• Clean Technology
• /
• v.21 no.3
• /
• pp.178-183
• /
• 2015

Lead molybdate (PbMoO₄) oxides were successfully synthesized using a conventional hydrothermal method and a microwave-assisted hydrothermal method. They were characterized by XRD, DRS, BET, Raman, SEM and PL. We also investigated the photocatalytic activity of these materials for the decomposition of Rhodamine B under UV-light irradiation. From XRD and Raman results, well-crystallized PbMoO₄ crystals have been successfully synthesized regardless of preparation method and had 42~59 nm particle size. The PbMoO₄ catalysts prepared using microwave-assisted process had the similar particle size and enhanced the photocatalytic activity when compared to that prepared by hydrothermal method. The PbMoO₄ catalysts prepared under the irradiation of microwave for 75 min showed the highest photocatalytic activity. The PL peaks appears at about 530 nm at all catalysts and it was also shown that the excitonic PL signal is proportional to the photocatalytic activity for the decomposition of Rhodamine B.

• Korean Journal of Optics and Photonics
• /
• v.19 no.2
• /
• pp.122-126
• /
• 2008

Dual backlight unit incorporating a single light source integrated with a beam splitting reflector was demonstrated, providing a surface light beam for both the keypad and the display section simultaneously. The reflector was realized by aligning a groove substrate with a matching cover, and a light guiding module comprising a stack of light guide panels and prism/diffuser sheets was attached to both sides of the reflector. A light emanating from the light source-placed in the middle of the substrate-undergoes a series of reflections through the reflector to reach the input of the light guiding module. Then it is transformed into a surface light beam, which is used to irradiate the keypad and display sections simultaneously. As for the accomplished dual surface light sources, the measured average luminance and the spatial luminance uniformity were respectively about $420\;cd/m^2$ and 69% for the keypad section, and $640\;cd/m^2$ and 79% for the display section.

• Clean Technology
• /
• v.16 no.1
• /
• pp.46-50
• /
• 2010

This study focuses on the removal of water-suspended toluene of a representative sick house compounds in a liquid photo-system using nanometer-sized Sn-incorporated $TiO_2$ which was synthesized by a solvothermal method. The characteristics of the synthesized Sn-$TiO_2$ were analyzed by X-ray Diffraction (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), and UV-visible spectroscopy (UV-Vis). To estimate the photocatalytic activity of Sn-$TiO_2$, the photodegradation of water-suspended toluene was performed, and the remaining concentration was determined using UV-visible spectroscopy. The water-suspended toluene photodegradation over Sn-incorporated $TiO_2$ catalyst was better than that over pure $TiO_2$ (anatase). The water-suspended toluene of 500 ppm was perfectly decomposed within 300 minutes over 0.01 mol% Sn-$TiO_2$.

• Journal of Hydrogen and New Energy
• /
• v.17 no.1
• /
• pp.55-61
• /
• 2006

신규 $Nb_2Zr_6O_{17-x}N_x$ 광촉매를 고상합성법처리(solid state synthesis) 후 암모니아가스($NH_3$)에 의한 기상처리법(ammonolysis)으로 합성하였다. 합성된 신규 광촉매 및 이를 다시 Pt 및 $RuO_2$를 도핑 하여 $H_2S$를 광분해하여 수소를 발생 실험을 수행하였다. 이 신규 oxynitrid계 광촉매는 가시광하에서 $H_2S$를 광분해하여 수소를 발생하는(Quantum yield = 13.5 %) 우수한 광촉매 활성을 보여주었다.

• Membrane Journal
• /
• v.17 no.3
• /
• pp.244-253
• /
• 2007

This research investigated the effect of a photocatalytic reaction on nanofiltration(NF) membrane fouling by natural organic matter(NOM). The photocatalytic degradation was very effective for destruction and transformation of NOM and was carried out by titanium dioxide($TiO_2$) and $TiO_2$-immobilized bead as a photocatalyst. In order to compare their phtocatalytic properties, the photocatalytic degradation of humic acid in the presence of calcium ion was used as a model reaction. After the photocatalytic degradation the membrane fouling was dramatically decreased.

