Corrosion of silica glass by aqueous solutions of organic compounds

The effect of solutions of salts of organic acids (citric, oxalic, lactic, ascorbic, tartaric, gluconic, ethylene- diaminetetraacetic) on the dissolving of silica glass was studied on powdered samples of the glass at 98 degrees C. All of the compounds were found to accelerate the dissolution of silica glass in neutral and alkaline solutions, and the effect decreased in the following sequence: citrate, oxalate, lactate, disodium salt of EDTA, ascorbate, tartrate, gluconate. More detailed attention was paid to citrate. Even its low concentrations in the leaching solution (0.1 wt.%) promote significantly the dissolution of silica glass. Concentration of SiO2 in the citrate leachate increases with increasing pH of the solution. The rate of dissolution of silica glass in citrate solution is markedly higher than that of silica in crystalline form (quartz crystal).