Effects of Ion-Exchange and Hydrolysis Mechanisms on Lead Silicate Glass Corrosion

Rahimi, Rafi Ali; Sadrnezhaad, S.K.

doi:10.5006/0528

Cited by 10 publications

(11 citation statements)

References 16 publications

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“…where C in is the initial concentration of toxic metals in the glaze and L is the thickness of glaze. [9][10][11]. We obtained a solution for small values of the time expressed by the expansion in negative exponentials:…”

Section: Mathematical Model Of Migration Of Toxic Metalsmentioning

confidence: 99%

“…Glazes are nearly 100% glass . Many investigations on the dissolution (or corrosion) of lead silicate glasses in water and aqueous acid solutions have indicated that the corrosion of lead silicate glasses could be described by two simultaneous processes: (a) ion exchange reaction occurring in the glass/solution interface between hydrogen bearing species (H + , H 3 O + and H 2 O) from water or aqueous acid solutions and glass network modifier ions (Na + , K + , Ca 2+ , Mg 2+ , Pb 2+ and Cd 2+ ), which can be postulated in Equation , and (b) glass network dissolution (matrix dissolution) via hydrolysis reaction, which can be described in Equations and :

\equiv normalS normali - normalO - normalR + H_{3} O^{+} \to \equiv normalS normali - normalO - normalH + R^{+} + H_{2} normalO

\equiv normalS normali - normalO - normalS normali \equiv + H_{2} normalO \to 2 ((), \equiv normalS normali - normalO - normalH)

\equiv normalS normali - normalO - normalS normali {(O H)}_{3} + {normalO normalH}^{-} \to \equiv normalS normali - O^{-} + normalS normali {(O H)}_{4}

in which, letter R represents the monovalent modifier cation. The mechanism of silicate glass corrosion by liquids involves competition between ion exchange and matrix dissolution, and at pH <5, ion exchange is the predominant mechanism; at pH >9, matrix dissolution is predominant; however, the corrosion is a minimum when pH is between 5 and 9 …”

Section: Introductionmentioning

confidence: 99%

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Migration Model of Toxic Metals from Ceramic Food Contact Materials into Acid Food

Dong

Liu

2015

Packag Technol Sci

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Migration studies of lead and cadmium from ceramic food contact materials into acid food simulants were conducted under various time-temperature conditions to investigate the kinetics of the leaching of lead and cadmium. A mathematical model based on one-dimensional Fickian diffusion theory was derived in order to describe the migration behaviour of lead and cadmium. Moreover, diffusion coefficients of toxic metals were obtained by fitting the short-time (24 h) migration data to the model. Comparisons of model solutions with experimental data obtained from the medium-time tests (up to 600 h) and long-time tests (up to 130 days) were carried out to verify the proposed model and the values of diffusion coefficients obtained from the short-time test. Results show that the model fits the experimental data obtained under 20 and 40°C well but fails to fit the experimental data at 60°C. This indicates a change of the migration mechanisms from ion exchange to glass network dissolution as a result of higher temperature. Furthermore, results of migration experiments also reveal that the effects of temperature on the diffusion of lead and cadmium follow the Arrhenius law and that the leaching amounts of lead and cadmium decrease with pH value of the food simulant.

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Section: Mathematical Model Of Migration Of Toxic Metalsmentioning

confidence: 99%

\equiv normalS normali - normalO - normalR + H_{3} O^{+} \to \equiv normalS normali - normalO - normalH + R^{+} + H_{2} normalO

\equiv normalS normali - normalO - normalS normali \equiv + H_{2} normalO \to 2 ((), \equiv normalS normali - normalO - normalH)

\equiv normalS normali - normalO - normalS normali {(O H)}_{3} + {normalO normalH}^{-} \to \equiv normalS normali - O^{-} + normalS normali {(O H)}_{4}

Section: Introductionmentioning

confidence: 99%

Migration Model of Toxic Metals from Ceramic Food Contact Materials into Acid Food

Dong

Liu

2015

Packag Technol Sci

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“…Numerous empirical studies have been carried out to examine the Pb leaching from glass or from glass ceramic in reactive environments, particularly in contact with different actual beverages or simple synthetic solutions such as acetic acid or nitric acid [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] . In commercial lead crystal glasses, it has generally been observed that the release of alkalis and Pb ions exhibited a square root time dependence through a diffusion process 11,15,17,18 .…”

Section: Introductionmentioning

confidence: 99%

Structure and Chemical Durability of Lead Crystal Glass

Angeli

Jollivet

Charpentier

et al. 2016

Environ. Sci. Technol.

