• Korean Journal of Environmental Agriculture
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• v.22 no.2
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• pp.124-129
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• 2003

The objectives of this study are to manufacture an efficient $TiO_2$, photocatalyst and to delineate optimum operational parameters for TCE (trichloroethylene) degradation in a photocatalytic oxidative reactor. The $TiO_2$ photocatalyst irradiated by 365 nm UV light is expected to increase degradation of TCE in solution by a series of photocatalytic oxidations in the reactor. A new membrane $TiO_2$ photocatalyst wns eventually developed by coating a mixture of Davan-C(0.24 wt%) and PVA(0.16 wt%) on the surface of slips using the slip-casting method. Results show that increase in the number of coating of $TiO_2$ sol on surface of photocatalysts and in the surface thickness improved the endurance and photocatalysts, but these physical modifications caused significant decrease in the overall degradation efficiency of TCE. Pre-aeration or recirculation of the influents to the reactors containing TCE increased degradation efficiency of TCE. The optimum operational conditions far the surface area of photocatalysts and UV light intensity appeared to be $1.47\;mL/cm^2$ and $225\;W/cm^2{\times}100$, respectively, in the reactor. Based on the overall experimental results, the photocatalytic oxidation of TCE with the new membrane $TiO_2$ photocatalyst is found to be very effective under the operational conditions delineated in this study.

• Clean Technology
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• v.23 no.1
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• pp.54-63
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• 2017

Volatile organic compounds (VOCs) are widely used in both industrial and domestic activities. VOCs are one of the most unpleasant, frequently complaint-rousing factors of pollution around the world. It is now necessary to research and develop an alternative technology that could overcome the problems of the existing odor-control and VOC-eliminating techniques. In this study, essential oil and photocatalytic process was applied in the removal of benzene and toluene, typical VOCs in petrochemistry plant. therefore, this study conducted experiments on the selection of appropriate essential oil, photodegradation, hydroxyl radical generation capacity. The removal efficiency and reaction rate were performed to selecte the type and concentration of essential oil. As a result, removal efficiency of Hinoki Cypress oil was approximately 70% and reaction rate of Hinoki Cypress was high. The results of photolysis experiment, photocatalytic oxidation process showed that the decomposition efficiency of VOCs increased considerably with increasing UV lamp power. In addition, the conversion of VOCs was increased up to $0.1gL^{-1}$ photocatalysts. The hydroxyl radicals measure was performed to determine the ability to generate hydroxyl radicals. The analytical result showed that high $TiO_2$ concentration and lamp power was produced many hydroxyl radical. Experiments of the removal efficiency and reaction rate were performed using essential oil and photooxidation. As a result, the removal efficiency showed that the removal efficiency was increased high temperature and reaction time. The activation energy was calculated from the reaction rate equation at various temperature condition. Activation energy was approximately $18kJmol^{-1}$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.230-236
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• 2019

Recently, issues related to the quality of concrete have continuously resulted in surface quality problems, such as the exfoliation of concrete surfaces due to the cost reduction of cement and poor quality fine aggregate, scaling of surfaces caused by laitance, and plastic shrinkage cracks. Prompted by social issues, the application of a photo catalyst to road structures is being attempted to solve the environmental problems caused by fine dust and automobile exhaust. In this study, chemical admixtures were developed to improve the surface quality of concrete and to apply and distribute titanium dioxide in nanoscale sizes to provide basic data for the development of a photocatalyst-curing agent. As a result of the experiment, silicon and silane were reviewed as a raw material as a curing agent to develop a high performance curing agent with better film performance than conventional curing agents because they could form a film quickly on a fresh concrete surface. The distributed stability of the ultrasonic disperser showed the best performance through an outdoor test for four weeks to review the dispersion measures for the application of nanomaterials.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2002.05b
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• pp.279-280
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• 2002

$TiO_2$의 흡착에 의한 폐수처리는 거의 없으며, 본 실험의 T 산업 폐수에 평균 65mg/L 포함된 다량의 Cl￣ 이온은 광산화 반응의 억제제(inhibitor)로서 작용하는 것으로 사료되었다. 암모니아성 질소가 초기 40 mg/L에서 운전시간 24 시간 후에는 60 mg/L까지 증가함을 알 수 있었으며, 질산성 질소의 농도는 15 mg/L 까지 증가하였다. ${PO_4}^{3-}$ 의 농도 변화는 거의 없었으며 1 mg/L 이하의 낮은 농도로 존재하였으며, 무기탄소 양은 매우 소량으로 거의 변화가 없었다. 운전기간 동안 pH 2.4 ～ 2.6으로 수렴하였고 반응속도의 변화는 거의 없었으며, CODcr에 대한 $BOD_{5}$의 분율은 반응이 진행될수록 증가하는 것으로 보아 난분해성의 폐수가 광촉매 반응 후 생물학적 처리가 가능한 폐수로 변화되었음을 알 수 있었다.

