• The Korean Journal of Pesticide Science
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• v.3 no.3
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• pp.20-26
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• 1999

This study was to investigate the potential degradation of a herbicide paraquat by Fenton reagents(ferric ion and hydrogen peroxide) under UV light irradiation(365 nm) in an aqueous solution. When $10{\sim}500$ mg/L of paraquat was reacted with either ferric ion or hydrogen peroxide in the dark or under UV light, no degradation was occurred. However, the simultaneous application of both ferric ion(0.8 mM) and hydrogen peroxide(0.140 M) in paraquat solution(500 mg/L) caused dramatic degradation of paraquat both in the dark (approximately 78%) and under UV light(approximately 90%). The reaction approached an equilibrium state in 10 hours. In the dark, when $0.2{\sim}0.8$ mM ferric ion was added, $20{\sim}70%$ paraquat of $10{\sim}500$ mg/L was degraded, regardless of hydrogen peroxide concentrations($0.035{\sim}0.140$ M), while under UV light, 95% of 10 and 100 mg/L paraquat was degraded regardless of ferric ion and hydrogen peroxide concentrations. At paraquat concentration of 200 and 500 mg/L, paraquat degradation increased with increasing ferric ion concentrations as in the dark. However the increase in hydrogen peroxide concentration did not affect the extent of paraquat degradation. The initial reaction rate constants(k) for paraquat degradation ranged from 0.0004 to 0.0314, and 0.0023 to 0.0367 in the dark and under UV light, respectively. The initial reaction rate constant increased in proportion to the increase in ferric ion concentration in both conditions. The half-lives of paraquat degradation(t1/2) were 20 - 1,980 and 19 - 303 minutes in the dark and under UV light, respectively. This study indicates that Fenton reagents under UV light irradiation are more potent than in the dark in terms of herbicide paraquat degradation in an aqueous solution.

• Korean Journal of Environmental Agriculture
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• v.1 no.1
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• pp.65-70
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• 1982

This experiment was conducted to see the effect of repeated application of IBP granular formulation(17%, 0,0-diisopropyl-S-benzyl thiophosphate) on the biodegradation of IBP and diazinon〔0,0-diethyl 0-(2-isopropyl-4-methyl-5-pyrimidinyl) phosphorothioate〕 in silt loam soil with 2.1% organic matter under flooded condition. The persistence of IBP in the soil was shortened by increasing the frequencies of application of the chemical. Enhanced degradation ability in the soil caused by repeated application of IBP was prolonged about 53 days, while the ability did not influence diazinon persistence in the soil. The half-lives of IBP in sterilized soil autoclaved at $121^{\circ}C$ for 30 minutes were about 3 times longer than those in viable soil, suggesting that microbial process was a major factor for IBP degradation in the soil. The total colony number of soil microbes showed little difference between the soils with and without repeated application of IBP. A possible concern of specific soil microorganisms on the pesticide degradation in soil was discussed.

• The Korean Journal of Pesticide Science
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• v.9 no.1
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• pp.60-69
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• 2005

The herbicide molinate has been detected with high frequency in the main river during the growing season in Korea. To elucidate the exposure of molinate in agricultural environment, the persistence and the degradation characteristics of molinate were investigated in paddy ecosystems. The half-lives of molinate were 4.1 days with soil aquatic system, and 4.2 days in only aquatic system. Initial dissipation rate of molinate in water was greater with soil aquatic system than that of only aquatic system. Photolysis of molinate was occurred about 31.0% of molinate treated in pure water, when irradiated at 5,530 $J/cm^2$ by the xenon lamp, but its hydrolysis was stable. For the accelerated photolysis of molinate in aqueous solution, several photosensitizers were screened, showing that the hydroperoxide($H_2O_2$) and acetone were prominent among the chemical tested. When hydroperoxide and zinkoxide(ZnO) were used as photosensitizer, their photolysis were accelerated greater than 98% and 58% in aqueous solution, respectively. Elution rate of molinate as granular formulations in aqueous system was more than 90% in 30 hour at $35^{\circ}C$. Molinate concentration pattern in paddy water was rapidly decrease from treatment till 7 days in paddy rice field and its half-lives were 3.7 days($Y=1.9258{\times}e^{-0.1865X}$(r=-0.9402)).

