• The Korean Journal of Pesticide Science
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• v.2 no.2
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• pp.39-44
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• 1998

Three pesticides for paddy rice, iprobenfos, isoprothiolane, and diazinon were examined on some environmental factors, their hydrolysis, microbial degradation, and photolysis in aqueous systems. Iprobenfos was mainly degraded by microorganisms and its half-life was 5.7 days at $28^{\circ}C$ in aqueous systems. Hydrolysis of iprobenfos was accelerated by the higher temperature, but its photodegradation was accelerated by the lower pH. Isoprothiolane was rapidly decomposed by two factors, microorganisms and sunlight. The half-life of isoprothiolane by sunlight was 91 days at pH 9.0, while it was 13 days at pH 4.0 and 16 days at pH 7.2. However, it was shortened under low pH condition. In aqueous system, diazinon was degraded by all of three factors and its degradation rate was remarkably accelerated by acidic solution. Main degradation factors of iprobenfos, isoprothiolane, and diazinon in the aqueous system were investigated by microbial degradation, photolysis, and hydrolysis, respectively. The strains of microbial degradation for iprobenfos, isoprothiolane, and diazinon in the aqueous environment were identified as Pseudomonas putida, Alcaligenes xylosoxydans ss, Klebsiella planticola/ornithinllytica, respectively. The similarity rates of identity were $54.8{\sim}86.2%$ with biolog-system.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.1
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• pp.69-75
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• 2009

The characteristics of disinfection and organic removal were investigated with pulse UV lamp in this study. The intensity and emission wavelength of pulse UV Lamp were compared with low pressure UV lamp. The emission spectrum range of pulse UV lamp was between 200 and 400 nm while the emission spectrum of low pressure UV lamp was only single wavelength of 254nm. 3 Log inactivation rate of B. subtilis spore by pulse UV and low pressure UV irradiation was determined as $44.71mJ/cm^2$ and $57.7mJ/cm^2$, respectively. This results implied that wide range of emission spectrum is more effective compared to single wavelength emission at 254nm. 500ng/L of initial 2-MIB concentration was investigated on the removal efficiency by UV only and $UV/H_2O_2$ process. The removal efficiency of UV only process achieved approximately 80% at $8,600mJ/cm^2$ dose. 2-MIB removal rate of $UV/H_2O_2$ (5 mg/L $H_2O_2$) process was 25 times increased compared to UV only process. DOC removal efficiency for the water treatment plant effluent was examined. The removal efficiency of DOC by UV and $UV/H_2O_2$ was no more than 20%. Removal efficiency of THMFP(Trihalomethane Formation Potential), one of the chlorination disinfection by-products, is determined on the UV irradiation and $UV/H_2O_2$ process. Maximum removal efficiency of THMFP was approximately 23%. This result indicates that more stable chemical structures of NOM(Natural Organic Matter) than low molecule compounds such as 2-MIB, hydrogen peroxide and other pollutants affect low removal efficiency for UV photolysis. Consequently, pulse UV lamp is more efficient compared to low pressure lamp in terms of disinfection due to it's broad wavelength emission of UV. Additional effect of pulse UV is to take place the reactions of both direct photolysis to remove micro organics and disinfection simultaneously. It is also expected that hydrogen peroxide enable to enhance the oxidation efficiency on the pulse UV irradiation due to formation of OH radical.

• Environmental Engineering Research
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• v.23 no.1
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• pp.46-53
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• 2018

This study explores the environmentally innovative and low-impact technology, a zero food waste system (ZFWS) that utilizes food waste and converts it into composts or biofuels and curtails carbon emissions. The ZFWS not just achieves food waste reductions but recycles food waste into fertilizer. Based on a fermentation-extinction technique using bio wood chips, the ZFWS was employed in a field experiment of the system installed in a large-scale apartment complex, and the performance of the system was examined. The on-site ZFWS consisted of three primary parts: 1) a food waste slot into which food waste was injected; 2) a fermentation-extinction reactor where food waste was mixed with bio wood chips made up of complex enzyme and aseptic wood chips; and 3) deodorization equipment in which an ultraviolet and ozone photolysis method was employed. The field experiment showed that food waste injected into the ZFWS was reduced by 94%. Overall microbial activity of the food waste in the fermentation-extinction reactor was measured using adenosine tri-phosphate (ATP), and the degradation rate of organic compounds, referred to as volatile solids, increased with ATP concentration. The by-products generated from ZFWS comply with the national standard for organic fertilizer.

