DISSOLUTION RATES OF COMMERCIAL SODA-LIME AND PYREX BOROSILICATE GLASSES - INFLUENCE OF SOLUTION PH

Dissolution rates of two commercial soda-lime silicate glasses and Pyrex borosilicate glass (Corning 7740) have been measured as a function of pH. The dissolution rate was constant with time and increased with increase in pH from 4 to 9. The activation energy for dissolution was nearly constant with pH for the Pyrex borosilicate glass, and decreased somewhat as pH increased for the soda-lime glasses. The openness of the glass surface influences strongly the rate of dissolution. The solubility of silica as a function of pH increases at pH above 8 but does not seem to be quantitatively related to dissolution rate. Other possible influences on this rate are briefly considered.