• 공업화학
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• 제32권5호
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• pp.516-523
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• 2021

본 연구는 대기 중 대표적인 미세먼지 2차 유발물질인 질소산화물 제어에 있어 암모니아를 환원제로 사용하는 선택적 촉매 환원법(Selective Catalytic Reduction; SCR)을 이용한 연구를 수행하였다. NH₃-SCR 실험은 상용촉매인 V/W/TiO₂와 Sb를 첨가한 V/W-Sb/TiO₂ 촉매를 사용하였으며 phosphorous에 의한 내피독성을 확인하였다. NH₃-SCR 실험 결과, Sb의 첨가는 P에 대한 내구성을 갖는 것으로 확인되었다. 또한 이에 대한 원인을 확인하기 위하여 BET, XPS, H₂-TPR, NH₃-TPD, FT-IR 분석을 통해 물리·화학적 특성을 비교분석하였다. 분석 결과 V/W/TiO₂ 촉매에 Sb 첨가 시 P가 첨가됨에 따라 SbPO₄ 결합을 형성하고 VOPO₄의 생성을 억제하였으며, P 첨가 전 촉매의 redox 특성을 유지함으로써 P에 대한 내피독성을 확인하였다.

• 대한화학회지
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• 제49권6호
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• pp.623-627
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• 2005

• 한국세라믹학회지
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• 제53권2호
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• pp.139-144
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• 2016

The dependence of the microwave dielectric properties of the glass-ceramic composite $0.9CaMgSi_2O_6-0.1MgSiO_3$ on the crystallization behaviour was investigated as functions of the $TiO_2$ content and heat-treatment temperature. The crystallization behaviour of the specimens was evaluated via a combination of the Rietveld and reference-intensity ratio methods. For specimens with a $TiO_2$ content of up to 1 wt.%, a monoclinic diopside phase was formed, whereas a secondary $TiO_2$ phase was formed with further increases in the $TiO_2$ content. The quality factor (Qf) of the specimens was strongly dependent on the degree of crystallization. The highest Qf value was obtained with a $TiO_2$ content of 0.5 wt.%, which was improved by increasing the heat-treatment temperature. The dielectric constant (K) was affected by the size of the crystallites and the $TiO_2$ content. The temperature coefficient of the resonant frequency (TCF) was nearly constant for all of the specimens, regardless of the $TiO_2$ content or heattreatment temperature.

• 대한토목학회논문집
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• 제26권3B호
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• pp.321-327
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• 2006

본 연구는 축산폐수처리를 위해 광촉매의 적용가능성과 처리효율 및 범위를 실험하여 축산폐수처리에 대한 기초 자료로 제시하고자 한다. 축산폐수처리에 대한 광촉매양의 증가는 높은 처리효율을 나타냈으며 알카리 영역에서 보다 산성영역 특히 pH3에서 축산폐수처리 효과는 우수하게 나타났다. 또한 광촉매양의 증가에 따라 색도 보다는 $TCOD_{Mn}$의 제거가 빠르게 이루어 졌다. UV 또는 $TiO_2$를 단독으로 사용하여 폐수처리를 하였을 때 보다 $UV/TiO_2$를 함께 적용하였을 때가 처리효율은 우수하게 나타났으며 산화제로 과산화수소를 주입하였을 때 처리효율은 $UV/TiO_2$만을 적용하였을 때 보다 처리효율이 우수하게 나타났다. 본 실험에서의 과산화수소 적정 주입량은 200 mg/L이며 과산화수소 적정주입량이 보다 많이 주입되었을 때는 처리효율이 떨어지는 것으로 나타났다. 또한 과산화수소의 주입량은 실험 시 계속적으로 주입이 되어야 높은 처리효율을 얻을 수 있었다.

• 유기물자원화
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• 제32권1호
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• pp.39-47
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• 2024

본 연구에서는 반도체 제조공정에서 발생한 실리콘 슬러지(SS)를 재활용하여 라이다 센서에 인식 가능한 검은색 소재(SS/bTiO₂)로 제조하고, 두 종류의 라이다 센서(MEMS 및 Rotating LiDAR)를 활용하여 제조한 소재의 인식률을 확인하였다. 상세히는, SS 표면의 금속 불순물을 제거하여 이산화티타늄을 도입하고 화학적 환원을 통해 SS/bTiO₂ 소재를 제조하였다. SS/bTiO₂는 투명 페인트와 혼합하여 친수성 검은색 도료로 제조하고 스프레이 건을 사용하여 유리 기판에 도포하였다. SS/bTiO₂ 기반의 도료는 상용화된 카본 블랙 기반의 도료와 유사한 명도(L^*=15.7)를 가짐과 동시에 우수한 근적외선 반사율(26.5R%, 905nm)을 나타내었다. 더불어, MEMS 및 Rotating 라이다를 통해서도 성공적으로 인식이 되는 것을 확인하였다. 이는 프레넬 반사 원리에 의해 검은색 이산화티타늄과 실리콘 슬러지 간의 계면에서 높은 반사가 일어났기 때문이다. 본 연구를 통해, 반도체 제조공정에서 발생하는 실리콘 슬러지를 효과적으로 재활용할 수 있는 새로운 응용 방안에 대하여 제시하였다.

