• 공업화학
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• 제7권6호
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• pp.1034-1042
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• 1996

DCCA로 1-도데카놀을 이용한 수식 졸-겔법에 의한 $TiO_2-SiO_2$계분체를 합성하였으며, 이들 합성분체에 대한 characterization과 광활성촉매에 대해 검토하였다. $500^{\circ}C$까지의 감량변화는 TiO2단독분체가 33.0wt%, $TiO_2/SiO_2$의 몰비가 75/25, 50/50 및 25/75인 분체는 각각 67.0wt%, 70.0wt% 및 73.0wt%, 그리고 $SiO_2$단독분체는 42.5wt%이였다. 이들 탈리는 거의 대부분이 유기물질이였다. 합성직후의 분체는 $TiO_2$단독분체를 제외하고는 무정형화합물이였고, 아나타아제의 루틸로의 상전이는 $SiO_2$에 의해 억제되었다. 합성직후의 분체는 입자의 형태가 관찰되지 않았으나, $600^{\circ}C$, 1시간 가열에 의한 $TiO_2$단독분체, $TiO_2/SiO_2$의 몰비가 75/25 및 50/50인 분체는 모두 서브미크론의 입자를 보였으며, 몰비가 25/75의 분체 및 $SiO_2$단독분체는 여전히 벌크상태였다. 비표면적 역시 $SiO_2$의 증가와 함께 증가하였으며, 세공크기 역시 $SiO_2$성분에 의존하였다. 그리고 이들 가열물의 광촉매활성은, $TiO_2/SiO_2$의 몰비가 75/25인 분체의 경우, 수소발생량으로 $0.240{\mu}mol/h.g-cat.$을 나타내었으며, $TiO_2$단독분체의 그것보다는 약 2.6배, 표준광촉매물질인 P-25(Degussa P-25)보다는 약 2.0배 가량 큰 값을 나타냈다.

• 한국환경과학회지
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• 제15권6호
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• pp.533-538
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• 2006

Removal of $NO_x$ on $CaO/TiO_2$ photocatalyst manufactured by the addition of $Ca(OH)_2$ was measured in relation with the amount of $Ca(OH)_2$ and calcination temperature. In case of pure $TiO_2$, the $NO_x$ removal decreased greatly with the increase of calcination temperature from $500^{\circ}C\;to\;700^{\circ}C$, whereas in the photocatalyst added with $Ca(OH)_2$, the removed amount of $NO_x$ was high and constant regardless of calcination temperature. Considering $NO_x$ removal patterns depending on the amount of $Ca(OH)_2$ added(50, 30, 10wt%), high removal rate showed at the photocatalysts containing less than 30wt% of $Ca(OH)_2$, and it was about 30% higher than that of pure $TiO_2$. From the XRD patterns, it is seen that the addition of $Ca(OH)_2$ contributes to maintaining the anatase structure that is favourable to photocatalysis. It also indicates that the possibility of the formation of calcium titanate($CaTiO_3$) by reacting with $TiO_2$ above $700^{\circ}C$. Apart from the favourable crystalline structure, the addition of $Ca(OH)_2$ helped increase the alkalinity of photocatalyst surface, thus promoting the photooxidation reaction of $NO_x$.

• 한국건설순환자원학회논문집
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• 제6권2호
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• pp.108-114
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• 2018

콘크리트 구조물은 사용기간 동안 표면 열화 및 오염으로 인해 미관의 저하 및 내구성 저하가 발생된다. 최근 들어 광촉매(photocatalyst)를 이용하여 유기산화물을 제거하고 표면자기정화(self cleaning) 성능을 개선하려는 연구가 시도되고 있다. 본 논문은 실리케이트 기반 광촉매 함침을 위한 기초연구로서 CS와 SC 두 가지 함침 용액을 대상으로 하였다. 실리케이트 기반 용액의 점성과 표면장력을 평가하였으며 콘크리트에 적용하여 부착강도를 평가하였다. 또한 실리케이트 용액에 침지된 콘크리트에 대하여, 광촉매 용액의 침지 및 분무를 한 후 콘크리트 강도 평가와 SEM을 통한 표면상태를 조사하였다. 실리케이트 용액의 침지 후 30분간 기건 상태를 유지하고 분무하는 방법이 가장 효과적으로 광촉매의 표면 흡착을 유도하는 것으로 평가되었으며, 강도 개선에도 효과적임을 알 수 있다.