• Korean Journal of Environmental Agriculture
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• v.23 no.1
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• pp.47-51
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• 2004

In order to know the residual pattern of pesticides and predict to the degradation period until below MRL we experimented procymidone and chlorothalonil for grape which were the most detected pesticide in grape by NAQS(National Agricultural product Quality management Service) survey. In this experiment we sprayed those pesticides 10 days before harvest and analyzed 0, 1, 2, 3, 5, 7, 10 day sample to establish logical equation and to calculate $DT_{50}$. Also the same day samples stored at $4^{\circ}C$ and $20^{\circ}C$, which were compared their degradation patterns. During the cultivating period, the residue amount of procymidone was changed from 1.85 mg/kg (0 day) to 0.33 mg/kg (10 day), $DT_{50}$ was 3.5 days, and chlorothalonil was changed from 5.5 mg/kg (0 day) to 3.49 mg/kg (10 day), $DT_{50}$ was 4.4 days. During the storage period, $DT_{50}$ of procymidone and chlorothalonil at $4^{\circ}C$ were 10.5 and 7.6 days, and 6.3 and 6.1 days at $20^{\circ}C$, respectively.

• Advances in nano research
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• v.13 no.6
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• pp.527-543
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• 2022

A novel, green, versatile and magnetically retrievable BiFeO₃/CDR (Bismuth ferrite/coriander) nanocomposites were fabricated via simple wet chemical method utilizing in situ functionalized, cheap coriander seed powder (CDR 5%, 10%, 15% and 20 wt%) as a fuel to enhance the efficiency of pristine BiFeO₃. A comparative study was performed between BiFeO₃/CDR and BiFeO₃/CNT (Bismuth ferrite/carbon nanotubes) nanocomposites for the removal of various hazardous pollutants from waste water. The successful synthesis of the fabricated nanomaterials was monitored via FT-IR, Powder XRD, FE-SEM, CV, VSM, CHNS/O and XPS studies. The synthesized nanomaterials were employed for the oxidative degradation of Carbol fuchsin, Reactive black 5, Ciprofloxacin and Doxorubicin; adsorption of a pesticide malathion; and reduction studies for Para-nitrophenol (PNP). The fabricated nanomaterials (BiFeO₃/CDR) showcased excellent efficiency and comparable results with (BiFeO₃/CNT) for the removal of model pollutants. Moreover, synthesized green heterojunction was also testified for mixture of textile and pharmaceutical waste. Hence CDR can be utilized as a better alternative of CNTs.

• Korean Journal of Environmental Agriculture
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• v.3 no.2
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• pp.1-8
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• 1984

The present study was performed to elucidate pesticide residues in paddy rice applied with different application schedules and frequencies of pesticide formulations. Pungsanbyeo($Japonica{\times}Indica hybrid$) of rice(Oryza sativa L.) was chosen as target crop. Isoprothiolane(diisopropyl-l,3-dithiolan-2-ylidene malonate) 40EC (emulsifiable concentrates), 12G (granular), and chlorpyriphosmethyl [0,0-dimethyl 0-(3,5,6-trichloro-2-pyridyl) phosphorothioate] 25EC, 3G were selected as pesticide formulations. The closer the isoprothiolane EC application to harvest, the higher the residues in rice straw retained at harvest; however the G application on 30 days before harvest resulted in highest residue. Chlorpyriphosmethyl residues were higher as it was applied nearby to harvest. Degradation rate of chlorpyriphos-methyl in husked rice was quite similar to in rice straw, on the other hand isoprothiolane in the rice was more stable than that in rice straw. Translocated amount of applied G formulation to husked rice was meager irrespective to the chemicals. Percent reduction of isoprothiolane residues in husked rice by polishing was not related to application frequencies but to application date before harvest. Residual portions in rice straw, husked rice and polished rice of total input amount during rice cultivation were ranged from 0.19% to 0.99%, 0.01% to 0.48%, and 0.15%, respectively.

