• Journal of Industrial Technology
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• 제31권B호
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• pp.119-125
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• 2011

N-doped Titanium oxides were prepared by using urea as a source of nitrogen. The photoactivities of the doped $TiO_2$ were evaluated on the basis of degradation of humic acid in aqueous solutions with different light sources, ultraviolet lamp, fluorescent lamp and solar light. XRD analysis was conducted to identify the crystal structure of the synthesized photocatalysts. N-doped $TiO_2$ and $pure-TiO_2$ was anatase type. SEM results showed that spherical particles were formed, which are the characteristics of the anatase form. N doped $TiO_2$ showed higher $UV_{254}$ decrease ratio and DOC removal ratio compared to $pure-TiO_2$. The humic acid degradation reaction using the UV-A lamp and UV-C lamp was assigned to pseudo-first order reaction. For solar light, only $pure-TiO_2$ and $N-TiO_2$ exhibited the pseudo-first order reaction.

• Journal of Korean Society of Environmental Engineers
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• 제27권9호
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• pp.1006-1015
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• 2005

We investigated the effect of hydroxyl radicals on the photolysis of triclosan (TCS), which is a potent broad-spectrum antimicrobial agent. TCS degradation during the initial reaction time of 5 min followed a pseudo-first order kinetic model ai all light intensities at a wavelength of 365 nm and at the low light intensities at a wavelength of 254 nm. The photodegradation rate significantly increased with decreasing wavelength and increasing the UV intensities. The activity of hydroxyl radicals was suppressed when methanol was used as the solvent instead of water. An increase in the photon effect was observed when the UV intensity was higher than $5.77{\times}10^{-5}$ einstein $L^{-1}min^{-1}$ at 254 nm, and lower than $1.56{\times}10^{-4}$ einstein $L^{-1}min^{-1}$ at 365 nm. The quantum yield efficiency for the photolysis of TCS was higher at 365 nm than at 254 nm among the above mentioned UV intensities. Dibenzodichloro-p-dioxin (DCDD) and dibenzo-p-dioxin were detected as intermediates at both UV intensities of $1.37{\times}10^{-4}$ and $1.56{\times}10^{-4}$ einstein $L^{-1}min^{-1}$ at 365 nm. Dichlorophenol and phenol were also detected in all cases. Based on our findings, we presented a possible mechanism of TCS photolysis.

• Journal of Industrial Technology
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• 제28권A호
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• pp.23-26
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• 2008

Ozone/GAC and ozone-GAC processes were introduced for treatment of humic acid, which is representative refractory organic compound. The treatment efficiencies of humic acid in each process were analyzed in pH variation, DOC removal, and $UV_{254}$ decrease. $UV_{254}$ decrease in all processes was comparatively high with efficiency over 92%. $UV_{254}$ decrease in ozone alone process was 85%. DOC removal in Ozone-GAC process was the highest with 75%. Removal by Ozone/GAC, Ozone alone processes were 71% and 33% respectively.

• Journal of Sensor Science and Technology
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• 제16권4호
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• pp.254-258
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• 2007

A novel cure sensor based on the side-polished single mode fiber has been proposed and demonstrated. Two different UV curable epoxies were used to verify the feasibility of the side-polished single mode fiber as a high sensitivity cure sensor. The volume change of the epoxy by UV curing results in a corresponding change of the refractive index. The sensor can be used to monitor the curing process, the refractive index variation and the volume change of epoxy in real time during the UV curing process. In addition, small birefringence of the epoxy film can be detected using the sensor.

• Applied Chemistry for Engineering
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• 제25권4호
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• pp.357-362
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• 2014

To prepare diketopyrrolopyrrole (DPP) red 254 pigment with high shield and bright color, DPP red 254 crude previously synthesized was treated at various thermal-treat temperature, addition derivative and ball-milling. The properties of samples were measured by the means of FT-IR, UV-Vis spectroscopy, TEM, PSA, BET surface area analyzer, viscometer and spectrophotometer. It was found that solvent thermal-treatment of the sample prepared after ball-milling as nano-scale was very effective method in pigmentation process.

