• 공업화학
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• 제31권4호
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• pp.390-397
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• 2020

To synthesize non-corrosive metallic gold colored α-Al₂O₃ nanoplate-TiO₂ core-shell pigments with controlled roughness, we systematically checked the morphological variation of the TiO₂ shell with the mole ratio of TiCl₄ and NaOH from 1 : 1 to 1 : 1.5, 1 : 2, 1 : 2.5, 1 : 3, 1 : 3.5, and 1 : 4. The more increased mole ratio of TiCl₄ and NaOH resulted in the smoother TiO₂ shell due to the promoted formation of anatase TiO₂ than that of the rutile one. By the heat-treatment of pigments at 500 ℃, we could improve the adhesiveness between TiO₂ shell and α-Al₂O₃ nanoplates without changing their topology and roughness. In addition, the α-Al₂O₃ nanoplate with the robust TiO₂ by heat-treatment exhibited comparable photo-stability against photo-catalytic degradation by UV exposure compared with the commercially available α-Al₂O₃/TiO₂ lustering pigment.

• 대한환경공학회지
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• 제27권1호
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• pp.59-66
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• 2005

[ $TiO_2$ ]박막은 DC 마그네트론 스퍼터링법을 이용하여 다양한 스퍼터링 파라미터(전력 $0.6{\sim}5.2\;kw$, 기판온도 실온${\sim}350^{\circ}C$, 산소량 $0{\sim}50\;sccm$($O_2+Ar$ 90 sccm, 압력은 약 1 mtorr))를 통하여 증착되었다. TiO-N박막도 가스의 유량비를 제외하고는 $TiO_2$박막과 같은 스퍼터링 조건하에서 증착되었다. 이러한 스퍼터링 파라미터에서 증착된 박막의 전기적 특성을 분석하기 위하여 시트저항을 측정하였고, 박막의 두께(${\alpha}$-step), 표면 거칠기(AFM), 형성 조직(FE-SEM, XRD)을 분석하여 최적 스퍼터링 파라미터를 도출하였다. 최적 스퍼터링 파라미터에서 제조된($TiO_2$, TiO-N)박막을 이용하여 광활성도를 평가하기 위하여 VOCs물질 중 toluene, 반응성 염료인 Suncion Yellow를 대상 물질로 선정하여 적용성 연구를 수행하였다. 실험에서 광촉매 박막은 적용물질에 대해서 광활성을 양호하게 보였으며, 특히 TiO-N광촉매 박막은 가시광 영역에서도 최대 33%의 톨루엔(5 ppm) 제거 효율을 나타내었다.

• 한국안광학회지
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• 제10권3호
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• pp.185-191
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• 2005

Ti-naphthenate를 출발물질로 사용하여 스핀코팅으로 soda-lime-silica 유리에 $TiO_2$ 박막을 제조하였다. $500^{\circ}C$에서 $600^{\circ}C$의 열처리온도에 따라 제조된 악악의 광학적, 구조적 및 광촉매 특성을 측정하였다. 재조된 $TiO_2$박막의 투과율은 가시광선 영역에서 약 80%정도의 평균투과율을 보였고, 열처리 온도가 높아짐에 따라 흡수밴드가 낮은 UV 파장영역으로 편향하였으며, 전체 광투과율은 소폭 감소하는 경향을 나타냈다. $TiO_2$ 박막의 열처리 온도가 높아짐에 따라 굴절률은 2.16에서 2.63으로 증가하였고, 박막의 두께는 484nm에서 439nm으로 감소하였다. $500^{\circ}C$에서 $600^{\circ}C$의 모든 열처리 온도에서 anatase 결정상을 보였으며, 표면조도는 $500^{\circ}C$와 $550^{\circ}C$에서 열처리한 박막에 비하여 $600^{\circ}C$에서 크게 증가하였다. 또한 제조된 $TiO_2$ 박막의 광촉매 특성에 있어서 초기 접촉각은 $600^{\circ}C$의 경우 가장 낮은 값을 보였으며, $550^{\circ}C$와 $500^{\circ}C$로 열처리한 경우 UV광자극에 의해 45분 이내에 친수성박막으로 변이하였고 UVC-UVA-UVB 순으로, $600^{\circ}C$ 의 경우에는 UVA-UVC-UVB의 순으로 높은 광활성을 보였다.

