• Applied Chemistry for Engineering
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• v.7 no.4
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• pp.750-756
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• 1996

$TiO_2$ was dispersed in zeolite and glass filter by soaking them in isopropanol solution of titanium tetraisopropoxide and drying in the air, followed by calcination at $500^{\circ}C$. The analysis of chlorothalnoil was carried out by gas chromatograph with an electron capture detector. Chlorothalnoil was degraded photocatalytically over the matrix-supported $TiO_2$ efficiently and could be completely photodegraded after 3hrs. Production were 5.0ppm of $Cl^-$ for $TiO_2$ supported zeolite, 7.5ppm of $Cl^-$ for $TiO_2$ supported glass filter and 2.0ppm of $Cl^-$ for $TiO_2$ powder. But, $CN^-$ was lower than the detection limit irrespective of matrices.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.4
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• pp.491-496
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• 2017

The hydrogen($H_2$) is promising energy carrier of renewable energy in the microgrid system such as small village and military base due to its high energy density, pure emission and convenient transportation. $H_2$ can be generated by photocatalytic water splitting, gasification of biomass and water electrolysis driven by solar cell or wind turbine. Solid oxide electrolysis cells(SOECs) are the most efficient way to mass production due to high operating temperature improving the electrode kinetics and reducing the electrolyte resistance. The SOECs are consist of nickel-yttria stabilized zirconia(NiO-YSZ) fuel electrode / YSZ electrolyte / lanthanum strontium manganite-YSZ(LSM-YSZ) air electrode due to similarity to Solid Oxide Fuel Cells(SOFCs). The Ni-YSZ most widely used fuel electrode shows several problems at SOEC mode such as degradation of the fuel electrode because of Ni particle's redox reaction and agglomeration. Therefore Ni-YSZ need to be replaced to an alternative fuel electrode material. In this study, We studied on the Double perovskite $PrBrMnO_{5+{\delta}}$(PBMO) due to its high electric conductivity, catalytic activity and electrochemical stability. PBMO was impregnated into the scaffold electrolyte $La_{0.8}Sr_{0.2}Ga_{0.85}Mg_{0.15}O_{3-{\delta}}$(LSGM) to be synthesized at low temperature for avoiding secondary phase generated when it exposed to high temperature. The Half cell test was conducted at SOECs and SOFCs modes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.2
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• pp.1579-1584
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• 2015

In photocatalytic reaction, the doping of metal matter can alter the titania surface properties. As such the metal matter can increase the rate of the reaction. The influence of metal doping and calcination condition of $TiO_2$ photocatalyst was investigated at the batch-type photoreactor. Several metal matters were doped to the $TiO_2$ catalyst to improve photodegradation efficiency. During the experiments, water content was 3wt%, and reactor temperature was $40^{\circ}C$. Palladium-doped $TiO_2$ was found to be the best, where as platinum or tungsten-added also showed good results. Additional doping of platinum or tungsten on Pd/$TiO_2$ had no increase on the removal efficiency. To obtain proper calcination condition, various experiments about calcination temperature and time were carried out. As a result, the optimum calcination condition was temperature of $400^{\circ}C$, time of 1 hour.

• Journal of Microbiology and Biotechnology
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• v.32 no.9
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• pp.1195-1208
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• 2022

Silver nanoparticles (AgNPs) have potential applications in medicine, photocatalysis, agriculture, and cosmetic fields due to their unique physicochemical properties and strong antimicrobial activity. Here, AgNPs were synthesized using actinobacterial SL19 strain, isolated from acidic forest soil in Poland, and confirmed by UV-vis and FTIR spectroscopy, TEM, and zeta potential analysis. The AgNPs were polydispersed, stable, spherical, and small, with an average size of 23 nm. The FTIR study revealed the presence of bonds characteristic of proteins that cover nanoparticles. These proteins were then studied by using liquid chromatography with tandem mass spectrometry (LC-MS/MS) and identified with the highest similarity to hypothetical protein and porin with molecular masses equal to 41 and 38 kDa, respectively. Our AgNPs exhibited remarkable antibacterial activity against Escherichia coli and Pseudomonas aeruginosa. The combined, synergistic action of these synthesized AgNPs with commercial antibiotics (ampicillin, kanamycin, streptomycin, and tetracycline) enabled dose reductions in both components and increased their antimicrobial efficacy, especially in the case of streptomycin and tetracycline. Furthermore, the in vitro activity of the AgNPs on human cancer cell lines (MCF-7, A375, A549, and HepG2) showed cancer-specific sensitivity, while the genotoxic activity was evaluated by Ames assay, which revealed a lack of mutagenicity on the part of nanoparticles in Salmonella Typhimurium TA98 strain. We also studied the impact of the AgNPs on the catalytic and photocatalytic degradation of methyl orange (MO). The decomposition of MO was observed by a decrease in intensity of absorbance within time. The results of our study proved the easy, fast, and efficient synthesis of AgNPs using acidophilic actinomycete SL19 strain and demonstrated the remarkable potential of these AgNPs as anticancer and antibacterial agents. However, the properties and activity of such particles can vary by biosynthesized batch.

