• 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.

• Bulletin of the Korean Chemical Society
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• v.23 no.9
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• pp.1187-1188
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• 2002

• Journal of the Korean Applied Science and Technology
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• v.12 no.2
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• pp.145-150
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• 1995

The Kinetics velocity for hydrolysis reaction of vanillylidene imine derivatives has been measured by ultra-violet ray spectrophotometer in 20wt% $dioxane-H_2O$ at $25^{\circ}C$. It was measured the reaction rate Constant of vanillylidene imine derivatives that can be applied widely following to pH-change at $25^{\circ}C$. Final products that hydrolyzed the vanillylidene imine certified in vanillin and aniline derivative, and the effect of substitution radical that has affected on hydrolysis reaction was largely promoted to reaction rate by electron attrating group in acidity and electron donoring group in basic. From the results of rate constant to hydrolysis reaction, substituent radical effect and final products. It has certified the hydrolysis reaction mechanism of vanillylidene imine derivatives.

• Journal of the Korean Applied Science and Technology
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• v.39 no.4
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• pp.535-541
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• 2022

The radical reaction position was calculated by varying the calculation level for ACEL and ANT, which are detected with the highest frequency and concentration in PAHs pollution sites. The results of each calculation level were compared and evaluated with the existing literature. HF, B3LYP, B3LYP-D, and MP2 were used as the method for each level used for calculation. Except for HF, the MK charge by B3LYP, B3LYP-D, and MP2 was consistent with the experimental results. It was found that the dispersion effect was negligible in the calculation of ACEL and ANT because the calculation results by the B3LYP and B3LYP-D methods were the same. In particular, it was found that the MK charge calculation result by MP2 agrees well with the product/PAH ratio obtained as a result of the experiment. Considering the calculation cost, it would be preferable to use B3LYP to predict the radical reaction site of ACEL and ANT. However, considering the product/PAH ratio, it takes more time to calculate, but it is judged that it is better to use the MP2.

• Journal of the Korean Chemical Society
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• v.24 no.1
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• pp.34-43
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• 1980

The reaction of thianthrene cation radical perchlorate with thioxanthene in acetonitrile gave thianthrene and dark reddish thioxanthylium ion instead of thioxanthene cation radical. Addition of aromatic nucleophiles such as anisole, aniline, N,N-diethylaniline, catechol, ethylbenzene, to the above mixture yielded the corresponding thioxanthenes with substituent at 9 position. Reactions with dibenzo-18-crown-6-ether, diphenylmercury, and triphenylphosphine gave similar products. However, reactions with aromatics with electron-withdrawing group were either too slow or inert to such a reaction.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2000.05a
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• pp.145-148
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• 2000

• Bulletin of the Korean Chemical Society
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• v.24 no.3
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• pp.318-324
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• 2003

A time-resolved probe beam deflection (PBD) technique was employed to study the energy relaxation dynamics of photofragments produced by photodissociation of $CH_3I$ at 266 nm. Under 500 torr argon environment, experimental PBD transients revealed two energy relaxation processes; a fast relaxation process occurring within an acoustic transit time (less than 0.2 ㎲ in this study) and a slow relaxation process with the relaxation time in several tens of ㎲. The fast energy relaxation of which signal intensity depended linearly on the excitation laser power was assigned to translational-to-translational energy transfer from the photofragments to the medium. As for the slow process, the signal intensity depended on square of the excitation laser power, and the relaxation time decreased as the photofragment concentration increased. Based on experimental findings and reaction rate constants reported previously, the slow process was assigned to methyl radical recombination reaction. In order to determine the rate constant for methyl radical recombination reaction, a theoretical equation of the PBD transient for a radical recombination reaction was derived and used to fit the experimental results. By comparing the experimental PBD curves with the calculated ones, the rate constant for methyl recombination is determined to be $3.3({\pm}1.0)\;{\times}\;10^6\;s^{-1}torr^{-1}$ at 295 ± 2 K in 500 torr Ar.

• Food Science and Biotechnology
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• v.17 no.6
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• pp.1310-1315
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• 2008

This study was to investigate the influence of pH on the antioxidant activity of melanoidins formed from glucose (Glc) and fructose (Fru) with lysine enantiomers in the Maillard reaction. Melanoidins formed from D-isomers were found to be effective antioxidants in different in vitro assays with regard to the ferrous ion chelating activity, 1, l-diphenyl-2-picryl-hydrazil (DPPH) radical scavenging activities, ferric reducing/antioxidant power (FRAP), and 2,2'-azinobis(3-ethylbenothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging activity. In particular, the chelating activity of these melanoidins at a pH of 7.0 was greater than those with pH of 4.0 and 10.0. The chelating activity and DPPH radical scavenging activity of the melanoidins formed from the Glc systems were higher than those of the melanoidins formed from the Fru systems. However, the FRAP and ABTS radical scavenging activity of these melanoidins were not different according to pH level, with exceptions being the Fru systems.

• Bulletin of the Korean Chemical Society
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• v.10 no.5
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• pp.422-426
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• 1989

Triethylsilyl radical was generated by laser flash photolysis of a 1:1 (v/v)solution of triethylsliance and di-tert-butyl peroxide. The silicon centered radical was reacted with sulfides to give carbon centered radicals by displacement at sulfar. The carbon radicals were readily detected by their transient absorption spectra. The absolute rate of reaction of triethylsilyl radical with 9-fluorenylphenylsulfide, di-n-butylsulfide, di-sec-butyl, di-tert-butyl sulfide and di-n-butyl disulfide are $2.40{\pm}0.12{\times}10^8M^{-1}s^{-1}$, $11.21{\pm}0.89{\times}10^6M^{-1}s^{-1}$, $8.79{\pm}0.73{\times}10^6M^{-1}s^{-1}$, $3.29{\pm}0.18{\times}10^6M^{-1}s^{-1}$, and $3.41{\pm}0.09{\times}10^8M^{-1}s^{-1}$, respectively.

• The Korean Journal of Food And Nutrition
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• v.24 no.4
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• pp.713-719
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• 2011

The antioxidant activities of the ethanol extract of Arctium lappa were assessed by measuring the 1,1-diphenyl-2-picrylhydrazyl( DPPH) radical scavenging effect, inhibition of $Fe^{2+}$-induced lipid peroxidation, inhibition of malondialdehyde(MDA)-bovine serum albumin(BSA) conjugation reaction and antimutagenic capacities using the Ames test. The DPPH radical scavenging activity and inhibition of $Fe^{2+}$-induced lipid peroxidation of the $Arctium$ $lappa$ ethanol extract significantly increased in a dose-dependent manner. In the radical scavenging assay using DPPH, the $IC_{50}$ of the Arctium lappa extract was 296 ${\mu}g$/assay(1.29 mg of dry sample). In addition, the $IC_{50}$ in the inhibition of $Fe^{2+}$-induced lipid peroxidation was 1,759 ${\mu}g$/assay(7.65 mg of dry sample). This extract also significantly inhibited the MDA-BSA conjugation reaction with an $IC_{50}$ of 57.58 mg/assay(250 mg of dry sample). However, no inhibitory effects against the direct and indirect mutagenicities in $Salmonella$ Typhimurium TA98 and TA100 were observed. Based on these results, the ethanol extract of $Arctium$ $lappa$ was shown to display considerable antioxidative activities.