PURPOSES : The purpose of this study was to analyze the effect of reducing nitrogen oxide concentration in a photocatalyst (titanium dioxide) using statistical methods such as the Anderson-Darling test. METHODS : To compare and analyze the effect of reducing the nitrogen oxide concentrations in titanium dioxide, titanium dioxide was applied to the public road, and data acquisition in terms of nitrogen oxide concentration was conducted from roads with/without applying titanium dioxide (test section and reference section, respectively). Then, the probabilities of occurrence of nitrogen oxide concentrations in the test and reference sections were estimated and compared using the Anderson-Darling test. RESULTS : According to the comparison and analysis of probabilities in the nitrogen oxide concentration of the test and reference sections, the probabilities of nitrogen oxide concentration on December 4th were estimated as ‘High’ (17.5%, 37.9%), ‘Moderate’ (30.5%, 40.8%), and ‘Low’ (52.0%, 21.3%), respectively, and on December 5th, as ‘High’ (20.6%, 39.1%), ‘Moderate’ (26.2%, 33.0%), and ‘Low’ (53.2%, 27.9%), respectively. In addition, the probabilities of nitrogen oxide concentration in the test and reference sections were analyzed on December 6th as ‘High’ (16.5%, 36.8%), ‘Moderate’ (27.9%, 38.5%), and ‘Low’ (55.6%, 24.8%), respectively. CONCLUSIONS : Based on the results of this study, in the test section with application of titanium dioxide, the nitrogen oxide concentration was found to have a low probability, and in the reference section, the nitrogen oxide concentration was found to be higher than that in the test section. Therefore, it can be concluded that titanium dioxide applied to road facilities has a nitrogen oxide reduction effect.

광촉매는 물에서 유기 염료를 분해하는 친환경적 기술이다. 산화 텅스텐은 이산화 티타늄에 비해 더 작은 밴드갭을 지니고 있어 광촉매 나노물질로서 활발히 연구되고 있다. 계층적 구조의 합성, 백금 도핑, 나노 복합물 또는 다른 반도체 와의 결합 등이 광촉매 분해 효율을 향상시키는 방법들로 연구되고 있다. 이들 방법들은 광 파장의 적색편이를 유도하여 전자 이동, 전자-정공 쌍의 형성과 재결합에 영향을 미친다. 산화 텅스텐의 형태 개질을 통해 앞서 언급한 광촉매 분해 효율을 향상시키는 방법들과 합성에 대해 분석하였으며 금속 산화물과 탄소 복합재를 결합하는 방법이 새로운 물질의 합성이 필요 없으며 가장 효율적인 방법으로 조사되었다. 이러한 광촉매 기술은 수처리 분리막기술과 모듈화하여 정수처리 목적으로 사용 될 수 있다.

A heterogeneous photocatalytic system is attracting much interest for water and air purification because of its reusability and economical advantage. Electrospun nanofibers are also receiving immense attention for efficient photocatalysts due to their ultra-high specific surface areas and aspect ratios. In this study, ZnO nanofibers with average diameters of 71, 151 and 168 nm are successfully synthesized by facile electrospinning and a subsequent calcination process at 500 ℃ for 3 h. Their crystal structures, morphology features and optical properties are systematically characterized by X-ray diffraction, scanning electron microscopy, UV-Vis and photoluminescence spectroscopies. The photocatalytic activities of the ZnO nanofibers are evaluated by the photodegradation of a rhodamine B aqueous solution. The results reveal that the diameter of the nanofiber, controlled by changing the polymer content in the precursor solution, plays an important role in the photocatalytic activities of the synthesized ZnO nanofibers.

금속산화물 반도체 중 하나인 산화아연은 인체에 무해하고 친환경적이며, 우수한 화학적, 열 적 안정성의 특성을 지니며 3.37 eV의 넓은 밴드갭 에너지와 60 meV의 높은 엑시톤 바인딩 에너지로 인해 태양전지, 염료페기물의 분해, 가스센서 등 다양한 분야에 응용이 가능한 물질이다. 산화아연은 입 자 형상 및 결정성의 변화에 따라 광촉매 활성이 변하게 된다. 따라서, 다양한 실험변수와 첨가제를 사 용하여 입자를 합성하는 것이 매우 중요하다. 본 논문에서는 마이크로파 수열합성법을 사용하여 산화아연을 합성하였다. 전구체로는 질산아연을 사 용하였고, 수산화나트륨을 사용하여 용액의 pH를 11로 조정하였다. 첨가제로는 계면활성제인 에탄올아 민, 세틸트리메틸암모늄브로마이드, 소듐도데실설페이트, 솔비탄모노올레이트를 첨가하였다. 합성된 입자 는 별모양, 원추형, 씨드형태, 박막형태의 구형의 형상을 보였다. 합성된 산화아연의 물리・화학적 특성 은 XRD, SEM, TGA을 통하여 확인하였고, 광학적 특성은 UV-vis spectroscopy, PL spectroscopy, Raman spectroscopy으로 확인하였다.