• Journal of Industrial Technology
• /
• v.22 no.B
• /
• 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.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.10
• /
• pp.5304-5309
• /
• 2013

The degradation of methylethylkeone(MEK) was investigated by the continuous single module photocatalytic reactor. Operational conditions were initial concentration of MEK, intensity of photon flux, and activity change according to the long time operation. The photocatalytic degradation was decreased with the increase of MEK concentration, and the degree of decrease was larger at higher flow rate. Removal efficiency of photocatalytic reactor was decreased with the increase of reactor diameter and lamp wavelength under the same residence time condition. Continuous single module photocatalytic reactor was successfully operated without any activity drop during 120hrs operation.

• Journal of the Korean Chemical Society
• /
• v.52 no.1
• /
• pp.66-72
• /
• 2008

The photocatalytic degradation of a textile diazo dye in aqueous solution has been investigated under Solar and UV-A light. The effect of various parameters such as concentration of dye, amount of catalyst and pH on the degradation of dye has been studied. Addition of hydrogen peroxide, ammonium persulphate and isopropanol strongly influences the degradation rate. Kinetic analysis of photodegradation reveals that the degradation follows approximately pseudo first order kinetics according to the Langmuir-Hinshelwood model. Carbon dioxide, nitrate and sulphate ions have been identified as mineralisation products. The photocatalyst ZnO was found to be more efficient in UV-A light than in Solar light.

• Journal of the Korean Chemical Society
• /
• v.51 no.4
• /
• pp.318-323
• /
• 2007

Electronic photofragmentation spectrum of protonated tyrosine-alanine dipeptide ions(YAH+) was obtained in the wavenumber region of 34500~36700 cm-1 using a quadrupole ion trap time-of-flight mass spectrometer (QIT-TOFMS). YAH+ ions were produced by electrospray ionization, stored in the ion trap and then irradiated by ultraviolet laser pulses which induced photofragmentation of the ions. The electronic photofragmentation spectrum was obtained by monitoring the photodissociation yields of YAH+ ions as a function of the laser wavelength. The spectrum exhibited two broad peaks which were assigned as S1 and S2 by theoretical calculations using a time-dependent density functional method. The broad widths of the peaks in the spectrum were explained by the overlaps of the peaks originated from various conformers of YAH+ ions which were present in the gas phase at room temperature and also by the contributions of the hot bands.

• Korean Journal of Environmental Biology
• /
• v.34 no.1
• /
• pp.48-55
• /
• 2016

This study investigates the effect of effluent organic matter (EfOM) from sewage wastewater treatment plants on estrogenic activity reduction of bisphenol A (BPA) by UV photolysis. The EfOM and Suwannee River natural organic matter (SR-NOM) as reference were isolated into hydrophobic (HPO), transphilic (TPI) and hydrophilic (HPI) fractions depending on polarity. The specific ultraviolet absorbance (SUVA) analysis indicated that EfOM showed similar properties to microbially derived organic matters with low hydrophobicity, which is different from SR-NOM having high hydrophobicity. UV irradiation upto 3 hr significantly reduced SUVA values of both EfOM and SR-NOM (p<0.0001), depending on the polarity of organic matters. In the absence of organic matters, the relative estrogenic activity (REA) of BPA ($5.0{\times}10^{-5}M$) was decreased from 86% to 63% by UV photolysis (2 hr). However, the decrease of mean REA was from 68% to 37% in the presence of organic matters, which was significantly independent on the type (EfOM or SR-NOM) and polarity (HPO, TPI or HPI) of organic matters (p>0.05). As a result, the reduced REA by UV photolysis of BPA with and without organic matters was 31% and 23%, respectively, suggesting that both EfOM and SR-NOM accelerated the photolytic reduction of BPA estrogenic activity.