Ceramics-Silikáty 41, (2) 61 - 65 (1997)

Transfer of glass components into solution was studied on borosilicate glass Simax and on soda-lime-silica container glass, using aqueous solutions of citrate (0.1 to 4 wt.%) and salts of several organic acids (lactic, tartaric, oxalic, ascorbic, gluconic and EDTA). The powdered samples of the glasses were extracted (for 4 to 24 hours) at 98 °C, concentrations of SiO₂ and CaO were determined in the extracts. The results showed that neutral aqueous solutions of salts of all the organic acids in question promoted significantly the dissolution of both types of glasses as compared to dissolution in distilled water. The effect of citrate was studied in detail. Even low concentrations of citrate (0.1 wt.%) speeded up transfer of SiO₂ and of CaO into solution. In the case of soda-lime glass, the resulting SiO₂/CaO ratio in the leachates (citrate solutions) was very close to the ratio of the components in the glass, which is indicative of congruent dissolution of glass. The results obtained with both multicomponent types of glasses are in good agreement with the findings of a previous study concerned with similar effects on silica glass.