• Journal of the Korean Vacuum Society
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• v.7 no.s1
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• pp.20-24
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• 1998

Photploymer films are widely used in printing and electronic industries, and their usage is expanding to encompass holography, data storage and data processing, optical waveguides and compact disks, etc. One of widely used photoplymerization initiator, 20chloro-hexaarylbiimidazole (o-Cl-HABI), is studied by laser flash photolysis in dichloromethane solution in the absence and presence of the visible light photosensitizing dye, 2, 5-bis[(2, 3, 6, 7 -tetrahydro- 1H, 5H -benzo [i, j,] quinolizin -1-yl) methylene]-cyclopenta-none, (JAW). In the presence of JAW, an increase in triarylimidazolyl radicals L.formation is observed in relative to the absence of JAW. The mechanism of this photosensitizing dissociation is concluded as the dissociation of the o-Cl-HABI radical anion formed by the electron transfer from excited singlet state of JAW to o-Cl-HABI. The observed formation of L.radicals exhibits a linear dependence on o-Cl-HABI concentration. The rate constant of electron transfer obtained from this dependence is equal to (1.0$\pm$0.2) x $10^9 M^{-1}s^{-1}$. No reaction between the excited triplet state of JAW and o-Cl-HABI is found.

• Environmental Engineering Research
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• v.11 no.5
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• pp.241-249
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• 2006

A mathematical model is described for the prediction of convective upward transport of an organic solvent driven by evaporation at the surface, which is known as the major transport mechanism in the in-situ photolysis of a soil contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin(TCDD). A finite-element model was proposed to incorporate the effects of multiphase flow on the distribution of each fluid, gravity as a driving force, and the use of hysteretic models for more accurate description of k-S-p relations. Extensive numerical calculations were performed to study fluid flow through three types of soils under different water table conditions. Predictions of relative permeability-saturation-pressure (k-S-p) relations and fluids distribution for an illustrative soil indicate that hysteresis effects may be quite substantial. This result emphasizes the need to use hysteretic models in performing flow simulations including reversals of flow paths. Results of additional calculations accounting for hysteresis on the one-dimensional unsaturated soil columns show that gravity affects significantly on the flow of each fluid during gravity drainage, solvent injection, and evaporation, especially for highly permeable soils. The rate and duration of solvent injection also have a profound influence on the fluid saturation profile and the amount of evaporated solvent. Key factors influencing water drainage and solvent evaporation in soils also include hydraulic conductivity and water table configuration.

• The Korean Journal of Food And Nutrition
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• v.10 no.1
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• pp.6-13
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• 1997

Reactivity and reaction mechanism for the photosensitized generation of hydroxyl radical by various coumarin derivatives are investigated by means of ESR and laser flash photolysis methods. The nine kinds of coumarin derivatives show to be proceeded through the OH·radical generation mechanism, however 1-ethyl-3-nitro-1-nitrosoguanidine decomposes and produces the carbene intermediate before OH·radical generation reaction occurs. The nine coumarin derivatives show the signals, which are corresponded to DMPO-OH spin adducts. NaN3, EtOH and HCOONa act as a strong photosensitizer to quench OH·radical. The decay rate constants of the hydrated electrons in the case of added N2O show higher than added K3Fe(CN)6.

• Journal of the Korean Chemical Society
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• v.38 no.8
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• pp.598-602
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• 1994

Light-induced electron transfer reaction within binuclear complex $(NC)_5FeII-L-CoIII(NH_3)_5$ was studied with steady-state photolysis and the rate constants were measured for various bridging lignands. klight and quantum yields for BP, PHEN, DAP having conjugation between metal binding sites were about $3{\times}10^{-2} sec^{-1}$ and 1, and for BPEA having no conjugation were about $2{\times}10^{-4} sec^{-1}$ and 0.03. Light-induced electron transfer reaction within binuclear complex was proved to be the chemical mechanism which had charge transfer excited state MLCT*.

