The ROH,UV Concept to Characterize and the Model UV/H2O2 AOP Process in Natural Waters
Authors:
- Erik J. Rosenfeldt - Hazen and Sawyer
- Karl G. Linden - Department of Civil and Environmental Engineering, Duke University
A new concept is introduced to characterize and model the UV/H2O2 advanced oxidation process (AOP) in water. Similar to the RCt concept used to describe OH radical exposure per ozone dose, the ROH,UV concept is defined as the experimentally determined -OH radical exposure per UV fluence.
ROH,UV was determined by examining the destruction of a probe compound, para-chlorobenzoic acid in four different waters: DI water and three natural waters. ROH,UV was found to be affected greatly by water quality, specifically background ¥OH radical scavenging, which competed for the formed -OHradical with the probe compound, and background UV absorbance, which screened UV irradiation from the hydrogen peroxide.
The ROH,UV values determined in the experiments using low-pressure Hg lamp were greater than those for the medium-pressure Hg lamp . Finally, the ROH,UV concept was utilized to calculate an overall scavenging factor for each water matrix, and this was successfully utilized in conjunction with the steadystate -OH radical model to improve the prediction of the oxidation of endocrine-disrupting compounds 17-R-ethinyl estradiol and 17-â-estradiol in the natural waters.
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