• 한국물환경학회지
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• 제21권1호
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• pp.84-91
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• 2005

$TiO_2-catalyst$ suspensions work efficiently in Photocatalytic oxidation (PCO) for wastewater treatment. Nevertheless, once photocatalysis is completed, separation of the catalyst from solution becomes the main problem. The PCO of Cu(II)-EDTA was studied to determine the reusability of the titanium dioxide catalyst. Aqueous solutions of $10^{-4}M$ Cu(II)-EDTA were treated using illuminated $TiO_2$ particles at pH 6 in a circulating reactor. $TiO_2$ was reused in PCO system for treatment of Cu(II)-EDTA comparing two procedures: reuse of water and $TiO_2$ and reuse of the entire suspension after PCO of Cu(II)-EDTA. The results are as follows; (i) Photocatalytic efficiency worsens with successive runs when catalyst and water are reused without separation and filtration, whereas, when $TiO_2$ is separated from water, the reused $TiO_2$ is not deactivated. (ii) The $TiO_2$ mean recovery (%) with reused $TiO_2$ was 86.4%(1.73g/L). Although the mean initial degradation rate of Cu(II)-EDTA and Cu(II) was lower than that using fresh $TiO_2$, there was no significant change in the rate during the course of the three-trial experiment. It is suggested that Cu(II)-EDTA could be effectively treated using an recycling procedure of PCO and catalyst recovery. (iii) However, without $TiO_2$ separation, the loss of efficiency of the PCO in the use of water and $TiO_2$ due to Cu(II), DOC remained from previous degradation and Cu(II)-EDTA added to the same suspension was observed after 2 trials, and resulted in the inhibition of the Cu(II)-EDTA, Cu(II) and DOC destruction.

• 한국분말재료학회지
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• 제25권3호
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• pp.257-262
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• 2018

The coupling of two semiconducting materials is an efficient method to improve photocatalytic activity via the suppression of recombination of electron-hole pairs. In particular, the coupling between two different phases of $TiO_2$, i.e., anatase and rutile, is particularly attractive for photocatalytic activity improvement of rutile $TiO_2$ because these coupled $TiO_2$ powders can retain the benefits of $TiO_2$, one of the best photocatalysts. In this study, anatase $TiO_2$ nanoparticles are synthesized and coupled on the surface of rutile $TiO_2$ powders using a microemulsion method and heat treatment. Triton X-100, as a surfactant, is used to suppress the aggregation of anatase $TiO_2$ nanoparticles and disperse anatase $TiO_2$ nanoparticles uniformly on the surface of rutile $TiO_2$ powders. Rutile $TiO_2$ powders coupled with anatase $TiO_2$ nanoparticles are successfully prepared. Additionally, we compare the photocatalytic activity of these rutile-anatase coupled $TiO_2$ powders under ultraviolet (UV) light and demonstrate that the reason for the improvement of photocatalytic activity is microstructural.

• Bulletin of the Korean Chemical Society
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• 제25권7호
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• pp.1051-1054
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• 2004

The structural transformation behavior of $Na_2Ti_3O_7$ by hydrolysis was investigated in mild and strong acidic aqueous medium. Compared with $K_2Ti_4O_9,\;Na_2Ti_3O_7$ exhibits quite different structural and morphological transformation behavior despite their similar layered structural characteristics. $TiO_2(B)$ obtained by heat treatment of $H_2Ti_3O_7\;at\;350^{\circ}C$ transforms to rutile $H_2Ti_3O_7\;at\;900^{\circ}C$. This temperature is much lower than $1200{\circ}C$, the temperature for anatase to rutile transition when $K_2Ti_4O_9$ is used as a starting titanate. A rectangular rod shape and size of $TiO_2(B)$ particles obtained from $Na_2Ti_3O_7$ is also different from a fibrous structure of $TiO_2(B)$ prepared using $K_2Ti_4O_9$. Rutile crystals of 100 nm diameter with a corn-like morphology and large surface area are directly obtained when the hydrolysis of $Na_2Ti_3O_7$ is carried out at $100^{\circ}C$ in a strong acid solution. The structure of starting titanates and the hydrolysis conditions are an important factor to decide the particle size and morphology of $TiO_2(B)\;and\;TiO_2$.

• 한국전기전자재료학회논문지
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• 제33권5호
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• pp.373-379
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• 2020

In this study, TiN-coated cBN (cubic-structure boron nitride) powders were successfully synthesized by a sol-gel method using titanium (IV) isopropoxide (TTIP) and by controlling the heat treatment conditions. After the sol-gel process, amorphous nano-sized TiO_x was uniformly coated on the surface of cBN powder particles. The obtained TiO_x-coated cBN powders were heated at 1,000~1,300℃ for 1 or 6 h in a flow of 95%N₂-5%H₂ mixed gas. With increasing temperature, the chemical composition of the TiO_x coating layer changed in the order of TiO₂→Ti₆O₁₁→Ti₄O₇→TiN due to reduction of the Ti ions. The TiN coating layer was observable in the samples heated at 1,200℃ and appeared as the main phase in the sample heated at 1,300℃. The resulting thickness of the TiN coating layer of the sample heated at 1,300℃ was approximately 45~50 nm.

• 한국전기전자재료학회논문지
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• 제29권12호
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• pp.791-795
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• 2016

The effects of $TiO_2$ addition on the electrical insulation of AlN ceramics with 1 wt% $Y_2O_3$ as a sintering aid have been investigated. Some of $TiO_2$ has reacted with AlN powders and transformed to fine TiN particles during sintering, which was uniformly dispersed along grain boundaries of AlN. At a high electrical field (500 V/mm), the resistivity of AlN ceramics with $TiO_2$ addition of 0.2 wt% increased about 1000 times from $3{\times}10^{10}{\Omega}cm$ to $3.1{\times}10^{13}{\Omega}cm$. Based on the impedance spectroscopy measurement, it was found that $TiO_2$ addition increased dramatically electrical resistivity of AlN grains much more than that of grain boundaries. Thus, $TiO_2$ was believed to dissolve inside AlN grains to suppress ionic conduction of Al vacancies. This suppressed ionic conduction by Ti incorporation into AlN grains seems to contribute to more electrically insulating AlN ceramics.