• Journal of Soil and Groundwater Environment
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• v.14 no.2
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• pp.26-32
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• 2009

In this study, the degradation of BTEX (benzene, toluene, ethylbenzene, xylene) was tested in both (Fe$^{3+}$+chelating agent)/H$_2$O$_2$system [Fe(III) 1 mM, oxalate 6 mM, H$_2$O$_2$ 3%, and pH 6] and UV/(Fe3++ chelating agent)lHzOz system [UV dose 17.4 kWhlL, Fe(III) 1mM, oxalate 6 mM,H$_2$O$_2$ 1%, and pH 6]. The types of chelating agents used in experiments were catechol, NTA, gallic, acetyl acetone, succinic, acetate, EDTA, citrate, malonate, and oxalate and the optimum chelating agent for BTEX degradation was determined. The results showed that acetate was the optimum chelating agent for BTEX degradation in both (Fe$^{3+}$+chelating agent)/H$_2$O$_2$ and UV/(Fe$^{3+}$+chelating agent)/H$_2$O$_2$ system, and UV radiation enhanced the degradation of BTEX with any types of chelating agents. Moreover, UV/(Fe$^{3+}$+chelating agent)/H$_2$O$_2$ system, which chelating agent was acetate, removed effectively mixtures of BTEX and MTBE (methyl tert-butyl ether) when the concentration of both BTEX and MTBE was 200 mg/L, respectively. In this system, BTEX was degraded completely and 85% of MTBE was degraded at the reaction time of 180 min. Therefore, UV/((Fe$^{3+}$+chelating agent)/H$_2$O$_2$ system with acetate as a chelating agent removed not only BTEX but also BTEX and MTBE, effectively.

• Food Science and Preservation
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• v.23 no.6
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• pp.859-865
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• 2016

Thise study aimed to determine the optimum antioxidant extraction conditions of dried Gugija (Lycium chinensis Mill). To determine the operational parameters, including ethanol concentration ($X_1$, 0~80%) and extraction time ($X_2$, 1~5 hr), a response surface methodology was applied to monitor brown color intensity, total phenolic compounds, ABTS radical scavenging activity, and $Fe^{2+}$ chelating activity. Coefficients of determinations ($R^2$) of the models were 0.8486~0.9214 (p<0.05~0.1) in dependent parameters. Brown color intensity of Gugija extracts reached a maximum of 0.75 (OD in 420 nm) under extraction conditions of 2.88 hr in 78.10% ethanol. Total phenolic compounds reached a maximum of $2,355{\mu}g$ under extraction conditions of 4.94 hr in 30.17% ethanol. ABTS radical scavenging activity was 13.83% at 4.61 hr and 16.21% ethanol. $Fe^{2+}$ chelating activity showed a maximum of 58.54% under extraction conditions of 3.39 hr in 0.76% ethanol. Optimum extraction conditions (5 hr extraction in 15% ethanol) were obtained by superimposing the contour maps with regards to total phenolic compounds, ABTS radical scavenging activity, and $Fe^{2+}$ chelating activity of dried Gugija. Maximum values of total phenolic compounds, ABTS radical scavenging activity, and $Fe^{2+}$ chelating activity under optimum extraction condition were $2,397{\mu}g$, 15.62% and 54.78%, respectively.

• Korean Journal of Plant Resources
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• v.22 no.4
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• pp.349-358
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• 2009

The potential use of 4 plant species, Astragalus membranaceus var. membranaceus, Senna occidentalis, Dianthus longicalyx and Plantago asiatica, as new sprout vegetables with high antioxidant function was examined in the present experiments. Seeds of above plants were allowed to germinate under light condition, and seedlings were maintained under dark condition for shoot growth in length for contain period of time. Then the seedlings were put under light for photosynthesis (greening treatment) for the period of 0${\sim}$3 days. Samples were collected to analyze the changes in antioxidant levels and activity, and it was observed that antioxidant substances were affected by greening treatments, depending on plant species. In A. membranaceus, the contents of total polyphenol was highest with no greening, total flavonoids with 3 days greening, DPPH radical scavenging effects with no greening, ABTS scavenging with 1 day greening, $Fe^{2+}$ chelating effects with no greening, and inhibitory activity against linoleic acid peroxidation with 3 day greening. In S. occidentalis, highest levels of antioxidant activity and radical scavenging effects were obtained by 2 day greening, $Fe^{2+}$ chelating effects by no greening and inhibitory activity against linoleic acid peroxidation by 1 day greening. In D. longicalyx, highest levels of antioxidant activity and $Fe^{2+}$ chelating effects were obtained by 2 day greening, $Fe^{2+}$ chelating effects by no greening and inhibitory activity against linoleic acid peroxidation by 1 day greening. In D. longicalyx, highest levels antioxidant activity and $Fe^{2+}$ chelating effects were observed with 3 day greening, and highest radical scavenging effects and inhibitory activity against linoleic acid peroxidation with no greening treatment. In P. asiatica, antioxidant activity and radicals scavenging effects were highest with 2 day greening, whereas highest chelating effects was obtained with no greening and highset inhibitory activity against linoleic acid peroxidation with 3 day greening. As the length of greening treatments influenced the antioxidant levels and function in plant species tested in this experiments, different culture methods are recommended for different plant species to get maximum health benefits out of sprout vegetables.

