• 멤브레인
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• 제21권1호
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• pp.46-54
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• 2011

자연유기물을 처리하는 침지형 중공사막 정밀여과 시스템에서 $TiO_2$ 나노입자와 UV를 이용한 광촉매 반응을 적용 시 공기폭기, $TiO_2$ 농도, 용액의 pH 그리고 $Ca^{+2}$의 존재가 자연유기물에 의한 파울링에 미치는 혼합영향을 관찰하였다. 실험결과, $TiO_2$ 나노입자 없이 단순 UV의 조사만으로 자연유기물에 의한 파울링은 약 40% 정도 감소시킬 수 있었다. 또한 UV의 조사 없이 $TiO_2$ 나노입자의 교반만으로 약 25%의 파울링 감소효과를 나타내었다. 공기폭기가 광촉매 반응에 미치는 영향을 확인해 본 결과 공기폭기를 적용해 주지 않은 경우와 비교했을시 공기폭기로 인한 자연유기물의 제거효율은 약 12% 정도 향상되었다. 이는 공기폭기로 인한 분리막 표면으로부터 자연유기물의 물리적인 역수송 보다는 산소공급으로 인해 광촉매 반응이 더욱 향상된 것으로 판단된다. 공기폭기 유량, $TiO_2$ 농도, 용액의 pH 영향정도를 관찰한 결과 공기폭기가 자연유기물 파울링 감소에 미치는 영향이 가장 낮은 것으로 나타났다. 반면, 용액의 pH 경우 낮은 pH (= 4.5)에서 파울링 감소에 미치는 영향이 가장 높은 것으로 관찰되었다. 또한 $TiO_2$ 나노입자 농도가 증가할 수록 파울링 감소효과도 증가하였으며 용액의 pH를 낮출수록 파울링 감소는 증가하였다. 이는 낮은 pH에서 서로 반대전하를 지닌 자연유기물과 $TiO_2$ 나노 입자간의 정전기적인 인력이 증가하여 $TiO_2$ 나노입자 표면에서 자연유기물의 광촉매분해능이 향상된 것으로 사료된다. 또한 자연유기물 중 $Ca^{+2}$의 첨가는 상대적으로 높은 pH (= 10)에서 자연유기물과 $TiO_2$ 나노입자 사이 가교현상을 촉진시켜 $Ca^{+2}$이 첨가되지 않은 경우와 비교시 높은 파울링 감소효과와 자연유기물의 분해효과를 달성시킬 수 있었다.

• 한국표면공학회지
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• 제53권4호
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• pp.153-159
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• 2020

Photocatalytic decomposition of polyethylene film with TiO₂ nanotube powders (NTs) was investigated under UV irradiation at ambient conditions. TiO₂ NTs composed of individual nanotubes are prepared by rapid breakdown anodization technique. A comparative study on the photocatalytic decomposition of polyethylene-TiO₂ composite films prepared using TiO₂ nanoparticles (NPs) or TiO₂ NTs (NTs), respectively, was conducted under UV irradiation. Polyethylene film incorporated with TiO₂ NTs showed 26 wt% weight loss after 200 h under UV irradiation about two times faster decomposition rate than TiO₂ NPs which is attributed to large surface area of TiO₂ NTs.

• 한국축산시설환경학회지
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• 제9권2호
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• pp.85-92
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• 2003

$TiO_2$를 이용한 활성오니처리방류수의 탈색효과를 알아보고자 용량이 10$\ell$인 원통형의 시험용 pilot plant에 유속을 분당 8$\ell$로 하여 $TiO_2$첨가량, $H_2O_2$ 첨가량, UV Intensity, pH 등에 대하여 최적처리조건 구명시험을 수행하였으며 그 결과는 다음과 같다. 1. $TiO_2$를 넣지 않은 경우와 4.0g/$\ell$넣은 경우 빛의 투과율이 낮아 처리 6시간에 색도 제거율이 가장 낮았으며, $TiO_2$를 1.0g/$\ell$를 넣은 시험에서 6시간에 59.7%의 색도 제거율을 보였으며 2.0g/$\ell$에서 52.5%의 색도 제거율을 보였다. 2. pH를 5.0으로 조정한 시험구에서 처리 전색도가 655cu 이었으나 처리 1시간 후 240cu로 63.4%의 색도 제거율을 보였다. 처리 5시간 후에는 146cu로 77.7%의 색도 제거효율을 보여 가장 높은 처리효율을 보였다. 3. 산화물질인 $H_2O_2$를 주입한 농도가 높을수록 ORP는 놀은 경향이었으며, 색도 제거율은 $H_2O_2$가 200mg/$\ell$일 때 가장 높았는데, 3시간 처리 후 41.7%, 6시간 처리 후 52.5%의 색도 제거 효율을 보였다. 4. UV 365nm에서 처리 6시간에 29.4%의 색도 제거 효율을 보인데 비하여 UV 254nm에서는 50.1%의 색도 제거율을 보여 UV 254nm가 색도 제거효율이 더 높았다.

