Decomposition of Ethylene Glycol under Ultraviolet Irradiation by the Combined Use of Ozone Oxidation Method and Electrolytic Method

Abstract

Decomposition of ethylene glycol under ultraviolet irradiation by the combined use of an ozone oxidation method and an electrolytic one was studied by changing the concentration of ethylene glycol, that of ozone in the feed gas, the current density, the quantity of added NaC1 and the ultaviolet intensity of a low pressure mercury lamp. The overall reaction rate was represented as follows.
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where k is the rate constant, I is the ultraviolet intensity of a low pressure mercury lamp, F is the concentration of ozone in the feed gas, and C is that of ethylene glycol. Glyoxylic acid, glyoxal, glycolaldehyde, formaldehyde and formic acid were detected as decomposition products, and the decrease of the total organic carbon (TOC) was also observed. The timedependence of the TOC and that of the product composition suggested that the TOC removal via the formation of formic acid is dominant in the electrolytic process, and that via the formation of oxalic acid is dominant by the ultraviolet irradiation, The TOC removal has been found particularly effective at high concentrations of ethylene glycol.