PURPOSES: In areas of high traffic volume, such as expressway across large cities, the amount of nitrogen oxides (NOx) emitted into the atmosphere as air pollution can be significant since NOx gases are the major cause of smog and acid rain. Recently, the importance of NOx removal has arisen in the world. Titanium dioxide (TiO2), that is one of photocatalytic reaction material, is very efficient for removing NOx. The NOx removing mechanism of TiO2 is the reaction of solar photocatalysis. Therefore, TiO2 in road structure concrete need to be contacted with ultraviolet rays (UV) to be activated. In general, TiO2 concretes are produced by replacement of TiO2 as a part of concrete binder. However, considerable portion of TiO2 in concrete cannot contact with the pollutant in the air and UV. Therefore, TiO2 penetration method using the surface penetration agents is attempted as an alternative in order to locate TiO2 to the surface of concrete structure. METHODS: This study aimed to evaluate the NOx removal efficiency of photocatalytic concrete due to various TiO2 application method such as mix with TiO2, surface spray(TiO2 penetration method) on hardened concrete and fresh concrete using surface penetration agents. The NOx removal efficiency of TiO2 concrete was confirmed by NOx Analyzing System based on the specification of ISO 22197-1. RESULTS: The NOx removal efficiency of mix with TiO2 increased from 11 to 25% with increasing of replacement ratio from 3 to 7%. In case of surface spray on hardened concrete, the NOx removal efficiency was about 50% due to application amount of TiO2 with surface penetration agents as 300, 500 and 700g/m2. The NOx removal efficiency of surface spray on fresh concrete due to all experimental conditions, on the other hand, which was very low within 10%. CONCLUSIONS: It was known that the TiO2 penetration method as surface spray on hardened concrete was a good alternative in order to remove the NOx gases for concrete road structures.

To compare the photocatalytic performances of titania for purification of waste water according to applied voltages and doping, TiO2 films were prepared in a 1.0 M H2SO4 solution containing NH4F at different anodic voltages. Chemical bonding states of F-N-codoped TiO2 were analyzed using surface X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of the co-doped TiO2 films was analyzed by the degradation of aniline blue solution. Nanotubes were formed with thicknesses of 200-300 nm for the films anodized at 30 V, but porous morphology was generated with pores of 1-2 μm for the TiO2 anodized at 180 V. The phenomenon of spark discharge was initiated at about 98 V due to the breakdown of the oxide films in both solutions. XPS analysis revealed the spectra of F1s at 684.3 eV and N1s at 399.8 eV for the TiO2 anodized in the H2SO4-NH4F solution at 180 V, suggesting the incorporation of F and N species during anodization. Dye removal rates for the pure TiO2 anodized at 30 V and 180 V were found to be 14.0% and 38.9%, respectively, in the photocatalytic degradation test of the aniline blue solution for 200 min irradiation; the rates for the F-N-codoped TiO2 anodized at 30 V and 180 V were found to be 21.2% and 65.6%, respectively. From the results of diffuse reflectance absorption spectroscopy (DRS), it was found that the absorption edge of the F-N-codoped TiO2 films shifted toward the visible light region up to 412 nm, indicating that the photocatalytic activity of TiO2 is improved by appropriate doping of F and N by the addition of NH4F.

was successfully formed on a Ti specimen by MAO (Micro-Arc-Oxidation) method treated in electrolyte. This study deals with the influence of voltage and working time on the change of surface microstructure and phase composition. Voltage affected the forming rate of the oxidized layer and surface microstructure where, a low voltage led to a high surface roughness, more holes and a thin oxidized layer. On the other hand, a high voltage led to more dense surface structure, wider surface holes, a thick layer and fewer holes. Higher voltage increases photocatalytic activity because of better crystallization of the oxidized layer and good phase composition with anatase and rutile , which is able to effectively separate excited electrons and holes at the surface.

