Results of the Experimental Programme 2000-2003 of SCK•CEN

2003 ◽  
Author(s):  
Karel Lemmens ◽  
Marc Aertsens ◽  
Ve´ra Pirlet ◽  
Norbert Maes ◽  
Hugo Moors ◽  
...  
Keyword(s):  
Low Temperature ◽  
Dissolution Rate ◽  
Near Field ◽  
Glass Frit ◽  
Glass Mass ◽  
Boom Clay ◽  
Glass Dissolution ◽  
Mass Losses ◽  
Dissolution Behaviour ◽  
First Results

To estimate the lifetime of vitrified high level waste (HLW-glass) in Boom Clay disposal conditions, the dissolution behaviour of waste glass has been studied with experiments performed in surface laboratories and in the HADES underground research facility of SCK·CEN since 1980. We present the main topics and first results of the SCK·CEN programme 2000–2003. This programme focuses on the following items: (1) the diffusion/sorption/precipitation of silica in Boom clay or backfill clay, (2) demonstration of glass dissolution behaviour in realistic test conditions, (3) the effect of presaturation of the clay with silica, and (4) the estimation of near field concentrations of critical isotopes. The experiments have shown so far that Si, released by the glass, is effectively immobilized by Boom Clay, but it can nevertheless diffuse into the clay without immediately precipitating. The dissolution rate of glass SON68 and SM539 is determined in Boom Clay at in situ density and at 30°C (this is the long-term temperature expected near the waste glass packages in a Boom Clay repository). The dissolution rates, based on glass mass losses, are constant during the first year, at ∼ 0.010 g.m−2.day−1 for glass SON68 and ∼ 0.012 g.m−2.day−1 for glass SM539. The addition of glass frit causes a decrease of the glass dissolution rate, both with glass SON68 and SM539, and both in Boom Clay and in FoCa-clay. In FoCa-clay at high density with glass frit, the dissolution rates, based on glass mass losses, after 8 months at 30°C are ∼ 0.001 g.m−2.day−1 (SM539) and ∼0.005 g.m−2.day−1 (SON68). Because the experiments performed in Boom Clay and FoCa-clay with glass frit simulate realistic conditions (high clay density, low temperature), they can be used to estimate the maximum glass dissolution rate in a (Boom) clay repository. The corresponding minimum lifetime of a glass canister, calculated with the SCK·CEN code for lifetime predictions, is of the order of 105 to 106 years, if we neglect the internal glass surface area (due to cracking). In more diluted clay suspensions with glass frit, the glass dissolution rate is 10−4 to 10−5 g.m−2.day−1 or even zero. This would correspond to a lifetime of >>106 years. So far, there is no indication that the addition of glass frit leads to secondary phase formation at low temperature (30–40°C). Leach experiments with doped glasses SON68 and SM539 suggest that the maximum concentrations of most critical radionuclides in near field conditions are lower than the best estimate solubilities used for performance assessment studies in Boom Clay. For Se, relatively high concentrations were measured, though. The research programme for the underground laboratory is not discussed.

Sign in / Sign up

Export Citation Format

Share Document