In order to reuse the photocatalyst and enhance the photolysis efficiency, we have used atmospheric pressure dielectric barrier discharge (APDBD) to clean and activate TiO2 powder. The photocatalytic activity of the TiO2 powder before and after APDBD treatment was evaluated by the degradation of methylene blue (MB) in aqueous solution. The apparent reaction rate constant of photolysis of the first sample of reused TiO2 cleaned by APDBD improved to a level up to 0.32h- 1 higher than the 30 % value of the initial TiO2 powder. As the number of photolysis reactions and APDBD cleanings increased, the apparent rate constants gradually decreased; however, the fourth photolysis reaction still showed a value that was greater than 10% of the initial value. In addition, APDBD treatment enhanced the process by which TiO2 effectively adsorbed MB at every photolysis stage.

본 연구는 자외선 광분해에 의한 비스페놀 A (BPA)의 에 스트로겐 활성 저감에 미치는 하수처리장 방류수 유기물질 의 영향을 조사하였다. 방류수 유기물질과 표준으로 사용한 스와니강 자연 유기물질은 극성에 따라 소수성, 반친수성, 친수성 분획으로 분리하였다. 특이 자외선 흡수 (SUVA) 분 석 결과, 방류수 유기물질은 높는 소수성을 가지고 있는 자 연 유기물질과 다르게 소수성이 낮은 미생물 기원 유기물 질과 유사한 특성을 나타내었다. 3시간의 자외선 조사는 방 류수 및 자연 유기물질의 극성에 따라 SUVA 값을 유의하 게 감소시켰다 (p<0.0001). 유기물질이 없는 조건에서, BPA (5.0×10-5 M)의 상대 에스트로겐 활성도는 자외선 광분해 에 의해 86%에서 63%로 감소하였다. 그러나 유기물질이 있 는 조건에서 상대 에스트로겐 활성도는 평균적으로 68%에 서 37%로 감소하였으며, 유기물질의 종류 (방류수 또는 자연 유기물질) 및 극성 (소수성, 반친수성, 친수성)과 유의한 차이 를 나타내지 않았다 (p>0.05). 결과적으로, 유기물질이 있고 없는 조건에서 자외선 광분해에 의해 감소한 BPA의 상대 에스트로겐 활성도는 각각 31%와 23%였으며, 이것은 방류 수와 자연 유기물질 모두 광분해에 의한 BPA의 에스트로겐 활성 저감을 촉진시킨다는 것을 제시한다.

수출용 온실 단지로 기대되는 간척지의 광환경은 해무 등에 의해 내륙과는 다른 광환경 특성을 나타낸다. 이러한 간척지에서 온실 설계 기준을 작성하기 위해서 산란 광과 직달광을 고려한 온실 내 광분포 연구가 필요하다. 본 연구에서는 간척지의 고유의 광환경 특성을 분석하고 3-D 온실 모델에 적용하여 간척지의 온실 내 공간적인 광분포를 추정하고자 하였다. 먼저 간척지의 일사량을 산란광과 직달광으로 구분하여 측정하고 내륙의 일사량과 비교하였다. 또한 간척지 지역에 설치된 온실 내의 광분포를 측정하고 이를 시뮬레이션을 통해 계산된 값과 비교함으로써 3-D 온실 모델에 대한 검증을 실시하였다. 간척지는 내륙에 비하여 전체 일사량에 대비 높은 산란광의 비율을 나타내었으며, 특히 일출 및 일몰 부근에서 크게 나타났다. 3-D 온실 모델에 의한 온실 내 예측 광 분포는 실제 간척지의 온실 내 광분포와 유사하게 나타 났다. 검증된 3-D 온실 모델을 통하여 임의의 외부 광조 건에 대하여 간척지 지역의 온실 내부의 시간적인 평균 광도의 변화와 광분포를 예측할 수 있었다. 이러한 결과는 간척지 지역의 온실 내 광환경 해석 이외에도 작물의 수광량 해석에도 유용하게 활용될 것으로 예상된다.

xTiO2-ySiO2 system photocatalysts were developed by sol-gel method based on the change of production parameters, and their structure of crystallization and the specific surface area were measured. Considering the efficiency of the ethanol and phenol degradation using the catalyst, the conclusions were obtained as follows: By means of X-ray analysis of xTiO2-ySiO2 powder that is obtained from Titanium and Silicon alkoxide by sol-gel process, it is shown that crystal structure of anatase type is a dominating structure and, on the other hand, the structure of rutile also partly exists. The increase of SiO2 contents causes the decrease of the degree of crystallization of the gel, whereas the specific surface area preferentially increases. It is shown that more than 90% of ethanol and phenol are degraded when reaction time is about three and an hours, and the maximum degradation rate of ethanol and phenol is shown in 60TiO2-40SiO2 catalyst.

