Investigation of the Degradation of Aqueous Ethylene Glycol and Propylene Glycol Solutions Using Ion Chromatography.
Investigation of the Degradation of Aqueous Ethylene
Glycol and Propylene Glycol Solutions Using Ion
Chromatography.
(1136 K)
Rossiter, W. J., Jr.; Godette, M.; Brown, P. W.; Galuk,
K. G.
Solar Energy Materials, Vol. 11, 455-467, 1985.
Keywords:
ethylene glycol; propylene glycol; chromatography;
degradation products; thermal oxidation; solar
collectors; copper; degradation; metals
Abstract:
Aqueous solutions of ethylene glycol and propylene
glycol produce acidic degradation products
upon thermal oxidation. This results in a decrease in pH
of the aqueous solutions which could
accelerate the corrosion of metalllic components of
solar collectors. The increase in the concentrations
of degradation products in solution was measured over
time using the Ion Chromatography
Exclusion (ICE) method of analysis. Variables affecting
the thermal oxidation considered in the
investigation were temperature, the presence of metals
and oxidative conditions (aeration/deaeration).
Acidic degradation products were produced under all
conditions. The presence of metallic
copper in aerated glycol solutions resulted in the
greatest extent of degradation. Comparisons were
made between the pH values of the thermal oxidatively
degraded glycol solutions and the
concentrations of degradation products. It was found
that different solutions having comparable
pH values contained significantly different amounts of
degradation products. It was concluded
that the extent of degradation of the glycol cannot be
used as an indicator of the magnitude of the
decrease in pH which the glycol solution may undergo
during thermal oxidation in the presence of
metals.