• Journal of the Korean Applied Science and Technology
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• v.39 no.1
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• pp.34-41
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• 2022

As the use of chemical products increases in daily life, the removal of dye waste has also emerged as an important environmental issue. This dye waste can be decomposed using a photocatalyst, and the photocatalyst can be synthesized very cost-effectively by using the sol-gel technology. The sol-gel technology is not only very useful for nanoscale film formation, but also can simply form multilayer structures. Using a multiple spin coating method, in this study, a ZnO film with a multilayered structure (3 layers, 5 layers) was formed by using zinc oxide (ZnO), which is effective in decomposing various dyes. For performance comparison, a ZnO film having a single layer structure by a single spin coating method was prepared as a control. Structural and elemental analysis of ZnO film was performed using an X-ray diffraction analyzer and an energy dispersive X-ray spectrometer. A nanowire-like surface morphology could be observed through a scanning electron microscope. Additionally, UV-Vis spectrophotometer was used to measure the absorbance of UV light. The ZnO film with a five-layer structure degraded the simulated methylene blue by 49% more than the ZnO film with a single-layer structure. In conclusion, it was found that ZnO having a multilayered structure is useful as a photocatalyst that decomposes methylene blue dye more effectively.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.4
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• pp.765-773
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• 2000

The degradation of humic acid using $TiO_2$ coatings was studied, $TiO_2$ coatings were prepared by dip-coating method. Sol solutions for coating were prepared by mixing the gel, which can be produced by the reaction of $TiOCl_2$ and $NH_4OH$ solution, and hydrogen peroxide solution, and hydrolysis of titanium tetraisopropoxide (TTIP). It was shown from XRD that coatings from sol aged at $100^{\circ}C$ for 18h with titanium peroxo solution were crystallized to anatase in the range of temperatures of $25^{\circ}C$ to $500^{\circ}C$. In contrast, those coated from TTIP were crystallized to anatase at temperature above $400^{\circ}C$. So the sols originated from $TiCl_4$ can be applied for not only on the heat-resistance substrates but on the plastic substrates. Thickness and the quality of the films were dependent on the withdrawing speed, the concentration of sol, and the number of coating. The films showed various interference colors depending on the thickness of them. In the case that the films coated 2 times at withdrawing speed of 2.5cm per minute by 0.2M sol, the films had a transparent light blue color with thickness of around 50nm. It was known from the result of photo-degradation by $TiO_2$ coatings using humic acid that the removal efficiency of $COD_{cr}$ was over 85% after illumination of $UV/H_2O_2$ for 40min. and that of UV/VIS absorbable materials was over 95%.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.12
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• pp.907-912
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• 2011

Development of visible light responsive photocatalysts is a promising research area to facilitate utilization of solar energy for hydrogen production via photocatalytic water splitting. In this study two groups of samples, nitrogen (N)-doped niobium pentoxide ($Nb_2O_5$) and titanium dioxide ($TiO_2$) ($Nb_2O_5-N$, $HNb_3O_8-N$, $TiO_2-N$) and N-undoped ones ($Nb_2O_5$ and $TiO_2$) were tested. In order to utilize visible light, nitrogen atoms were doped in selected photocatalysts by using urea. A shift of the absorption edges of the Ndoped samples in the visible light region was observed. Under visible light irradiation, N-doped samples were more prominent photocatalytic activities than the N-undoped samples. Specifically, 99.7% of rhodamine B (RhB) was degraded after 60 minutes of visible light irradiation with $TiO_2-N$. Since $TiO_2-N$ shows the highest activity of RhB degradation, it was supposed to generate the highest current response. However, $HNb_3O_8-N$ showed the highest current response ($63.7mA/cm^2$) than $TiO_2-N$. More interestingly, when we compare the hydrogen production, $Nb_2O_5-N$ produced $19.4{\mu}mol/h$ of hydrogen.