• Korean Journal of Food Science and Technology
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• v.32 no.2
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• pp.277-283
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• 2000

This study was conducted to investigate the effect of ozone treatment on the growth and pesticide-residual contents of soybean sprouts during cultivation. Total weight and length of the soybean sprouts treated by 0.3 ppm ozone water for 30min during soaking of soybean increased 27% and 19% higher than those of control group, respectively. But 27% of root weight decreased. No major differences in growth state were observed between the treatments during soaking and watering with ozone water, and watering with ozone water. Pesticide residues in soybeans treated with carbendazim, captain, diazinon, fenthim, dichlorvos and chlorpyrifos ranged from 4.75 to 8.35 ppm. The pesticides in soybean sprouts by the treatment of soaking and watering with water for 5 days, those by 0.3 ppm ozone-water watering, and those by soaking and watering with 0.3 ppm ozone water were destroyed to $85{\sim}99$, $89{\sim}100$ and $94{\sim}100%$, respectively. The order of degradation ratio in the pesticides was captan>dichlorvos>fenthion>carbendazin>diazinon>chlorpyrifos.

• Journal of Environmental Science International
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• v.9 no.2
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• pp.151-158
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• 2000

Considerable interest has been shown in recent years towards utilizing $TiO_2$ particles as a photocatalyst in the degradation of harmful organic contaminants. In this study, photocatalytic degradation of diazinon which is extensively used as a pesticide in the agriculture field, has been investigated with UV-illuminated $TiO_2$ weight, UV wavelength, pH of the solution. Photodegradation rate increased with decreasing initial concentration of diazinon and with increasing pH of the solution. Photodegradation rate increased with increasing $TiO_2$ weight, but was nearly the same at $TiO_2$ weight of 1g/$\ell$, 2 g/$\ell$, i.e., for initial diazinon concentratin of 5 mg/$\ell$. UV wavelength affecting on the degradation rate of diazinon decreased in the order of 254 nm>312 nm> 365 nm. For $TiO_2$ weight of 1 g/$\ell$and initial diazinon concentration of 5 mg/$\ell$, the photodegradation removal of diazinon was 100% after 130 min in the case of 254 nm, but 95% in the case of 312 nm, and 84% in the case of 365nm, after 180 min. The photodegradation of diazinon followed a first order or a pseudo - first order reaction rate. For initial diazinon concentration of 5 mg/$\ell$, the rate constants(k) in UV and $TiO_2$(1 g/$\ell$)/UV system were $0.006 min^{-1} and 0.0252 min^{-1} at 254 nm, 0.0055 min^{-1} and 0.0104 min^{-1} at 312 nm, and 0.004 min^{-1}$ at 365 nm respectively.

• KSBB Journal
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• v.9 no.5
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• pp.469-474
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• 1994

The purpose of the work was to evaluate the feasibility of a biological treatment process for the phenoxy alkanoic herbicide 2,4-D(2,4-dichlorophenoxyacetic acid) as a commercial pesticide. The phenoxy herbicide was 2,4-D amine salts which contained 40%(vol/vol) 2,4-D and 60%(vol/vol) solvent. A microbial consortium has been derived by enrichment with 2,4-D. The consortium utilized 2,4-D as the sole source of carbon and energy. Optimal pH on the 2,4-D degradation was 7.0 in this experiment. As concentrations of 2,4-D were increased, the degradation by microbial consontium became inhibited. The amendment with yeast extract and ascorbic acid accelerated the degradation of 2,4-D. High performance liquid chromatography methodology was used to measure 2,4-D and it also resolved 2,4-DCP(2,4-dichlorophenol), the corresponding phenol as intermediate. Gas chromatography-mass spectrometry was used for preliminary identification of the intermediate 2,4-DCP. UV scans of spent cultures showed that the maximum absorption of 2,4-D at the wavelength of 283 nm was decreased toward the end of incubation, but the consortium displayed no detectable spectral changes or peak shifts in the UV absorbance.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.6
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• pp.436-440
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• 2000

Recently, we reported an improved technology for the degradation of organophosphate nerve agents using whole cells of genetically engineered Escherichia coli that anchored and displayed the enzyme organophosphorus hydrolase on the cell surface. In this paper we report the immobilization of these cells on highly porous sintered glass beads and the subsequent application of the immobilized cell in a continuous-flow packed bed bioreactor for the biodetoxification of a widely used insecticide, coumaphos.