The photocatalytic degradation of methylene blue(MB) was investigated using TiO2 as photocatalyst and UV radiation. TiO2 supported with activated carbon(AC) was prepared by SOL-GEL method and depended on several parameters such as the mass ratio of TiO2/AC, pH and experimental time. The presence of the anatase and rutile crystal phase was determined by XRD analyses of the prepared TiO2. The degradation of MB with TiO2/AC was about 20% higher than that of AC alone. A variation of photodegradation was negligible under UV radiation conditions ( ≥ 40W). It was experimentally showed that the photodegradation rate was increased with increasing the amount of photocatalyst. The optimal catalyst was prepared by impregmation of 5wt%-TiO2 with AC and was calcined at 300℃, and showed about 99% removal efficiency for 3hrs.

Dispersion stabilities and photocatalytic activities of rutile powders with unique nano-structure synthesized by homogeneous precipitation process at low temperature(HPPLT) have been investigated in the acrylic resin containing fluorostyrene in the range of mole. Isoelectric point of in the acrylic resin placed in the neutral region whereas that of in the water placed in the acidic region, indicating that zeta potential and agglomeration of powder is strongly dependent on the pH and the type of solvent. To prepare an adhesion, an acrylic resin containing fluorostyrene was synthesized by a radical polymerization. The adhesion of coating layer was increased with increasing fluorostyrene's contents without changing the dispersion stabilities and degrading photocatalytic properties

An aqueous solution of a commercial liquid synthetic detergent for kitchen use was photodecomposed in the presence of titanium dioxides powder under an atmosphere of air at room temperature. Titanium dioxides were prepared by sol-gel method from titanium iso-propoxide at different R ratio(H2O/titanium iso-propoxide) and calcined at 500℃. All titanium dioxides were characterized by XRD, BET surface area analyzer and UV-VIS spectrometer. The surface area of titanium dioxides prepared at R ratio=6 appeared higher volume about 20% than commercial TiO2 catalysts. XRD patterns of titania particles were observed mixing phase together with rutile and anatase type. Titanium dioxides prepared by sol-gel method show higher activity about 6% than commercial TiO2 catalysts on the photocatalytic degradation of a commercial liquid synthetic detergent for kitchen. The concentration of the detergent decreased to about 90% of its initial value at illumination times of 2 hour. Illumination for 30 minutes decreased the concentration of oxygen to about one-fifth of the initial value.

Piperophos에 대한 광분해 실험을 수행하여 속도상수와 분해생성물을 측정하였다. 햇빛을 이용한 광분해 실험은 2003년 10월 3일부터 10월 22일 까지 하였으며 상당기간 동안 농약이 햇빛에 안정함을 확인할 수 있었고, humic acid 의 광관여 효과가 없음을 알 수 있었다. 자외선을 이용한 광분해 실험에서 piperophos는 자외선을 단독조사하였을 때 자외선의 세기가 클수록 상대적으로 빠르게 분해되었으며, 광분해 촉매제인 TiO₂의 양을 증가시켜도 별 차이가 없었다. 광분해에 의한 분해산물을 확인하고자 GC/MS분석을 한 결과 piperophos의 분해생성물은 m/z=166의 0.0-dipropyl phosphorodithioate로 추정된다.

The propagation of light radiation in a turbid medium is an important problem that confronts dosimetry of therapeutic laser delivery and the development of diagnostic spectroscopy. Scattered light is measured as a function of the position(distance r, depth z) between the axis of the incident beam and the detection spot. Turbid sample yields a very forward-directed scattering pattern at short range of position from source to detector, whereas the thicker samples greatly attenuated the on-axis intensity at long range of position. The portions of scattered light reflected from or transmitted throughphantom depend upon internal reflectance and absorption properties of the phantom. Monte Carlo simulation method for modelling light transport in tissue is applied. It uses the photon is moved a distance where it may be scattered, absorbed, propagated, internally reflected, or transmitted out of tissue. The photon is repeatedly moved until it either escape from or is absorbed by the phantom. In order to obtain an optimum therapeutic ratio in phantom material, optimum control the light energy fluence rate is essential. This study is to discuss the physical mechanisms determining the actual light dose in phantom. Permitting a qualitative understanding of the measurements. It may also aid in designing the best model for laser medicine and application of medical engineering.

