Leaching studies of soda-lime-silica glass using deuterium- and 18O-enriched solutions

With a glass of composition (in mol%) 74 SiO2,16 NaO, 10 CaO, various leaching experiments were conducted, in which besides solutions of normal isotopic composition deuterium- and 18O-enriched solutions were used. The concentration profiles of deuterium, hydrogen, and 18O in the sample were measured with nuclear analyzing techniques. A distinct H/D isotope effect was observed, showing that hydrogen takes part in the rate-determining step of leaching. The measured ratio of 18O uptake to hydrogen uptake during leaching gives evidence for exchange of oxygen between the glas network and water molecules contained in the leached layer. From measurements on the exchange of hydrogen and oxygen between solution and leached layer, a high mobility of water molecules in the leached layer and evidence for condensation of silanol groups was found. (orig.)