US EPA

3220148 

Journal Article 

Attack on soda-lime-silica glass bottles by acetic, citric and oxalic acids 

Ahmed, AA; Youssof, IM 

1997 

70 

3 

76-85 

WOS:A1997WU39600002 

The corrosion resistance of soda-lime-silica glass bottles
toward the action of aqueous solutions of citric, acetic and oxalic acids was studied and
compared with that toward HCl and water. The corrosion resistance was tested by subjecting the
internal surface of the bottles to the action of solutions of different concentrations of the
organic acids at 95 degrees C for periods in the range of 15 min to 6 h. The quantities of Na2O
and SiO2 extracted from the bottles under the conditions of attack were taken as a measure of the
resistance to corrosion. The results obtained indicated that the extraction of Na2O by solutions
of low concentrations of the different acids and water can be arranged in the following order:
H2O > citric acid > acetic acid > HCl > oxalic acid. Such behaviour was found to follow the order
of the solubility of the corresponding sodium salts formed with the aqueous solutions rather than
the proton availability in these solutions. The relative magnitude of dissolution of SiO, was
found to follow another order: H2O > HCl > oxalic acid > citric acid > acetic acid. The
decreasing solubility of SiO2 by the organic acids, in comparison with that by HCl or water, was
attributed to the formation of oxalate, citrate and acetate complexes with silica which cover the
glass surface and retard further dissolution of silica. Differences between the various organic
acids in the dissolution of Na2O or SiO2 were not observed by increasing their concentrations.
This behaviour was attributed to the increase in the concentration of the organosilicon compound
formed which is adsorbed on the glass surface acting as an effective barrier to further
dissolution of glass.