Corrosion of Lead Glasses in Acid Media: I, Leaching Kinetics

Abstract

The leaching kinetics of lead glasses (25 to 35 mol% PbO-75 to 65 mol% SO,; some with K 2 0 and additions) were determined in 10% acetic acid. Except for a ternary glass (Si0,-PbO-KZO) which had a linear dependence on time, all compositions exhibited a linear dependence on the square root of time for the amount of Pb and K removed. Increasing the SO,: PbO ratio or the AI,O,i content improved the durability whereas adding K,O to a binary PbO-Si02 glass greatly increased the corrosion rate. Activation energies for the rates of Pb and K removal were determined for three compositions and it was deduced that the diffusion of H+ controlled the leaching for binary and 4-component glasses whereas dissolution of the silica network was rate-controlling for the ternary.

Electrochemical Characterization of Archaeological Tin‐Opacified Lead‐Alkali Glazes and Their Corrosion Processes

“…In addition to alkali ions, the Pb 2þ cations, acting as network modifiers, are significantly diffused and replaced by H þ ions from the corrosion medium [9 -11]. Accelerated ageing experiments aimed to the study of specific process of corrosion of lead and lead-alkali glasses performed by Wood and Blanchere [12,13] indicated that the removal of Pb 2þ and K þ from leadpotassium glasses approaches two different dependences on time: at short times, a proportionality of the released amount of ions with the square root of time was obtained, diffusion acting as a rate-determining factor; at long times, the amount of released ions was found to be proportional to time, suggesting that the silica dissolution is the rate-limiting factor instead of proton or ion diffusion.…”

Corrosion of Glass

“…As for alkali silicate glasses, a square root of time rate law was followed by a linear rate law for optical lead silicate glasses (SiO 2 65 mol %, PbO 25-35 mol %, K 2 O 0-10 mol %, Al 2 O 3 0-2 mol %) under acetic acid static corrosion conditions [217]. Activation energies were $50 kJ/mol.…”

“…Activation energies were $50 kJ/mol. As for alkali ions in alkali silicate glasses, diffusion-controlled surface depletion profiles were observed for Pb release from the glass [218].…”

Electrochemical Fingerprint of Archeological Lead Silicate Glasses Using the Voltammetry of Microparticles Approach

“…Lead silicate glasses are also of considerable interest for their peculiar thermal, optical, and mechanical properties, and their structural chemistry has drawn attention, in particularly as regards Pb 2+ leaching . In fact, different proposals have been put forward about the structural role played by lead centers as some act as network modifiers with a sixfold coordinated environment, while others act as network formers and have a lower coordination number .…”