• 한국막학회:학술대회논문집
• /
• 한국막학회 2004년도 Proceedings of the second conference of aseanian membrane society
• /
• pp.39-42
• /
• 2004

Ceramic membranes have attracted a great attention because they have excellent resistance to most organic solvents and can be used over a wide temperature range. Especially, titania (titanium oxide, TiO$_2$) shows excellent chemical resistance and can be used both acidic and alkali solutions, and therefore, titania is one of the most promising materials for the preparation of porous membranes; titania membranes having pore sizes in the range of nanofiltration (NF) to ultrafiltration (UF) membrane have been prepared by the sol-gel process (Tsuru 2001).(omitted)

• 한국결정성장학회지
• /
• 제25권6호
• /
• pp.280-284
• /
• 2015

Au doped $TiO_2$ nanoparticles have been synthesized using a reverse micelle technique combined with metal alkoxide hydrolysis and condensation. Au doped $TiO_2$ was coated with glass substrate. The size of the particles and thickness of the coating can be controlled by manipulating the relative rates of the hydrolysis and condensation reaction of TTIP within the micro-emulsion. The average size of synthesized Au doped $TiO_2$ nanoparticle was about in the size range of 15 to 25 nm and the Au particles formed mainly the range of 2 to 10 nm in diameter. The effect of synthesis parameters, such as the molar ratio of water to TTIP and the molar ratio of water to surfactant, are discussed. The synthesized nanopaticles were coated on glass substrate by a spin coating process. The thickness of thin film was about 80 nm. The degradation of MB on a $TiO_2$ thin film was enhanced over 20 % efficiency by the incorporation of Au.

• Advances in environmental research
• /
• 제1권4호
• /
• pp.289-304
• /
• 2012

Tris (2-methyl-1-aziridinyl) phosphine oxide (MAPO) is extremely poisonous and persistent in aqueous media. An efficient UV/nano$TiO_2$ process was employed for its mineralization in a high duty falling film photo-reactor based on an experimental design scheme that considers interactions between the main variables. The influencing variables and their range were determined with preliminary studies. The results show substrate mineralization to some extent under mild conditions of: T = $30^{\circ}C$, pH = 8.5, $[MAPO]_0=60\;mg\;L^{-1}$ and $[TiO_2]=110\;mg\;L^{-1}$. The relative importance of the influencing parameters were initial pH > temperature > $[MAPO]_0$ > [$TiO_2$]; while the interdependence of all the parameters was significant. Accordingly, a reduced quadratic expression was developed. Meanwhile, mineralization kinetic studies, based on chemical oxygen demand, revealed a power law model with order of 2.6 during process time until 150 min.

• Advances in environmental research
• /
• 제3권1호
• /
• pp.29-43
• /
• 2014

Pharmaceutical wastewater effluents are well known for their difficult elimination by traditional biotreatment methods and their important contribution to environmental pollution due to its fluctuating and recalcitrant nature. OTC is one of the nonbiodegradable antibiotics that makes antibiotic-resistant, so it can make be high risk for environment. NZVI can be a good choice for removal of OTC in aqueous solution. Response surface methodology (RSM) was used to optimize the amounts of NZVI and OTC to be used at pH 3 and under 200 W, UV-A irradiation. The responses were removal percent of absorption at 290 and 348 nm, TOC and COD of OTC. In the optimum condition, Linear model was performed 155 ppm of OTC were removed by 1000 ppm NZVI after 6.5 hours and the removal efficiency of absorption at 290 and 348 nm, TOC and COD were 87, 95, 85 and 89 percent, respectively. In the similar process, there is no organic compound after 14 hours. The parameters ORP, DO and pH were investigated for 6:30 hours to study the type of NZVI reaction in process. In the beginning of reaction, oxidation was the dominant reaction after 3 hours, photocatalytic reaction was remarkable. The mechanism of OTC degradation is proposed by HPLC/ESI-MS and four by products were found. Also the rate constants (first order kinetic chain reaction model) were 0.0099, 0.0021, 0.0010, 0.0049 and $0.0074min^{-1}$, respectively.

• 산업기술연구
• /
• 제22권B호
• /
• pp.117-124
• /
• 2002

We prepared the nano-sized $TiO_2$ particles by the diffusion flame reactor and investigated the effects of several process variables on the generation and transport properties of $TiO_2$ particle. As the length from the tip of diffusion flame reactor increases, the size of $TiO_2$ particle increases by the coagulation between particles. The structure of $TiO_2$ particles prepared is almost found to be anatase. It was found that the $TiO_2$ particle size depends more largely on the change of reactor temperature than on the change of inlet $TiCl_4$ concentration. By the photo-degradation experiment of phenol and toluene with the prepared $TiO_2$ particles, we found that the photo-degradation efficiencies of phenol and toluene change, depending on the process variables such as size of $TiO_2$ photocatlysts, concentration of phenol or toluene. Degradation efficiencies of phenol and toluene was above 90% in our experiments in 60 minutes.