This study provides a simple introduction to photo-catalyst technology to self-clean the organic dirts and degrade the air pollution in urban environment. Moreover, it shows the spray coating technique was applied to effective coating on the surface of concrete specimen by using as-developed integral photocatalyst solution. In order to examine photo-catalytic activity and degradation effectiveness on the surface of the concrete specimen, the UV-LED lamp was used as a light source to activate the photo-catalysis. Methyl-orange dye was used as an indicating method to speculate the photo-catalytic reaction and UV-VIS spectrometer to determine the molar content of the organic dye.

In this study, a metal-organic framework (MOF) material NH2-MIL-101(Fe) was synthesized using the solvothermal method, and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-visible spectrophotometry, field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and surface area measurements. The XRD pattern of the synthesized NH2-MIL-101(Fe) was similar to the previously reported patterns of MIL-101 type materials, which indicated the successful synthesis of NH2-MIL-101(Fe). The FT-IR spectrum showed the molecular structure and functional groups of the synthesized NH2-MIL-101(Fe). The UV-visible absorbance spectrum indicated that the synthesized material could be activated as a photocatalyst under visible light irradiation. FE-SEM and TEM images showed the formation of hexagonal microspindle structures in the synthesized NH2-MIL-101(Fe). Furthermore, the EDS spectrum indicated that the synthesized material consisted of Fe, N, O, and C elements. The synthesized NH2-MIL-101(Fe) was then employed as an adsorbent and photocatalyst for the removal of Indigo carmine and Rhodamine B from aqueous solutions. The initial 30 min of adsorption for Indigo carmine and Rhodamine B without light irradiation achieved removal efficiencies of 83.6% and 70.7%, respectively. The removal efficiencies thereafter gradually increased with visible light irradiation for 180 min, and the overall removal efficiencies for Indigo carmine and Rhodamine B were 94.2% and 83.5%, respectively. These results indicate that the synthesized MOF material can be effectively applied as an adsorbent and photocatalyst for the removal of dyes.

The characteristics of photocatalytic degradation of tar colorants such as brilliant blue FCF(BBF) and tartrazine(TTZ) with zinc oxide suspension was studied in a batch reactor under irradiation of ultra-violet ray. Photocatalytic degradation of TTZ with ZnO was more higher than that of BBF, and was increased with dosage of ZnO below 5g, but was nearly affected with initial pH of two tar colorants aqueous solution. Ammonium persulfate was more effective oxidant than potassium bromate which slightly increased the degradation of BBF, but not increased the degradation of TTZ. The photocatalytic degradation rates of BBF and TTZ were pseudo-first order with rate constants of 0.0066, 0.0092 and 0.015min-1 for BBF, 0.042, 0.077 and 0.110min-1 for TTZ at the dosage of 1, 2 and 5g ZnO, respectively.

Photodegradation of endosulfan alpha, beta, and sulfate known as the most toxic substance among organochlorine pesticides by UV irradiation was studied at experimental conditions such as different pH aqueous solution and reaction time. The initial concentration of endosulfan alpha, beta, and sulfate in aqueous solution was 500 ppb, respectively. The experiment of photodegradation was conducted in a quartz reactor equipped with a low pressure mercury lamp (100 W, 240 nm). The samples were withdrawn from the photo reactor at intervals of 0, 10 min, 30 min, 1 hr, 2 hr, and 4 hr. Endosulfan sulfate was never hydrolyzed and photodegraded in wide range of pH. At pH 5 and reaction time (240 min), endosulfan alpha was photodegraded up to 67%. Both endosulfan alpha and beta were started to photodegrade at pH 6.5 with the lapse of time, resulting in approximately 99.9% and 87.2% of photodegradation efficiency, respectively. Furthermore, at pH 9, endosulfan alpha and beta was partially hydrolyzed and photodegraded to 99.5% at 120 min of reaction time. During the photolysis, any photo-products of endosulfan alpha, beta, and sulfate were not observed.

This study aimed at improving the TiO2 photocatalytic degradation of HA. ·In this study, the Degradation of Humic Acid using Jeju Scoria Coated with WO3/TiO2 in the presence of UV irradiation was investigated as a function of different experimental condition : photocatalyst dosage, Ca2+ and HCO3- addition and pH of the solution. Photodegradation efficiency increased with increasing photocatalyst dosage, the optimum catalyst dosage is 2.5 g/L and Photodegradation efficiency is maximized to WO3/TiO2=3/7. This indicates that WO3 retains a much higher Lewis surface acidity than TiO2, and WO3 has a higher affinity for chemical species having unpaired electrons. The addtion of cation(Ca2+) in water increased the photodegradaion efficiency. But the addtion of HCO3- ion in water decreased a photodegradation efficiency. Photodegradation efficiency increased with decreasing pH. At pH < pzc, the electrostatic repulsion between the HA and the surface of TiO2 decreased.