• Bulletin of the Korean Chemical Society
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• v.30 no.1
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• pp.177-182
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• 2009

We present the geminate rebinding kinetics measurements of CO to 2-methylimidazole (2-MeIm) bound ferrous protoporphyrin- IX (FePPIX) in alkaline glycerol/water mixtures at 293 K after photolysis. The kinetics was probed by monitoring the CO stretching mode using femtosecond vibrational spectroscopy. When 2-MeIm is used in excess, heme dimers that typically form in low viscosity solutions disappear as the viscosity of the solvent increases. Heme aggregates formed in low viscosity solutions turn monomeric as more 2-MeIm is added, suggesting that 6-coordinated heme, including a strong proximal histidine tends to be in the monomeric form. The vibrational band of CO in the 2-MeIM-FePPIX-CO is well described by a single Gaussian function centered at 1958 $cm^-1$ and 28 $cm^-1$ full width at half maximum. The efficiency and rate of the geminate rebinding of CO to the heme increase with viscosity of the solvent, suggesting that retention of the dissociated CO near the heme, for a longer period by the viscous solvent media, accelerates rebinding.

• Bulletin of the Korean Chemical Society
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• v.30 no.4
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• pp.913-916
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• 2009

Femtosecond vibrational spectroscopy was used to probe the dynamics of CO rebinding to hemoglobin (Hb), denatured by 4.0 M GdnHCl in $D_2O# at 283 K, after photolysis of HbCO. The stretching mode of $^{13}CO$ bound to the denatured $Hb^{13}CO$ showed a single band centered at 1922 $cm^{-1}$, indistinguishable from that of denatured $Mb^{13}CO$. Geminate rebinding of CO to the denatured Hb was accelerated more than 1000 times, suggesting that the native structure of the Hb is required to suppress efficient geminate rebinding of CO, as is the case in Mb. The geminate yield and rate for CO rebinding are almost the same in both the denatured Hb and Mb. Similarity in the equilibrium spectrum and rebinding dynamics of CO indicates that the state of the denatured Hb is very similar to that of the denatured Mb. In the denatured Hb, quaternary contact of the protein is likely severed, with the denatured protein existing as an independent subunit much like Mb.

• Journal of Korean Society for Atmospheric Environment
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• v.29 no.3
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• pp.307-316
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• 2013

The sensitivity of ozone to $NO_x$ and volatile organic compounds (VOCs) emission rates under different ventilation rates and $NO_2-to-NO_x$ emission ratios in a street canyon is investigated using a chemistry box model. The carbon bond mechanism IV (CBM-IV) with 36 gaseous species and 93 chemical reactions is incorporated. $NO_x$ and VOCs emission rates considered range from 0.01 to $0.30ppb\;s^{-1}$ with intervals of $0.01ppb\;s^{-1}$. Three different ventilation rates and three different $NO_2-to-NO_x$ emission ratios are considered. The simulation results show that the ozone concentration decreases with increasing $NO_x$ emission rate but increases with increasing VOCs emission rate. When the emission ratio of VOCs to $NO_x$ is smaller than about 4, the ozone concentration is lower in the street canyon than in the background. On average, the magnitude of the sensitivity of ozone to $NO_x$ emission rate is significantly larger than that to VOCs emission rate. As the $NO_x$ emission rate increases, the magnitude of the sensitivity of ozone to $NO_x$ and VOCs emission rates decreases. Because the ozone concentration is lower in the street canyon than in the background, the increased ventilation rate enhances ozone inflow from the background. Therefore, the increase in ventilation rate results in the increase in ozone concentration and the decrease in the magnitude of the sensitivity of ozone to $NO_x$ and VOCs emission rates when the emission ratio of VOCs to $NO_x$ is smaller than about 4. On the other hand, the increase in $NO_2-to-NO_x$ emission ratio results in the increase in ozone concentration because the chemical ozone production due to the $NO_2$ photolysis is enhanced. In the present experimental setup, the contribution of the change in $NO_2-to-NO_x$ emission ratio to the change in the sensitivity of ozone to $NO_x$ emission rate is larger than that of the change in ventilation rate.