• 한국분말재료학회지
• /
• 제24권4호
• /
• pp.326-331
• /
• 2017

The structural formation of inorganic nanoparticles dispersed in polymer matrices is a key technology for producing advanced nanocomposites with a unique combination of optical, electrical, and mechanical properties. Barium titanate ($BaTiO_3$) nanoparticles are attractive for increasing the refractive index and dielectric constant of polymer nanocomposites. Current synthesis processes for $BaTiO_3$ nanoparticles require expensive precursors or organic solvents, complicated steps, and long reaction times. In this study, we demonstrate a simple and continuous approach for synthesizing $BaTiO_3$ nanoparticles based on a salt-assisted ultrasonic spray pyrolysis method. This process allows the synthesis of $BaTiO_3$ nanoparticles with diameters of 20-50 nm and a highly crystalline tetragonal structure. The optical properties and photocatalytic activities of the nanoparticles show that they are suitable for use as fillers in various nanocomposites.

• 한국응용과학기술학회지
• /
• 제25권2호
• /
• pp.130-136
• /
• 2008

$xTiO_2$-$ySiO_2$ 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 $xTiO_2$-$ySiO_2$ 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 $SiO_2$ 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 $60TiO_2$-$40SiO_2$ catalyst.

• Korean Chemical Engineering Research
• /
• 제57권2호
• /
• pp.259-266
• /
• 2019

Tuning of electro-optical properties of nano-structured $SnO_2:Ga$ powders in a micro drop fluidized reactor (MDFR) was highly effective to enhance the activities of powders to be used as sensor materials. The tuning was conducted continuously in a facile one-step process during the formation of powders. The microscopic hydrodynamic forces affected the band gap structure and charge transfer of $SnO_2:Ga$ powders through the oxygen and interfacial tin vacancies by providing plausible pyro-hydraulic conditions, which resulted in the decrease in the electrical resistance of the materials. The analyses of room-temperature photoluminescence (PL) spectra and FT-IR exhibited that the tuning could improve the surface activities of $SnO_2:Ga$ powders by adjusting the excitation as well as separation of electrons and holes, thus maximizing the oxygen vacancies at the surface of the powders. The scheme of photocatalytic mechanism of $SnO_2:Ga$ powders was also discussed.

• 한국환경과학회지
• /
• 제17권9호
• /
• pp.1023-1032
• /
• 2008

The feasibility study of the application of the photoelectrocatalytic and electrolytic/UV decolorization of Rhodamine B (RhB) was investigated in the photoelectrocatalytic and electrolytic/UV process with $TiO_2$ photoelectrode and DSA (dimensionally stable anode) electrode. Three types of $TiO_2$ photoelectrode were used. Thermal oxidation electrode (Th-$TiO_2$) was made by oxidation of titanium metal sheet; sol-gel electrode (5G-$TiO_2$) and powder electrode (P-$TiO_2$) were made by coating and then heating a layer of titania sol-gel and slurry $TiO_2$ on titanium sheet. DSA electrodes were Ti and Ru/Ti electrode. The relative performance for RhB decolorization of each of the photoelecoodes and DSA electrodes is: Ru/Ti > Ti > SG-$TiO_2$ > Th-$TiO_2$. It was observed that photoelectrocatalytic decolorization of RhB is similar to the sum of the photocatalytic and electrolytic decolorization. Therefore the synergetic effect was not showed in pthotoelectrocatalytic reaction. $Na_{2}SO_{4}$ and NaCl showed different decolorization effect between pthotoelectrocatalytic and electrolytic/UV reaction. In the presence of the NaCl, RhB decolorization of Ru/Ti DSA electrode was higher than that of the other photoelectrode and Ti electrode. Optimum current, NaCl dosage and UV lamp power of the electrolytic/UV process (using Ru/Ti electrode) were 0.75 A, 0.5 g/L and 16 W, respectively.

• 대한환경공학회지
• /
• 제39권1호
• /
• pp.9-18
• /
• 2017

비소는 다양한 유해물질들 중 독성이 가장 크다고 알려져 있으며, 자연발생 또는 인간의 활동으로부터 비소오염이야기될 수 있다. 지하수 내 비소는 환원 환경에서 아비산염, 산화 환경에서 비산염 형태로 존재한다. 아비산염은 비산염보다 독성이 강하고 이동성이 더 크기 때문에 아비산염을 비산염으로 산화시켜 독성을 저감시키기 위한 연구가 많은 관심을 받고 있다. 본 연구에서는 비소로 오염된 지하수로부터 독성이 높은 아비산염을 독성이 낮은 비산염으로 산화시키기 위하여 자외선램프 및 자외선 LED 광원과 침철석 촉매를 이용한 광촉매 산화 공정에 대하여 연구하였다. 광산화 실험에서 광촉매로 사용된 침철석의 투여량이 0.05 g/L일 때 가장 높은 광산화 효율을 나타났다. 또한 광원의 파장별 겉보기 광산화 효율을 비교한 결과, 자외선램프가 자외선 LED에 비하여 아비산염의 산화 효율이 더 높은 것으로 나타났다. 하지만, 자외선 방사량을 기준으로 보정하면, 자외선 LED가 자외선램프보다 광산화 효율이 더 높은 것으로 평가되었다. 본 연구를 통해 침철석 광물이 존재하는 지하수 환경에서 외부로부터 다른 광촉매를 투여하지 않고 친환경적인 광산화 공정을 이용하여 비소의 독성 저감이 가능하다는 것을 알 수 있었다. 또한, 공정 또한 자외선 LED가 자외선램프의 단점을 보완할 수 있는 대체 광원으로 광산화 공정에 활용 가능하다는 것을 확인하였다.