• Journal of Pharmaceutical Investigation
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• 제26권2호
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• pp.83-89
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• 1996

A reverse-phase HPLC method to determine DL-Carnitine Hydrochloride in pharmaceutical preparation is described. UV absorption derivatives of DL-Carnitine Hydrochloride were formed with p-Bromophenacyl Bromide in an essentially quantitative manner using crown ether as catalyst. The DL-Carnitine-bromophenacyl ester absorbed UV radiation strongly at 254nm, allowing the detection of as small a quantity as 12.5ng of DL-Carnitine Hydrochloride. A linear defection range was $5\;{\times}\;10-8 \;{\sim}\;5\;{\times}\;10-7M$ of DL-Carnitine Hydrochloride. And the linear regression at various drug concentration was =0.999 (n=10). The DL-Carnitine Hydrochloride in pharmaceutical preparation was successfully derivatized and separated from other constituents by reverse phase HPLC with detection at 254 nm.

• Journal of Environmental Science International
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• 제9권2호
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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.

• Journal of Korean Society of Water and Wastewater
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• 제9권3호
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• pp.99-107
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• 1995

Various humic substances are widely distributed in natural water body, such as rivers and lakes and cause the yellowish or brownish color to water. The evidence that humic substances are precursors of THMs formation in chlorinated drinking water has been reported m the Jiteratures. For the reason of public health as well as aesthetics, needs for humic substances removal have been increased in the conventional water treatment processes. In this research, the characteristics of aluminium coagulation of humic acids and humic acids were investigated. The optimum pH and coagulants dosage to remove these materials simultaneously by coagulation were alto studied. The results are as followed; 1. UV-254 absorptiometry for measuring the concentration of aquatic humic acids showed good applicability and stable results. 2. The optimal pH range for humic acids removal by aluminium coagulation was 5 to 5.5, however, an increase in aluminium coagulant dosage could enhance the removal rate of humic acids in the wide pH range. 3. Coprecipitation of humic acids in the typical pH range of 6.5 to 8 in water treatment processes may require the sweep coagulation mechanism with the excess aluminium coagulant dosage. 4. Using PAC(poly aluminium chloride) or PASS(poly aluminium silica sulfate) as coagulants was able to expand the operating range for removing humic acids. 5. From the coagulation of humic substances(UV-254) and turbidity at pH range of 5.5 - 6.0 and alum dose of 86 ppm, the removal efficiency of turbidity from the reservoir water was above 90% and that of UV-254 was above 70%. 6. By using the reservoir water, the optimum condition of rapid mixing for simultaneous removal of turbidity and UV-254 absorbance was pH of 5.8 and LAS dose of 86 ppm, in this study.

• Analytical Science and Technology
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• 제13권2호
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• pp.241-249
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• 2000

In this paper, ozonation of humic acid in water was characterized using $UV_{254}$ absorbance, TOC, Ultra Filtration and $^{13}C-NMR$. Also, carbonyl compounds in ozonated water were analyzed by GC/MS using PFBOA method. Ozonation by-products of water containing humic acid were determined as formaldehyde, acetaldehyde, acetone, glyoxal and methylglyoxal. Results of $UV_{254}$ absorbance and TOC with ozonation time at humic acid 20, 100ppm represent that decrease rate of 80% within ozonation time is 20 min and TOC removal rate of 40-50% within ozonation time is 30 min. Results for $^{13}C-NMR$ and Ultra Filtration, humic acid of high molecular weight by ozonation are oxidated and decomposed so that it was conversed low molecular weight such as aldehydes, carboxylic acid.

• Membrane Journal
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• 제19권3호
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• pp.203-211
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• 2009

In this study, we used the hybrid module that was composed of granular activated carbons (GAC) packing between module inside and outside of tubular ceramic microfiltration membrane for advanced drinking water treatment. Instead of natural organic matters (NOM) and fine inorganic particles in natural water source, modified solution was prepared with humic acid and kaolin. $N_2$-back-flushing of 10 sec was performed per every period of 10 min to minimize membrane fouling and to improve permeate flux (J). As a result, resistance of membrane fouling ($R_f$) decreased and J increased as concentration of humic acid changed from 10 mg/L to 2 mg/L step by step, and finally the highest total permeate volume ($V_T$) could be obtained at 2 mg/L. Then, treatment efficiencies of turbidity and $UV_{254}$ absorbance were excellent above 99.36% and 97.19%, respectively, but that of $UV_{254}$ absorbance for only microfiltration without GAC at 10 mg/L of humic acid was decreased a little as 90.84%.