• Korean Chemical Engineering Research
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• v.52 no.5
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• pp.638-646
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• 2014

The effect of in-organic chelating agents with Fe(II) and Fe(III) in modified Fenton was evaluated to degradation BTEX (benzene, toluene, ethylbenzene, xylene). Citric acid and pyrophosphate were used in experimentals and an optimum chelating agent for BTEX degradation was determined. In $H_2O_2$/Fe(III)/citric acid, degradation of BTEX was decreased when concentration of citric acid was increased. In $H_2O_2$/Fe(III)/pyrophosphate, degradation of BTEX was increased when concentration of pyrophosphate was increased and degradation for BTEX was relatively high compared with $H_2O_2$/Fe(III)/citric acid. In $H_2O_2$/Fe(II)/chelating agents, degradation for BTEX was high and pH variation was minimized when molar ratio of Fe(II) and citric acid was 1:1. Optimum molar concentration of Fe(II), citric acid and $H_2O_2$ were 7 mM, 7mM and 500 mM for degradation of 100 mg/L of benzene to obtain best efficiency of $H_2O_2$, least precipitation of iron and best degradation.

• Applied Chemistry
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• v.15 no.2
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• pp.113-116
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• 2011

A sensitive and selective determination method of Fe(II) ion by luminol-H₂O₂ system using a chelating reagent has been presented. A metal ion-chelating ligand complex such as Fe(II)-diethylenetriamine pentaacetic acid (DTPA) produced higher chemiluminescence (CL) intensity as well as longer lifetime in luminol-H₂O₂ system than metal exist as free ions. Furthermore, the catalytic activity of Cu(II) and Pb (II) complexes with chelating reagents in luminol-H₂O₂ system was lost since chelating reagents act as a masking agent although free Cu(II) and Pb(II) ions have high catalytic activity. On the optimized conditions, the calibration curve of Fe(II) ion was linear over the range from 1.0×10^-7 to 2.0×10^-5 M with correlation coefficient of 0.996. The detection limit was calculated to be 4.0×10^-8 M.

• Journal of Soil and Groundwater Environment
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• v.26 no.1
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• pp.54-64
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• 2021

The chemical warfare agents (CWAs) have been developed for offensive or defensive purposes and used as chemical weapons in war and terrorism. The CWAs are exposed to the natural environment, transported through the water system and then eventually contaminate soil and groundwater. Therefore, effective decontamination technology to remediate CWAs are needed. The CWAs are extremely dangerous and prodution is strictly prohibited, therefore, it is difficult to use CWAs even in experimental purpose. In this study, 2,4-dichlorophenoxyacetic acid (2,4-D) was chosen as a model representative CWA because it is a simulant of anti-plant CWAs and one of the major component of agent orange. The optimum degradation conditions such as oxidant:activator ratio were determined. The effects of hydroxylamine and chelating agents such as citric acid (CA), oxalic acid (OA), malic acid (MA), and EDTA addition to increase Fe2+ activation were also investigated. Scavenger experiments using tert-butyl alcohol (TBA) and ethanol confirmed that although both sulfate (SO4•-) and hydroxyl radical (•OH) existed in Fe2+-persulfate system, sulfate radical was the predominant radical. To promote the Fe2+ activator effect, the effect of hydroxylamine as a reducing agent was investigated. In chelating agents assisted Fe2+-persulfate oxidation, the addition of 2 mM of CA and MA enhanced 2,4-D degradation. In contrast, EDTA and OA inhibited the 2,4-D removal due to steric hindrance effect.

• Journal of Soil and Groundwater Environment
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• v.12 no.5
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• pp.105-114
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• 2007

The most advanced oxidation processes (AOPs) are based on reactivity of strong and non-selective oxidants such as hydroxyl radical (${\cdot}OH$). Decomposition of typical DNAPL chlorinated compounds (TCE, PCE) using various advanced oxidation processes ($UV/Fe^{3+}$-chelating agent/$H_2O_2$ process, $UV/H_2O_2$ process) was approached to develop appropriate methods treating chlorinated compound (TCE, PCE) for further field application. $UV/H_2O_2$ oxidation system was most efficient for degrading TCE and PCE at neutral pH and the system could remove 99.92% of TCE after 150 min reaction time at pH 6($[H_2O_2]$ = 147 mM, UVdose = 17.4 kwh/L) and degrade 99.99% of PCE within 120 min ($[H_2O_2]$ = 29.4 mM, UVdose = 52.2 kwh/L). Whereas, $UV/Fe^{3+}$-chelating agent/$H_2O_2$ system removed TCE and PCE ca. > 90% (UVdose = 34.8 kwh/L, $[Fe^{3+}]$ = 0.1 mM, [Oxalate] = 0.6 mM, $[H_2O_2]$ = 147 mM) and 98% after 6hrs (UVdose = 17.4 kwh/L, $[Fe^{3+}]$ = 0.1 mM, [Oxalate] = 0.6 mM, $[H_2O_2]$ = 29.4 mM), respectively. We improved the reproduction system with addition of UV light to modified Fenton reaction by increasing reduction rate of $Fe^{3+}$ to $Fe^{2+}$. We expect that the system save the treatment time and improve the removal efficiencies. Moreover, we expect the activity of low molecular organic compounds such as acetate or oxalate be effective for maintaining pH condition as neutral. This oxidation system could be an economical, environmental friendly, and practical treatment process since the organic compounds and iron minerals exist in nature soil conditions.

