• Journal of the Korean GEO-environmental Society
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• v.11 no.7
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• pp.45-49
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• 2010

We have developed and demonstrated the use of a new kinetic method as an analytical tool for the measurement of $HO_2{\cdot}/O_2{\cdot}^-$. This new method is based on the reduction of $Fe^{3+}$-Ethylene Diamine Tetra Acetate, EDTA) into $Fe^{2+}$-EDTA by $HO_2{\cdot}/O_2{\cdot}^-$ and the well-known Fenton-like reaction of $H_2O_2$ and $Fe^{2+}$-EDTA to yield the hydroxyl radicals ($OH{\cdot}$). Since this method for $HO_2{\cdot}/O_2{\cdot}^-$ shows high sensitivity and allows a simple calibration system, it can contribute significantly to understanding the basic functions of $HO_2{\cdot}/O_2{\cdot}^-$ in advanced oxidation processes for water treatment. Moreover, the present technique has the advantage of using inexpensive and easily available nonenzymatic reagents and of being insensitive to the moderate concentration of possible interferences often found in aqueous phase.

• Journal of the Korean GEO-environmental Society
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• v.11 no.8
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• pp.41-47
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• 2010

This study was conducted to assess the applicability of pilot scale system and to evaluate the treatment efficiency on operational parameters such as humic acid concentration, initial pH and air flow rate on the ozone/peroxyl radical reaction system. The decolorization of ozone/peroxyl radical system was higher than that of only process. Removal efficiency of ozone/peroxyl radical system was generally increased with the increase of intial concentration of humic acid but decreased over the range of 30mg/L. Treatment efficiency of HA at acid pH was smaller compared to that of neutral or basic pH and increased with increasing the air flow rate from 1L/min to 3L/min. In pilot-scale test, average removal of TOC and $COD_{Cr}$ was about 70% and 60%, respectively and ozone/peroxyl radical reaction system was indicated a potential in water treatment application.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.6
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• pp.779-790
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• 2006

This study examines relative contributions of volatile organic compounds (VOCs) to the formation of hydroxyl (OH) and peroxy radicals such as $HO_2$ and $RO_2$ during the intensive sampling period (Jun. $1{\sim}30$, 2004) in the air of Seoul metropolitan area. As to the contribution of VOCs to $HO_x$ levels, the impact of individual VOC concentration change on $HO_2$ concentration change was more than an order of magnitude higher than that on OH concentration change during the study period. The contribution of change in isoprene concentration to $HO_2$ concentration change was 38 times higher than OH and that in the concentration of alkene compounds to $HO_2$ concentration change was 31 times higher than OH. Moreover, the concentration changes of isoprene and aromatic compounds (AROM) played significant roles in $HO_x$ concentration changes. On the other hands, aldehydes (ALD2) and alkanes (ALKA) showed anti-correlation (negative) in $HO_x$ concentration changes with low contribution ($-4{\times}10^{-3}$ pptv/ppbv (OH) and $-58{\times}10^{-3}$ ($HO_2$) for ALD2; $-1{\times}10^{-3}$ (OH) and $-15{\times}10^{-3}$ ($HO_2$) for ALKA). Unlike other VOCs, $C_2H_6$ and $C_3H_8$ showed positive or negative contribution to peroxy radicals, depending on ambient air conditions. The contribution of VOC concentration changes to changes in $CH_3O_2$ and $RO_2$ concentration showed similar pattern to $HO_x$ contribution.