• Korean Journal of Food Science and Technology
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• v.47 no.6
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• pp.733-737
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• 2015

For testing the ultraviolet (UV)-blocking property of functional films coated with Nano-$TiO_2$ particles, UV-Vis spectra of oriented polypropylene (OPP) films uncoated and coated with $TiO_2$ of 3% and 5% in Polyurethane (PU) and polyvinyl butyral (PVB)-Cellulose binders were measured. The result of UV-Vis analyses showed that the film coated with 5% $TiO_2$ in PVB binders had a significant effect on UV protection of 90% compared with the film uncoated. Also The result of The photodegradation of methylene blue (MB), OPP films coated with 5% in both PU and PVB binders had a high photocatalytic activity for MB degradation. To evaluate the effect of the developed functional film coated with Nano-$TiO_2$ particles, fresh soybean sprouts were used. Nano-$TiO_2$ coated film was observed to decompose the off-flavor produced by soybean sprouts within packages during distribution, but uncoated film did not. Therefore, Nano-$TiO_2$ coated film package could give the greatest effect in extending the shelf life of soybean sprouts.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.1
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• pp.59-66
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• 2005

[ $TiO_2$ ] was deposited by DC magnetron sputtering on glass surface under various sputtering parameters such as discharge power($0.6{\sim}5.2\;kW$, substrate temperature($R.T{\sim}350^{\circ}C$), Ar and $O_2$ flow ratio with $0{\sim}50\;sccm$($Ar+O_2$ 90 sccm) and about 1 mtorr of pressure. TiO-N thin film was prepared under same sputtering conditions for $TiO_2$ thin film except flow ratio($Ar+O_2+N_2$ 90 sccm). The sheet resistance of thin films deposited under these parameters was measured to analyze electronic characteristic and thin film's thickness(${\alpha}$-step), surface roughness(AFM) and formation construction(FE-SEM, XRD) were also measured to draw optimal sputtering parameters. In order to evaluate photo-activity of thin film($TiO_2$, TiO-N) made in optimal parameters for removal of pollutants, toluene among VOCs and Suncion Yellow among reactive dyes were chosen to probe organic compounds for photo-degradation. It was shown that the photo-catalytic thin films had a significant photo-activation for the chosen contaminants and especially TiO-N thin film showed maximum efficiency of 33% for toluene(5 ppm) removal in visible-light range.

• Applied Chemistry for Engineering
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• v.28 no.6
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• pp.705-713
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• 2017

A novel material, $Bi_2WO_6-GO-TiO_2$ composite, was successfully synthesized using a facile hydrothermal method. During the hydrothermal reaction, the loading of $Bi_2WO_6$ and $TiO_2$ nanoparticles onto graphene sheets was achieved. The obtained $Bi_2WO_{6-GO-TiO2}$ composite photo-catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), Raman spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (UV-vis-DRS), and X-ray photoelectron spectroscopy (XPS). The $Bi_2WO_6$ nanoparticle showed an irregular dark-square block nanoplate shape, while $TiO_2$ nanoparticles covered the surface of the graphene sheets with a quantum dot size. The degradation of rhodamine B (RhB), methylene blue trihydrate (MB), and reactive black B (RBB) dyes in an aqueous solution with different initial amount of catalysts was observed by UV spectrophotometry after measuring the decrease in the concentration. As a result, the $Bi_2WO_6-GO-TiO_2$ composite showed good decolorization activity with MB solution under visible light. The $Bi_2WO_6-GO-TiO_2$ composite is expected to become a new potential material for decolorization activity. Photocatalytic reactions with different photocatalysts were explained by the Langmuir-Hinshelwood model and a band theory.