• The Korean Journal of Pharmacology
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• v.27 no.1
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• pp.69-80
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• 1991

Inhibitory effects of quercetin and rutin on lipid peroxidation of microsomes caused by iron(II) were investigated with respect to the scavenging action for oxygen radicals produced during oxidation of iron and the chelating action for iron. Lipid peroxidation by $Fe^{2+}$ alone was markedly inhibited by quercetin or rutin in a dose dependent fashion. Lipid peroxidation by ascorbate or NADPH in the presence of $Fe^{2+}$ was almost completely inhibited by both quercetin and rutin. The peroxidative action of $Fe^{2+}$ was inhibited by SOD and DABCO and slightly inhibited by catalase, DMSO and mannitol. Quercetin and rutin inhibited oxidation of $Fe^{2+}$ which is responsible for DETAPAC and they showed a significant initial chelating effect. Quercetin and rutin effectively inhibited lipid peroxidation by $H_{2}O_{2}$ and decomposed $H_{2}O_{2}$. Both $OH{\cdot}$ production in the presence of $Fe^{2+}$ and $^1O_2$ production by U.V. irradiation were inhibited by quercetin and rutin. Lipid peroxidations by $Cd^{2+},\;Cu^{2+},\;Ni^{2+},\;Pb^{2+}$ and $Zn^{2+}$ were almost completely inhibited by quercetin. Quercetin and rutin significantly prevented the loss of sulfhydryl groups by $Fe^{2+}$. These results suggest that inhibitory effects of quercetin and rutin on the peroxidative action of $Fe^{2+}$ in the presence or absence of ascorbate and NADPH may be attributable to their scavenging action on reactive oxygen species and chelating action on iron.

• The Korea Journal of Herbology
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• v.26 no.4
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• pp.95-99
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• 2011

Objective : In this study, we demonstrate the protective effect on oxidative DNA damage of leaf extracts from Abeliophylli distichi Folium via its antioxidant activity for the establishment of new value for the herbal medicine. Methods : Abeliophylli distichi Folium leaves were extracted with hot-water and ethylacetate (EtOAC). The 1,1-diphenyl-2- picrylhydrazyl (DPPH) radical and hydroxyl scavenging assay and $Fe^{2+}$ chelating assay were performed for antioxidative effect and ${\varphi}$X-174 RF I DNA cleavage assay and intracellular DNA damage assay were used for inhibitory effect of intracellular DNA damage. Results : In DPPH, Hydroxyl radical scavenging activity and $Fe^{2+}$ chelating activity of EtOAC extracts were 94.72%, 62.88%, 41.13%, and hot-water extracts were 88.86%, 56.7%, 37.4% at 200 ${\mu}g/m{\ell}$, respectively. Also, those extracts showed protective effect of DNA damage against the oxidative stress. Conclusion : These results indicated that the leaf extracts of Abeliophylli distichi Folium can be used as a natural antioxidants, which effectively inhibits the oxidative DNA damage.

• Preventive Nutrition and Food Science
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• v.14 no.4
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• pp.323-328
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• 2009

Cryotin F could be used for hydrolyzing shrimp byproducts into bioactive ingredients, which could be used as value-added products. The objective of this study was to investigate the optimum condition for antioxidative activities of the enzymatic hydrolysate produced with Cryotin F using response surface methodology with central composite rotatable design. Shrimp byproducts (shells and heads) were hydrolyzed with Cryotin F. The experimental ranges of the independent variables for 20 experimental runs were 28.2-61.8${^{\circ}C}$ reaction temperature, pH 6-10 and 0.5-5.5% enzyme concentration. The degree of hydrolysis for the reaction products was measured. Their antioxidative activities were measured using 1,1-diphenyl-2-picryl-hydrazyl (DPPH) scavenging activity and Fe-chelating activity. The experimental method with central composite rotatable design was well designed to investigate the optimum condition for biofunctional ingredients with antioxidative activities using Cryotin F because of their high R2 values of 0.97 and 0.95 for DPPH-scavenging activity and Fe-chelating activity, respectively. Change in enzyme concentration did not significantly affect their antioxidative activities (p<0.05). Both DPPH scavenging activity and chelating activity against Fe for the enzyme hydrolysates were more affected by the pH of enzyme hydrolysis than by their action temperature. DPPH-scavenging activity was higher at acidic pH than alkali pH, while chelating activity against Few was inversely affected. Hydrolysate of shrimp byproducts showed high antioxidative activities depending on the treatment condition, so the optimum treatment of enzymatic hydrolysate with Cryotin F and other proteases can be applied to shrimp byproducts (shells) and other protein sources for biofunctional ingredients.