the less-reported gaseous studies have primarily dealt with chemical process stream concentrations than indoor air quality (IAQ) concentration levels. Accordingly, the current study was conducted to establish the feasibility of applying visible-light-induced TiO₂ doped with sulfur (S) element to cleanse toluene and ehtyl benzene at IAQ levels. The S-doped TiO₂ was prepared by applying two popular processes and two well-known methods. For both target compounds, the two coating methods exhibited different photocatalytic oxidation (PCO) efficiency. Similarly, the two S-doping processes showed different PCO efficiency. These results indicate that the coating method and doping process are important parameters which can influence PCO efficiency. Meanwhile, it was found that the PCO efficiency of ethyl benzene was higher than that of toluene. In addition, the degradation efficiency of the target compounds increased as the relative humidity (RH) decreased. The PCO efficiency varied from 44% to 74% for toluene and from 68% to 95%, as the RH decreased. Consequently, it is suggested that with appropriate RH conditions, the visible-light-assisted photocatalytic systems can also become an important tool for improving IAQ.

양극산화법을 이용하여 광촉매 특성을 나타내는 TiO2 피막을 제조하고 염료의 분해반응을 통하여 광분해 효율을 조사하였다 양극산화법에 의해 제조된 산화피막은 모두 광촉매 분해특성이 있었으며 양극산화의 조건에 따라서 TiO2 피막의 성장거동과 피막 형태에 차이가 나타났다. 황산용액에서 양극산화된 TiO2 피막은 불규칙적 인 입자모양으로 anatase와 rutile이 혼합된 조직이었으며, 인산이 첨가된 혼합용액에서 형성된 TiO2는 anatase로 셀 모양의 피막형태로 생성되었다. 광촉매 특성에 적합한 양극산화의 인가 전압은 180V인 것으로 나타났다.

산화티탄의 광촉매 반응을 이용하여 휘발성 유기화합물(VOC)를 분해제거 하기 위하여 산화티탄을 glass bead에 sol-gel법으로 코팅하였다. 코팅막의 물성은 XRD, BET, SEM을 통해 분헉하였으며, 산화티탄이 galss bead를 채운 실험실규모의 광촉매 반응기를 이용 VOC중 벤젠 및 TCE 가스의 광촉매반응에 의한 분해효율에 대해 연구 컴토하였다. 반응기내의 잔류시간에 따른 가스농도 차이를 gas chromatography로 비교 분석하여 그 분해효율을 계산하였다. 이와 같은 정적인 상태의 실험결과, 400ppmv의 농도의 TCE인 경우 80%의 분해효율을 얻었으며, 50ppmv에서 300ppmv 농도의 벤젠인 경우 65%의 분해효율을 얻었다.

반도성 세라믹 광촉매 막 반응기(membrane reactor)에 의한 난분해성 유독 유기물질의 효율적인 분해공정을 개발하기 위한 기초 연구로서 TiO2 광촉매 막의 전기화학 반응에 의한 개미산(formic acid)의 산화/분해 효율성에 대해 연구하였다. 막 반응기는 용액의 여과(filtration)와 광전기화학 반응에 의한 유기물의 광분해를 동시에 수행할 수 있도록 제작되었다. 복합막의 담체임과 동시에 전극의 역할을 할 수 있는 전기 전도성 SnO2 또는 stainless steel 다공성 튜브상에 pH가 1.45인 TiO2 졸을 졸-겔 침지 코팅하여 광촉매 복합막을 제조하였으며 광원으로는 365 nm 파장을 갖는 UV를 사용하였다. TiO2 광촉매 막의 전기화학 반응에 의한 개미산의 산화효율은 전극에 걸어주는 전압과 반응시간에 따라 증가하였으나 투과량(flux)에는 거의 무관하였다. TiO2/SnO2 복합막을 사용한 경우 외부 전압을 27V 걸어주었을때 77% 정도의 산화효율을 얻을 수 있었으며 TiO2 /stainless steel 복합막에서는 90% 이상이었다. 광촉매 전기화학 반응을 이용함으로써 높은 투과량하에서도 개미산의 산화효율을 단순한 TiO2 광촉매 반응에서 보다 6~7배 가량 증진시킬 수 있었다.