• 한국가스학회지
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• 제10권2호
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• pp.1-6
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• 2006

본 연구에서는 실내 오염물질인 포름알데히드가스를 제거하기위하여 $Pd/TiO_2$로 코팅한 극세 섬유에 광분해 효과를 제안하였다 광촉매 반응기는 사각박스(부피 2 l)내에 UV램프와 $Pd/TiO_2$로 코팅한 극세 섬유와 함께 장착하였다. 이 때 Langmuir-Heinshelwood의 반응속도와 흡착상수, 온도 및 농도 변화에 따른 전환을 그리고 습도변화와 오염가스($SO_2$) 혼합으로 인한 전환율의 영향을 조사하였다. 결과로서 속도상수(k)와 흡착상수($\beta$) 각각 114.94 ppmv/min, $0.0036ppmv^{-1}$을 얻었다. 또한 온도증가($40^{\circ}C{\sim}80^{\circ}C$)에 따른 포름알데히드가스 전환율이 약 20%로 감소하고 습도변화에 따른 전환율에서는 습도가 증가할수록 감소하는 경향을 보였다. 이외에 $SO_2$가스 혼입되어 있는 상태에서 전환율은 $SO_2$ 가스가 수분에 의한 이온의 영향으로 방해인자로 작용하는 것을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제35권3호
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• pp.913-918
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• 2014

Five mol % tungsten-doped tin oxide ($W_{0.05}Sn_{0.95}O_2$, TTO5) was prepared by co-precipitation of $SnCl_4{\cdot}5H_2O$ and $WCl_4$, followed by calcination at $1000^{\circ}C$. The as-prepared TTO5 was in the pure cassiterite phase with a particle size of ~50 nm and optical bandgap of 2.51 eV. Herein it was applied for the formation of TTO5/$TiO_2$ heterojunctions by covering the TTO5 surface with $TiO_2$ by sol-gel method. Under visible-light irradiation (${\lambda}{\geq}420$ nm), TTO5/$TiO_2$ showed a significantly high photocatalytic activity in removing gaseous 2-propanol (IP) and evolving $CO_2$. It is deduced that its high visible-light activity is caused by inter-semiconductor holetransfer between the valence band (VB) of TTO5 and $TiO_2$, since the TTO5 nanoparticle (NP) exhibits the absorption edge at ~450 nm and its VB level is located more positive side than that of $TiO_2$. The evidence for the hole-transport mechanism between TTO5 and $TiO_2$ was also investigated by monitoring the holescavenging reaction with 1,4-terephthalic acid (TA).

• 한국환경보건학회지
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• 제35권2호
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• pp.124-129
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• 2009

The photocatalysis degradation of simazine, s-triazine type herbicide was carried out using circulating photo reactor systems. In order to search for the effective method to mineralize this compound into environmentally compatible products, this study compared the removal efficiencies of simazine by changing various parameters. First, under the photocatalytic condition, simazine was more effectively degraded than by photolysis and $TiO_2$ only condition. With photocatalysis, 5 mg/l simazine was degraded to approximately 90% within 30 min, and completely degraded after 150 min. Ionic byproducts such as ${NO_2}^-$, ${NO_3}^-$, and $Cl^-$ were detected from the photocatalysis of simazine, however, the recoveries were poor, indicating the presence of organic intermediates rather than the mineralization of simazine during photocatalysis. Two bioassays using V. fischeri and D. magna were employed to measure the toxicity reduction in the reaction solutions treated by both photocatalysis and photolysis. Simazine and its photocatalysis treated water did not exert any significant toxicity to V. fischeri, marine bacterium. However, the acute toxicity test using D. magna indicates that initial acute toxicity ($EC_{50}$ = 57.30%) was completely reduced ($EC_{50}$ = 100%) after 150 min under both photocatalysis and photoysis of simazine. This results indicates that photocatalysis and photolysis of simazine reduced the acute toxicity through mineralization.