• 한국염색가공학회지
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• 제25권2호
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• pp.94-101
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• 2013

Poly(acrylonitrile) (PAN) nanofibers containing different amounts of titanium dioxide ($TiO_2$) have been prepared by electrospinning technique. Photocatalytic activity of these electrospun PAN/$TiO_2$ nanofibers and the effect of $TiO_2$ content on the photocatalytic efficiency of PAN/$TiO_2$ nanofibers have been evaluated by monitoring the photodecomposition of fluorescein dye, rhodamine B and methylene blue under UV irradiation with respect to irradiation time. Moreover, the effect of hydrogen peroxide ($H_2O_2$) on the photocatalytic behavior of PAN/$TiO_2$ nanofibers has also been investigated. The results showed that PAN/$TiO_2$ nanofibers are effective photocatalyst and their photocatalytic efficiency increases with the increase of $TiO_2$ content in the PAN/$TiO_2$ nanofibers. It is also observed that the presence of $H_2O_2$ significantly enhances the photocatalytic ability of PAN/$TiO_2$ nanofibers. The morphology and the photocatalytic behavior of the PAN/$TiO_2$ nanofibers containing different amounts of $TiO_2$ nanoparticles have been investigated by field-emission scanning electron microscopy (FE-SEM) and UV/Visible spectroscopy, respectively.

• 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.

• 한국물환경학회지
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• 제33권6호
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• pp.736-743
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• 2017

In this study, 4-nonylphenol (4-NP), an endocrine disrupting chemical, was removed by ozone treatment processes under the various experimental conditions including UV irradiation, $TiO_2$ addition. The ozone flow rate and concentration were maintained at $1.0L{\cdot}min^{-1}$ and $70{\pm}5mg{\cdot}L^{-1}$. The pH, COD and TOC of the samples were obtained every 10 minutes for 60 minutes in laboratory scale batch reactor. We found that the combination of UV irradiation and $TiO_2$ addition for ozonation improves the removal efficiency of COD and TOC in 4-NP aqueous solution. In case of the $O_3/UV/TiO_2$ system, COD and TOC were greatly reduced to 85.3 ~ 94.0% and 89.2 ~ 97.2%, respectively. 4-NP degradation rate constants, $k_{COD}$ and $k_{TOC}$, were calculated based on the COD and TOC values. Significantly, $k_{COD}$ and $k_{TOC}$ were improved in the $O_3/UV/TiO_2$ treatment process compared with single $O_3$ process, because the oxidation and the mineralization of 4-NP were increased by generating of the hydroxyl radical. The $k_{COD}$ and $k_{TOC}$ were obtained to be $5.81{\times}10^{-4}{\sim}10.8{\times}10^{-4}sec^{-1}$ and $11.9{\times}10^{-4}{\sim}19.4{\times}10^{-4}sec^{-1}$ in the $O_3/UV/TiO_2$ process. Activation energy ($E_a$) of ozone oxidation reaction based on $k_{COD}$ and $k_{TOC}$ were increased in order of $O_3/UV/TiO_2$ < $O3/UV$ < $O_3/TiO_2$ < $O_3$ process. It was confirmed that the addition of $TiO_2$ and UV irradiation to the ozone oxidation reaction significantly reduced the $E_a$ value and the degradation of 4-NP.

• Elastomers and Composites
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• 제44권4호
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• pp.408-415
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• 2009

졸-겔 방법을 사용하여 Fe-ACF/$TiO_2$ 복합체 광촉매를 제조하였다. 여러 가지 철 전구체를 사용하여 세가지 Fe-ACF/$TiO_2$ 복합체를 제조하고 BET, SEM, XRD 및 EDX를 사용하여 특성화 하였다. UV 조사에서 Rh.B 용액의 분해에 의거하여 Fe-ACF/$TiO_2$ 복합체의 광촉매 특성을 파악 하였다. 실험 결과로부터, Fe-ACF/$TiO_2$ 복합체는 ACF/$TiO_2$ 복합체 보다 Rh.B의 제거 효과가 더 우수함을 나타내었다. 또한 여러 가지 Fe 전구체 사용으로 인한 Fe 원소의 포토-펜톤 효과는 다르게 나타났다. $FeCl_3$을 사용하여 제조된 Fe-ACF/$TiO_2$ 복합체는 가장 우수한 포토-펜톤 효과를 나타내었고, pH 변화에 의존하여 Rh.B 용액 분해에 대하여 영향을 주었다.