The Electron/Hole Pair is generated when the activation energy produced by ultraviolet ray illuminates to the semiconductor and OH- ion produced by water photocleavage reacts with positive Hole. As a results, OH radical acting as strong oxidant is generated and then Photocatalytic oxidation reaction occurs. The photocatalytic oxidation can oxidate the non-degradable and hazardous organic substances such as pesticides and aromatic materials easier, safer and shorter than conventional water treatment process. So in this study, many factors influencing the oxidation of chlorophenols, such as inorganic electrolytes addition, change of oxygen and nitrogen atmosphere, temperature, pH, oxygen concentration, chlorophenol concentration, were throughly examined. According to the experiments observations, it is founded that the rate of chlorophenol oxidation follows a first-order reaction and the modified Langmuir-Hinshelwood relationship. And the photocatalytic oxidation occurs only when activation energy acting as Electron/Hole generation, oxygen acting as electron acceptor to prevent Electron/Hole recombination, $TiO_2$ powder acting as photocatalyst are present. The effects of variation of dissolved oxygen concentration, temperature and inorganic electrolytes concentration on 2-chlorophenol oxidation are negligible. And the lower the organic concentration, the higher the oxidation efficiency becomes. Therefore, the photocatalytic oxidation is much effective to oxidation of hazardous substances at very low concentration. The oxidation is effective in the range of 0.1 g/L-10 g/L of $TiO_2$. Finally when the ultra-violet ray is illuminated to $TiO_2$, the surface characteristics of $TiO_2$ change and Adsorption/Desorption reaction on $TiO_2$ surface occurs.

광촉매 TiO2 막에 의한 formic acid의 광분해 효율이 연구되었다. 막반응기는 용액의 정밀여과(micro-filtration)는 물론 유기물의 광분해를 동시에 수행할 수 있도록 다공성 TiO2 튜브 (평균기공: 0.2μm)를 이용한 새로운 타입으로 개발되었으며 광원으로는 365 nm 파장을 갖는 UV를 사용하였다. 또한 반응기의 광분해 효율을 증진시키기 위하여 슬립케스팅법으로 제조한 TiO2 튜브표면을 TiO2 졸로 코팅하였다. TiO2 막 반응기의 분해효율은 용액의 투과량(flux), 막의 미세구조(졸의 pH), 공급산소량, H2O2와 같은 1차 산화제(primary oxidants)의 첨가 그리고 Nb2O5와 같은 물질의 도핑(doping)에 매우 민감함을 알 수 있었다. 최적의 광분해 반응조건에서 formic acid의 산화효율은 pH가 1.45인 TiO2 졸로 코팅한 막 반응기를 사용했을때 80% 이상이었다. Formic acid 용액에 1차 산화제 H2O2를 첨가하거나 막을 Fe2O3로 도핑함으로써 산화효율은 최고 20%까지 증가시킬 수 있었다.

Background : For the green approach of nanoparticles synthesizing, plant based technology has been considered as cost-effective and eco-friendly mass production. The oriental medicinal crop, Kalopanax septemlobus (Thunb.) Koidz. (Korean name: 음나무), the deciduous tree and a family of Araliaceae. Endemic tree of Asian countries, K. septemlobus being used for the treatment of various diseases. Phytochemicals of K. septemlobus such as polyphenols has highly probability of reducing agent for biosynthesizing nanoparticles. Methods and Results : In this study, we applied K. septemlobus ZnO nanoparticles (Ks-ZnO NPs) with procedures including green approach one-pot synthesis. For the characterization of nanoparticles, UV–Vis, FTIR, XRD, SEM and TEM were used. The formation of ZnO nanoparticles, the aurface plasmon resonance were observed at 372 ㎚ in UV-Vis spectroscopy. The presence of functional groups which as a capping agent and formation of ZnO nanoparticles were confirmed in FTIR result. The crystallization and morphology showed by XRD, TEM and SEM respectively. The photocatalytic activity of ZnO nanoparticles, was determined using Methylene blue (MB) dye degradation under UV irradiation (365 ㎚) which resulted rate constant is (−k) 0.1215 with 97.5% of degradation in 30 min. Conclusion : The result shows that phytochemicals in K. septemlobus extract have a potential as a reducing agent to form ZnO nanoparticles. The ZnO NPs are capable to degrade MB with in brief time.