• 한국환경과학회지
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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.

• Bulletin of the Korean Chemical Society
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• 제35권12호
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• pp.3521-3526
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• 2014

A magnetic sonophotocatalyst $Fe_3O_4@SiO_2@TiO_2$ is synthesized for the enhanced biodegradability of organophosphate pesticide. The as-prepared catalysts were characterized using different techniques, such as X-ray diffraction (XRD) and transmission electron microscopy (TEM). The radial sonophotocatalytic activity of $Fe_3O_4@SiO_2@TiO_2$ nanocomposite was investigated, in which commercial dichlorvos (DDVP) was chosen as an object. The degradation efficiency was evaluated in terms of chemical oxygen demand (COD) and enhancement of biodegradability. The effect of different factors, such as reaction time, pH, the added amount of catalyst on $COD_{Cr}$ removal efficiency were investigated. The average $COD_{Cr}$ removal efficiency reached 63.13% after 240 min in 12 L sonophotocatalytic reactor (catalyst $0.2gL^{-1}$, pH 7.3). The synergistic effect occurs in the combined sonolysis and photocatalysis which is proved by the significant improvement in $COD_{Cr}$ removal efficiency compared with that of solo photocatalysis. Under this experimental condition, the $BOD_5/COD_{Cr}$ ratio rose from 0.131 to 0.411, showing a remarkable improvement in biodegradability. These results showed that sonophotocatalysis may be applied as pre-treatment of pesticide wastewater, and then for biological treatment. The synthesized magnetic nanocomposite had good photocatalytic performance and stability, as when it was used for the fifth time, the $COD_{Cr}$ removal efficiency was still about 62.38%.

• Bulletin of the Korean Chemical Society
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• 제35권8호
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• pp.2295-2298
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• 2014

To effectively destruct 2-chlorophenol, a representative sterile preservative, nanometer-sized Mn (0.5, 1.0, 3.0 mol %)-incorporated $TiO_2$ powders were synthesized by a solvothermal method. XRD result demonstrated that the Mn ingredients were perfectly inserted into $TiO_2$ framework. The Mn-$TiO_2$ particles exhibited an anatase structure with a particle size of below 20 nm. The absorbance was shifted to the higher wavelength on Mn-$TiO_2$ compared to that of $TiO_2$. Otherwise, the PL intensities which has a close relationship for recombination between holes and electrons significantly decreased on Mn-$TiO_2$. The photodecomposition for 2-chlorophenol in a liquid system was enhanced over Mn-doped $TiO_2$ compared with pure $TiO_2$: 2-chlorophenol of 50 ppm was completely decomposed after 12 h when 1.0 mol % Mn-$TiO_2$ was used. Consequently, the core of this paper is as follows. introducing Mn into $TiO_2$ framework reduced the band-gap, moreover, it played as an electron capture resulted to lower recombination between electrons and holes during photocatalytic reaction for removal of 2-cholophenol.

• 대한토목학회논문집
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• 제35권3호
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• pp.691-698
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• 2015

대도시와 인접한 고속도로와 같이 교통량이 많은 경우 스모그와 산성비의 주요 원인이 되는 많은 양의 질소산화물이 발생하여 대기오염이 심각한 상황이다. 이에 최근 들어 전 세계적으로 질소산화물 제거의 중요성이 부각되고 있다. $TiO_2$는 광촉매 소재의 하나로써 질소산화물 제거에 매우 효과적이므로 대기오염의 주요 원인인 질소산화물을 제거하기 위하여 $TiO_2$ 콘크리트를 도로 구조물에 적용하는 방안이 있다. 이에 본 실험적 연구에서는 $TiO_2$ 콘크리트의 현장 적용을 위하여 공용에 따른 질소산화물 제거 효율변화와 함께 환경 하중 저항성을 평가하였다. 이로 인해 $TiO_2$ 콘크리트의 장기적인 기능성 유지가 확인되었으며, 인접 도로 구조물에 적용이 타당할 것으로 판단된다.