• 한국환경과학회지
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• 제13권10호
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• pp.921-928
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• 2004

The photocatalytic decolorization of Rhodamine B (RhB) was studied using immobilized $TiO_2$ and fluidized bed reactor. Immobilized $TiO_2$(length: 1$\~$2 mm, width: 1$\~$3 mm, thickness: 0.5$\~$2 mm) onto silicone sealant was employed as the photocatalyst and a 30 W germicidal lamp was used as the light source and the reactor volume was 4.8 L. The effects of parameters such as the amounts of photocatalyst, initial concentration, initial pH, superficial velocity, $H_2O_2$ and anion additives. ($NO_3^{-},\;SO_4^{2-},\;Cl^{-},\;CO_3^{2-}$) The results showed that the optimum dosage of the immobilized $TiO_2$ were 87.0 g/L. Initial removal rate of RhB of the immobilized $TiO_2$ was 1.5 times higher than that of the powder $TiO_2$ because of the adsorption onto the surface of immobilized $TiO_2$ In the conditions of acidic pH, initial reaction rate was increased slowly and reaction time was shorted. The effect of anion type on the reaction rate was not much.

• Bulletin of the Korean Chemical Society
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• 제31권2호
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• pp.344-350
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• 2010

The improved photocatalytic performance of a carbon/$TiO_2$ composite was studied for the Bisphenol A (BPA) decomposition. Titanium tetraisopropoxide (TTIP) and a rice husk from Korea were heterogeneously mixed as the titanium and carbon sources, respectively, for 3 h at room temperature, and then thermally treated at $600^{\circ}C$ for 1 h in $H_2$ gas. The transmission electron microscopy (TEM) images revealed that the bulk carbon partially covered the $TiO_2$ particles, and the amount that was covered increased with the addition of the rice husk. The acquired carbon/$TiO_2$ composite exhibited an anatase structure and a novel peak at $2{\theta}=32^{\circ}$, which was assigned to bulk carbon. The specific surface area was significantly enhanced to 123~164 $m^2/g$ in the carbon/$TiO_2$ composite, compared to $32.43m^2/g$ for the pure $TiO_2$. The X-ray photoelectron spectroscopy (XPS) results showed that the Ti-O bond was weaker in the carbon/$TiO_2$ composite than in the pure $TiO_2$, resulting in an easier electron transition from the Ti valence band to the conduction band. The carbon/$TiO_2$ composite absorbed over the whole UV-visible range, whereas the absorption band in the pure$TiO_2$ was only observed in the UV range. These results agreed well with an electrostatic force microscopy (EFM) study that showed that the electrons were rapidly transferred to the surface of the carbon/$TiO_2$ composite compared to the pure $TiO_2$. The photocatalytic performance of the BPA removal was optimized at a Ti:C ratio of 9.5:0.5, and this photocatalytic composite completely decomposed 10.0 ppm BPA after 210 min, whereas the pure $TiO_2$ achieved no more than 50% decomposition under any conditions.

• 한국재료학회지
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• 제26권2호
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• pp.73-78
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• 2016

$TiO_2$ nanoparticles were synthesized by a sol-gel process using titanium tetra isopropoxide as a precursor at room temperature. Ag-doped $TiO_2$ nanoparticles were prepared by photoreduction of $AgNO_3$ on $TiO_2$ under UV light irradiation and calcinated at $400^{\circ}C$. Ag-doped $TiO_2$ nanoparticles were characterized for their structural and morphological properties by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The photocatalytic properties of the $TiO_2$ and Ag-doped $TiO_2$ nanoparticles were evaluated according to the degree of photocatalytic degradation of gaseous benzene under UV and visible light irradiation. To estimate the rate of photolysis under UV (${\lambda}=365nm$) and visible (${\lambda}{\geq}410nm$) light, the residual concentration of benzene was monitored by gas chromatography (GC). Both undoped/doped nanoparticles showed about 80 % of photolysis of benzene under UV light. However, under visible light irradiation Ag-doped $TiO_2$ nanoparticles exhibited a photocatalytic reaction toward the photodegradation of benzene more efficient than that of bare $TiO_2$. The enhanced photocatalytic reaction of Ag-doped $TiO_2$ nanoparticles is attributed to the decrease in the activation energy and to the existence of Ag in the $TiO_2$ host lattice, which increases the absorption capacity in the visible region by acting as an electron trapper and promotes charge separation of the photoinduced electrons ($e^-$) and holes ($h^+$). The use of Ag-doped $TiO_2$ nanoparticles preserved the option of an environmentally benign photocatalytic reaction using visible light; These particles can be applicable to environmental cleaning applications.