Background : Codonopsis lanceolata is a perennial herb called as ‘Deodeok’ (더덕) in Korea. The roots of C. lanceolate has been reported to have some antioxidant and antimicrobial properties. The chemically reactive saponins of C. lanceolata might be used as a capping agent for the surface of ZnO nanoparticle, ultimately making it a highly efficient photocatalyst. Methods and Results : In this paper, we report the one-pot green synthesis of ZnO nanoparticles via precipitation method using root extract of C. lanceolata. The structure of green synthesized Cl-ZnO NPs was characterized using XRD, EDX, DLS and morphology using TEM. The FT-IR exhibited the information about the functional groups that capped the metal nanoparticle and the formation of metal NPs was confirmed by UV–vis spectra at 356nm. The Cl-ZnO NPs were evaluated for their catalytic activity by measuring the degradation of methylene blue (MB) dye in aqueous solution under UV light (365 ㎚). The result showed efficient degradation of MB, which was degraded 70% within 30 min by Cl-ZnO NPs. Conclusion : This study proves that the green route synthesized ZnO NPs from the root extract of C. lanceolata are low cost, time efficient, bio-degradable and non- toxic. The UVvis spectra confirmed the synthesis of ZnO NPs from C. lanceolata root extract. The Cl- ZnO NPs mediated catalysis exhibited high photocatalysis rate in short time. Ultimately, the green rapid synthesized Cl-ZnO NPs from root extract can be used as an efficient

TiO2 광촉매 산화 공정의 효율은 수산기 라디칼의 생성량에 따라 크게 의존한다. 따라서 생성되는 수산기 라디칼의 정확한 정량이 공정을 평가하는데 필수적이다. 하지만 아직까지 이러한 수산기 라디칼 정량법이 마련되지 못했다. 이에 본 연구는 TiO2 광촉매 산화 반응에서 생성되는 수산기 라디칼을 정량화하기 위한 기존 분석법들을 비교하고, 기존 분석법들의 단점을 극복할 수 있는 새로운 방법을 제안하고자 수행되었다. TiO2 광촉매 산화 반응을 모사하기 위하여, 표준 TiO2 광촉매로서 널리 이용되고 있는 Degussa P25를 사용하였으며, 투여량은 0.05 g/L이었다. 그리고 UVC 수은 저압램프(11 W, 2,975 mW/cm2)를 광원으로 이용하였다. 연구결과, 기존에 많이 활용되고 있는 요오드화칼륨(KI)/UV-vis 분광분석법과 테레프탈산(TPA)/형광 분광분석법은 각각 요오드이온(I-)과 테레프탈산을 공정 중 생성된 수산기 라디칼과 반응시켜 발생하는 삼중요오드이온(I3-)과 2-하이드록시 테레프탈산을 검출하여 수산기 라디칼의 생성여부만을 확인할 수 있는 정성적인 분석법들이었다. 하지만 본 연구에서 테레프탈산 방법을 고성능 액체 크로마토그래프(HPLC) 분석법과 연계하였을 때 수산기 라디칼의 정량화가 가능하였다. 이렇게 새롭게 개발된 TPA/HPLC 분석법을 이용하여 측정한 결과, 본 연구의 실험 조건에서 8시간의 광촉매 산화 공정에 의해서 0.013 M의 수산기 라디칼이 생성되는 것을 확인하였다. 본 연구에서 제안하는 수산기 라디칼 정량법은 광촉매 산화 공정의 성능을 평가하는데 기여할 것으로 기대된다.

광석에서 순도 높은 금은을 추출하기 위해 사용된 청화법으로부터 시안이 유출되어 광석 내 존 재하는 중금속들과 결합하여 다양한 형태의 시안화합물이 생성된다. 이러한 시안화합물은 난분해성 오염물질로서 인간을 포함한 생태계에 악영향을 끼친다. 결합력에 따라서 중금속과 결합한 시안화합 물은 공유결합성 화합물(weak acid dissociable, WAD)과 착화합물(strong acid dissociable, SAD) 등으 로 분류할 수 있다. 본 연구에서는 시안화합물의 존재 형태별 광촉매 산화 효율을 비교 평가하였다. 특히 자외선 LED 광원의 파장과 광촉매 표면 개질이 시안화합물의 분해에 미치는 영향을 살펴보았 다. 실험 결과, 동일한 광촉매 산화 조건에서 자유 시안보다는 중금속과 결합한 시안화합물의 광산화 분해 효율이 떨어짐을 알 수 있었다. 그리고 자유 시안의 경우에는 짧은 파장에서 광촉매 산화가 효과 적이었지만 중금속과 결합한 시안화합물의 경우에는 긴 파장에서 광산화 분해능이 더 높게 나타났다. 그리고 광촉매 표면 개질에 의하여 광촉매 산화 공정의 성능을 향상시킬 수 있음을 확인하였다.