• Proceedings of the KAIS Fall Conference
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• 2009.05a
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• pp.874-877
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• 2009

본 연구에서는 수용액 내의 오염물질 분해를 위하여 개발한 광촉매가 코팅된 실리카 비드의 광분 해반응 사용에 따른 활성저하 문제를 해결하기 위하여 반응에 사용한 비드의 활성을 향상시킬 수 있는 재생 방법에 관한 실험을 수행하였다. 비드의 재생방법으로 표면 세정법을 선택하였으며, 세정액으로는 물(증류수), 계면활성제, 아세톤 등 세정력이 서로 다른 3종의 용액을 사용하였다. 재생 과정은 서로 다른 3종의 세정액으로 반응에 사용하여 활성이 떨어진 비드를 세정한 후, 소성온도를 $100^{\circ}C$, $200^{\circ}C$, $300^{\circ}C$로 달리하여 30분간 처리하였다. 재생 처리과정은 각 1~3회 반복 수행하였으며, 서로 다른 조건에서 재생된 비드의 활성은 수용액 내의 methylene blue 광분해율로 측정하였다. 연구결과, 재생한 비드의 활성은 아세톤으로 세정한 후, $100^{\circ}C$에서 30분간 소성하였을 때 가장 우수한 것으로 나타났으며, 이러한 기초 연구결과를 토대로 현재보다 효율적인 재생 기술에 관한 연구를 수행 중에 있다.

• Applied Chemistry for Engineering
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• v.19 no.6
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• pp.674-679
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• 2008

$TiO_2$ impregnated stainless steel fiber photocatalysts ($TiO_2/SSF$) were fabricated to overcome inherent problems of powdery $TiO_2$ photocatalysts in water treatment. Adhesion strength of the impregnated $TiO_2$ was examined using an ultrasonic-cleaner. Photocatalytic activity was evaluated through decomposition experiment of methylene blue and formic acid. Bactericidal efficiency was evaluated through sterilization experiment of E. Coli and Vibrio Vulnificus. Adhesion strength of the impregnated $TiO_2$ was so high that more than 95% was left over even after the treatment in an ultrasonic-cleaner for 30 min. Methylene blue and formic acid were decomposed as much as 60% and 38% of the initial concentration and more than 99.9% of E. Coli and Vibrio Vulnificus were killed after 1 hour exposure to the prepared photocatalyst under UV irradiation. In the case of decomposition of formic acid, decomposition ratio increased if oxidants were added. Especially the decomposition ratio increased as high as 80% when hydrogen peroxide was added as an oxidant.

• KSBB Journal
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• v.23 no.1
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• pp.83-89
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• 2008

Food wastewater derived from the three-stage methane fermentation system developed in this lab contained high concentration organic substances. The organic wastewater should be treated through advanced wastewater treatment system to satisfy the "Permissible Pollutant Discharge Standard of Korea". In order to treat the organic wastewater efficiently, several optimum operation conditions of a modified $UV/TiO_{2}$ photocatalytic system have been investigated. In the first process, wastewater was pre-treated with $FeCl_{3}$. The optimum pH and coagulant concentration were 4.0 and 2000mg/L, respectively. Through this process, 52.6% of CODcr was removed. The second process was $UV-TiO_{2}$ photocatalytic reaction. The optimum operation conditions for the system were as follows: UV lamp wavelength, 254 nm; wastewater temperature, $40^{\circ}C$; pH 8.0; and air flow rate, 40L/min, respectively. Through the above two combined processes, 69.7% of T-N and 70.9% of CODcr contained in the wastewater were removed.

• Korean Chemical Engineering Research
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• v.54 no.2
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• pp.152-156
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• 2016

Experimental research on the preparation of photocatalyst for the decomposition of brilliant blue FCF ($C_{37}H_{31}O_9N_2S_3Na_2$) was performed. $TiO_2$ and ZnO powders were prepared from titanium (IV) sulfate and zinc acetate at low reaction temperature and atmospheric pressure by hydrothermal precipitation method without calcination. In addition, $TiO_2$ was prepared with cationic surfactant CTAB (Hexadecyltrimethyl ammonium bromide) at the same conditions. The physical properties of prepared $TiO_2$ and ZnO, such as crystallinity, average particle size and absorbance, were investigated by XRD, Zeta-potential meter and DRS. And, the photocatalytic degradation of brilliant blue FCF has been studied in the batch reactor under UV radiation. For the photocatalysts prepared without CTAB, $TiO_2$ has smaller particle size and larger absorbance and photocatalytic reaction rate than ZnO. And $TiO_2$, prepared with CTAB whose concentration is 1/10 of that of precursor, shows 15% higher than that prepared without CTAB in final photocatalytic degradation ratio of brilliant blue FCF.

• Analytical Science and Technology
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• v.11 no.1
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• pp.13-19
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• 1998

In the dye sensitization for the solar energy conversion with a photoelectrochemical cell containing allylthiourea, the time profile of the sensitized photocurrent showed a rise and fall with the irradiation time. The dye solution before and after irradiation was analyzed by means of spectroscopic methods. A new precipitation reaction between sensitizer and supersensitizer and photobleaching of the dye appeared to be involved in the decreased photocurrent.

• Applied Chemistry for Engineering
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• v.27 no.3
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• pp.307-312
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• 2016

Lead molybdate ($PbMoO_4$) was successfully synthesized using a facile surfactant-assisted hydrothermal process and characterized by XRD, Raman, TEM, PL, BET and DRS. We also investigated the photocatalytic activity of these materials for the decomposition of Rhodamine B under UV-light irradiation. From XRD and Raman results, well-crystallized $PbMoO_4$ crystals were successfully synthesized with the particle size of 52-69 nm. $PbMoO_4$ catalysts prepared in the presence of cetyltrimethyl ammonium bromide (CTAB) enhanced the photocatalytic activity compared to that of using P-25 and pure $PbMoO_4$ catalysts. The maximum photocatalytic activity of $PbMoO_4$ catalyst were observed when preparing it in pH 9 solution. The The PL peak at about 540 nm were observed for all catalysts and the excitonic PL signal increased proportionally with respect to the photocatalytic activity of Rhodamine B.