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Silicate glasses containing lead, also called lead crystal glasses, are commonly used as food product containers, in particular for alcoholic beverages. Lead's health hazards require major attention, which can first be investigated through the understanding of Pb release mechanisms in solution. The behavior of a commercial crystal glass containing 10.6 mol % of PbO (28.3 wt %) was studied in a reference solution of 4% acetic acid at 22, 40, and 70 °C at early and advanced stages of reaction. High-resolution solid-state O andSi NMR was used to probe the local structure of the pristine and, for the first time, of the altered lead crystal glass. Inserted into the vitreous structure between the network formers as Si-O-Pb bonds, Pb does not form Pb-O-Pb clusters which are expected to be more easily leached. A part of K is located near Pb, forming mixed Si-O-(Pb,K) near the nonbridging oxygens. Pb is always released into the solution following a diffusion-controlled dissolution over various periods of time, at a rate between 1 and 2 orders of magnitude lower than the alkalis (K and Na). The preferential release of alkalis is followed by an in situ repolymerization of the silicate network. Pb is only depleted in the outermost part of the alteration layer. In the remaining part, it stays mainly surrounded by Si in a stable structural configuration similar to that of the pristine glass. A simple model is proposed to estimate the Pb concentration as a function of glass surface, solution volume, temperature, and contact time.

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“…After the first hour, the pH of the medium is ~13. This value favored the silica layer dissolution, but also the formation of a depleted layer with large thickness and lead precipitates that could cause the eventual slowing of the ionic interdiffusion leading to a stable condition 36 .…”

Section: Glass Behavior In Aqueous Solutionmentioning

confidence: 99%

“…The degradation mechanism of high-lead glasses (> 40 wt. %) has been studied in acidic conditions [30][31][32][33][34][35][36] , mainly to avoid the poisoning by lead as a consequence of drinking wine (0.1-0.3 g/l acetic acid 37 ) in lead-crystal vessels [30][31][32]38 . However, there is not a systematic study about the alteration of these glasses in humid atmospheres, as happens in some collections of historical glasses without the correct preventive conservation measures or exposed to external environments.…”

Section: Introductionmentioning

confidence: 99%

Hydrolytic resistance of K₂O–PbO–SiO₂ glasses in aqueous and high‐humidity environments

2020

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Some historical glasses (lead-wood ash glasses, lead-crystal glasses…) are silicate glasses with high content of lead and potassium. This work presents the evaluation of the chemical stability of high-lead glasses in a high relative humidity atmosphere and as result of aqueous immersion.In both situations, the alteration mechanism begins with the lixiviation of alkali metal and lead ions, followed by the hydrolytic attack of the silica glass network. According to the results, the glasses with a higher content of lead show the fastest degradation due to their higher hygroscopicity. Environmental CO2 can be dissolved in the adsorbed water and favor the formation of intermediate degradation compounds.

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Effects of Ion-Exchange and Hydrolysis Mechanisms on Lead Silicate Glass Corrosion

Cited by 10 publications

References 16 publications

Migration Model of Toxic Metals from Ceramic Food Contact Materials into Acid Food

Migration Model of Toxic Metals from Ceramic Food Contact Materials into Acid Food

Structure and Chemical Durability of Lead Crystal Glass

Hydrolytic resistance of K₂O–PbO–SiO₂ glasses in aqueous and high‐humidity environments

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Effects of Ion-Exchange and Hydrolysis Mechanisms on Lead Silicate Glass Corrosion

Cited by 10 publications

References 16 publications

Migration Model of Toxic Metals from Ceramic Food Contact Materials into Acid Food

Migration Model of Toxic Metals from Ceramic Food Contact Materials into Acid Food

Structure and Chemical Durability of Lead Crystal Glass

Hydrolytic resistance of K2O–PbO–SiO2 glasses in aqueous and high‐humidity environments

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Hydrolytic resistance of K₂O–PbO–SiO₂ glasses in aqueous and high‐humidity environments