• Bulletin of the Korean Chemical Society
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• 제30권5호
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• pp.1047-1053
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• 2009

The future use of hydrogen as an energy source is expected to increase on account of its environmentally friendliness. In order to enhance the production of hydrogen, Pd ions (0.01, 0.05, 0.1, and 0.5 mol%) were incorporated $TiO_2$ (Pd-$TiO_2$) and used as a photocatalyst. The UV-visible absorbance decreased with increasing level of palladium incorporation without a wavelength shift. Although all the absorption plots showed excitation characteristics, there was an asymmetric tail observed towards a higher wavelength caused by scattering. However, the intensity of the photoluminescence (PL) curves of Pd-$TiO_2$ was smaller, with the smallest case being observed at 0.1 and 0.5 mol% Pd-$TiO_2$, which was attributedto recombination between the excited electrons and holes. Based on these optical characteristics, the evolution of $H_2$ from methanol/water (1:1) photo-splitting over Pd-$TiO_2$ in the liquid system was enhanced, compared with that over pure $TiO_2$. In particular, 2.4 mL of $H_2$ gas was produced after 8 h when 0.5 g of a 1.0 mol% Pd-$TiO_2$ catalyst was used. $H_2$ was stably evolved even after 28 h without catalytic deactivation, and the amount of $H_2$ produced reached 14.5 mL after 28 h. This is in contrast to the case of the Pd 0.1 mol% impregnated $TiO_2$ of $H_2$ evolution of 17.5 mL due to the more decreasedelectron-hole recombination.

• 태양에너지
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• 제8권1호
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• pp.49-56
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• 1988

Thermally treated Korean ilmenite was characterized and used for water splitting to obtain hydrogen by photo-catalytic reaction. Experiments on specific surface area, X-ray diffraction and EDS showed that the formation of FeO, $Fe_2O_3$ and $TiO_2$ ilmenite crystal surface increased the specific surface area with maximum value, phase change of $TiO_2$ at $600^{\circ}C$ and hetrogeneity. The hydrogen evolved in caustic soda solution on these ilmenites indicated that there was a maximum yield point at about $600^{\circ}C$. This point was explained with the change of the surface area due to sintering of newly formed FeO, $Fe_2O_3$ and $TiO_2$, as well as crystal phase change of anatase to rutile at $600^{\circ}C$. Produced hydrogen increased also as the concentration of caustic soda, but become constant at the near 1N solution.

• 한국산학기술학회논문지
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• 제14권2호
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• pp.846-849
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• 2013

$TiO_2$ 박막을 저온 열처리 졸-겔 법으로 합성하였다. 박막의 기판은 면적이 $100mm^2$인 붕규산염 유리를 사용하여 시료를 $300^{\circ}C$부터 $1100^{\circ}C$까지 열처리하였고, 이때 제조된 박막의 두께는 약 $1.5{\mu}m$정도였다. $300^{\circ}C$에서 2시간 동안 열처리한 $TiO_2$ 박막은 아나타제 상을 나타내었고 열처리 온도가 증가함에 따라 비정질 상태에서 아나타제상과 루타일 상이 공존하면서 각 상의 분율이 변화하였다. SEM 분석에 의하면 박막의 입자 크기는 $0.1{\sim}0.54{\mu}m$이었으며 Uv-visible 반사특성에 있어서 390nm부근에서 광흡수가 되는 것을 알 수 있었다. 따라서 낮은 열처리 온도에서 생성된 $TiO_2$ 박막은 주로 아나타제 상을 가지며 광촉매 특성을 2.4배 증가시키는 것으로 나타났다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
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• pp.387-392
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• 2005

For the production of further functional bio-degradable plastic(polybutylene succinate:PBS) with $TiO_{2}$ as photocatalyst, which shows the decomposition of detrimental organic compound and pollutant under ultraviolet irradiation, we attempted to prepare $TiO_{2}$ coatings on PBS substrate by HVOF and plasma spraying techniques under various conditions. The microstructures of coatings were characterized with SEM and XRD analysis, and the photocatalytic efficiency of coatings was evaluated through the photo degradation of gaseous acetaldehyde. The effects of primary particle size and spraying parameters on the formation behavior, photo catalytic performance and mechanical characteristics of the coatings have been investigated. The results indicated that with respect to both the HVOF sprayed $P_{200}$ and $P_{30}$ coatings, the high anatase ratio off 100% can be achieved regardless of fuel gas pressure. On the other hand, the HVOF sprayed $P_{7}$ coating exhibited largely decreased anatase ratio (from 100% to 49.1%) with increasing the fuel gas pressure, which may be attributed to the much higher susceptibility to heat of 7nm agglomerated powder. In terms of photocatalytic efficiency, HVOF sprayed $P_{200}$ and $P_{30}$ coatings seem to predominate as compared to that of plasma sprayed $P_{200}$ coatings owing to the higher anatase ratio. However, the HVOF sprayed $P_{7}$ coatings didn't show the photo catalytic activity, which may result from the extremely small reaction surface area to the photo-catalytic activity and low anatase ratio. Such functional PBS with new roles is expected to cosiderably contribute to the reduction of aggravated environmel problem.

• 한국환경과학회지
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• 제21권4호
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• pp.411-419
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• 2012

In this study, Ibuprofen (IBP) degradation by the photo catalytic process was investigated under various parameters, such as UV intensity, optimum dosage of $TiO_2$, alkalinity, temperature and pH of bulk solution. The pseudo-first order degradation rate constants were in the order of $10^{-1}$ to $10^{-4}min^{-1}$ depending on each condition. The Photocatalytic IBP degradation rate increased with an increase in the applied UV power. At high UV intensity a high rate of tri-iodide ($I_3{^-}$) ion formation was also observed. Moreover, in order to avoid the use of an excess catalyst, the optimum dosage of catalyst under the various UV intensities (30 and 40 W/L) was examined and ranged from approximately 0.1 $gL^{-1}$. The photo catalytic IBP degradation rate was changed depending on the alkalinity and temperature and pH in the aqueous solution. This study demonstrated the potential of photo catalytic IBP degradation under different conditions.

• 한국광물학회지
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• 제28권1호
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• pp.29-38
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• 2015

광석에서 순도 높은 금은을 추출하기 위해 사용된 청화법으로부터 시안이 유출되어 광석 내 존재하는 중금속들과 결합하여 다양한 형태의 시안화합물이 생성된다. 이러한 시안화합물은 난분해성 오염물질로서 인간을 포함한 생태계에 악영향을 끼친다. 결합력에 따라서 중금속과 결합한 시안화합물은 공유결합성 화합물(weak acid dissociable, WAD)과 착화합물(strong acid dissociable, SAD) 등으로 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 살펴보았다. 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 효과적이었지만 중금속과 결합한 시안화합물의 경우에는 긴 파장에서 광산화 분해능이 더 높게 나타났다. 그리고 광촉매 표면 개질에 의하여 광촉매 산화 공정의 성능을 향상시킬 수 있음을 확인하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1255-1260
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• 2004

Decomposition of ozone at room temperature was investigated comparatively with commercial monolithic ozone decomposition catalyst (ODC, $MnO_2$) and monolithic photo catalyst ($TiO_2$). The effects of residence time, UV (ultraviolet) light dependence and ozone concentration on the conversion was presented. UV ray was irradiated using BLB (black light blue) lamp ($315{\sim}400$ nm), supplied with a constant intensity in the reactor. The concentration of ozone in the square-shape reactor can be controlled by combining the DBD (dielectric barrier discharge) reactor with an AC high voltage supply system. The catalytic performance, in presence of UV irradiation did not show significant changes for $MnO_2$ catalyst. $TiO_2$ catalyst was the different case, which showed higher decomposition activity in presence of UV irradiation. Deactivation of catalyst detected by real-time ozone monitor for 120 hours with a constant inlet ozone concentration.