• Proceedings of the Korean Environmental Sciences Society Conference
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• 1997.04a
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• pp.61-63
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• 1997

• Particle and aerosol research
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• v.6 no.4
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• pp.165-172
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• 2010

Titania is widely used as an effective photocatalyst for the photodegradation of environmental pollutants in air. In this study, novel N-doped $ZrO_2/TiO_2$ photocatalysts were synthesized via sol-gel method and characterized by UV-Vis spectrophotometer, transmission electron microscope, and X-ray diffractometer. N-doped $ZrO_2/TiO_2$ photocatalysts were nano-sized with an average particle size of about 20 nm. The XRD pattern of N-doped $ZrO_2/TiO_2$ photocatalysts showed both anatase and rutile phases. The photocatalytic activity of N-doped $ZrO_2/TiO_2$ photocatalysts was evaluated by degradation of NO under UV and visible light irradiation at various parameters such as amount of photocatalyst, concentration of NO, and intensity of light. The photocatalytic activity of N-doped $ZrO_2/TiO_2$ photocatalysts was effective for the enhancement of the degradation of NO and higher than that of $TiO_2$ photocatlysts under UV and visible light irradiation.

• Journal of the Korean Ceramic Society
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• v.49 no.5
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• pp.461-468
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• 2012

This study focuses on the difference of photocatalytic activity depending on crystal structure type of nanoparticles ($TiO_2$) and nanotubes (TNT). The photodecomposition of 2-chlorophenol on the synthesized $TiO_2$, Sn-impregnated $TiO_2$, TNT, and Snimpregnated TNT were evaluated. The characteristics of the synthesized photocatalyts, TNT, Sn/TNT, $TiO_2$, and Sn/$TiO_2$ were analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-Visible spectroscopy (UV-Vis), and cyclic voltammeter (CV). The water-suspended 2-chlorophenol photodegradation over $TiO_2$ (anatase structure) catalyst was better than that over pure TNT. Particularly, the water-suspended 2-chlorophenol of 10 ppm was perfectly decomposed within 4 h over Sn/$TiO_2$ photocatalyst.

• Advances in materials Research
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• v.6 no.1
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• pp.1-12
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• 2017

The aim of the work was to evaluate the effect of ultraviolet-ozone ($UV-O_3$) irradiation with different times on the structure and thermal properties of hydroxypropyl methylcellulose (HPMC) in the form of a thin film to be used as bioequivalent materials according to their important broad practical and medical applications. HPMC thin films were exposed to $UV-O_3$ radiation in air at a wavelength of 184.9 nm.The beneficial effects of this treatment on the crystallinity and amorphousity regions were followed by X-ray diffraction technique and FTIR spectroscopy. Differential scanning calorimetry, thermogravimetric and differntial thermal analyses were used in order to study the thermal properties of HPMC samples following the process of photodegradation. The obtained results indicated that the rate of degradation process was increased with increasing the exposure time. Variations in shape and area of the thermal peaks were observed which may be attributed to the different degrees of crystallinity after exposing the treated HPMC samples. This meant a change in the amorphousity of the treated samples, the oxidation of its chemical linkages on its surface and its bulk, and the formation of free radical species as well as bond formation.

• Journal of the Korean Applied Science and Technology
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• v.23 no.2
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• pp.153-159
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• 2006

The photocatalytic degradation of methylene blue(MB) was investigated using $TiO_2$ as photocatalyst and UV radiation. $TiO_2$ supported with activated carbon(AC) was prepared by SOL-GEL method and depended on several parameters such as the mass ratio of $TiO_2/AC$, pH and experimental time. The presence of the anatase and rutile crystal phase was determined by XRD analyses of the prepared $TiO_2$. The degradation of MB with $TiO_2/AC$ was about 20% higher than that of AC alone. A variation of photodegradation was negligible under UV radiation conditions ( ${\geq}$ 40W). It was experimentally showed that the photodegradation rate was increased with increasing the amount of photocatalyst. The optimal catalyst was prepared by impregmation of $5wt%-TiO_2$ with AC and was calcined at $300^{\circ}C$, and showed about 99% removal efficiency for 3hrs.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1881-1884
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• 2003

In this experiment, the oxidations of p-Xylene (140-180 ppmv), one of the air pollutants as a VOC, using $UV/TiO_2$ photocatalyst is studied. In order to increase the specific surface area, the filter is coated by nano $TiO_2$ particles. The photodegradation system consists of a VOCs generator, a photocatalyst filter and a measuring equipment. Illumination is generally provided by two of 20 W black light lamps with 380 nm of wavelength. The filter coated by nano $TiO_2$ particles has a passing efficiency over 80% but a pressure drop of 9.0 $mmH_2O$ at 0.45 cm/s. The filter endurance is better than activated carbon at the same pressure drop.

• Journal of Photoscience
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• v.3 no.3
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• pp.167-169
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• 1996

Absorption of UV light induces photocleavage of polymer chains to produce free radicals which initiate photodegradation of the polymer molecules. Discoloration, cracking of surface, stiffening, and decreasing of mechanical properties of polymeric products occur as a result of photodegradation of the polymers. Photostabilizers are added to the polymer systems in order to minimize the unwanted effects of UV light. It is well known that Hindered Amine Light Stabilizers (HALS) are one of the most effective photostabilizer for polymers.' HALS have been used in a large number of commercial polymers and predominantly used in styrenic and engineering plastics. They are efficient and cost-effective in many applications despite their high prices. However, low molecular weight HALS vaporize easily, emitting harmful amines, and have poor extraction resistance, decreasing their photostabilization effect. They also decompose during processing and migrate within the polymers resulting in deposition on the polymer surfaces called 'blooming". These drawbacks of low molecular HALS can be overcome by use of the polymeric HALS. We have been studying photochemical reactions of the polymer systems. The present paper reports the preparation of a new polymeric photostabilizer containing HALS groups and their stabilization effects on photooxidation of polystyrene. The synthetic scheme for the preparation of polymeric photostabilizers containing HALS groups were shown at Scheme 1. N-[(Chloroformyl) phenyl]maleimide (CPMI) and N-[4-(chlorocarbonyl) phenyl]maleimide (CPMIC) were prepared by the known procedure. N[4-N'-(2,2,6,6-tetramethyl-4-piperidinyl)aminocarbonyl-phenyl] maleimide (TMPI) was prepared by the reaction of CPMI with 4-amino-2,2,6,6-tetramethylpiperidine (ATMP).

• Elastomers and Composites
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• v.50 no.1
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• pp.7-12
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• 2015

The $BaCrO_4$ nanoparticles were synthesized from a 0.1 M $K_2CrO_4$ and 0.1 M $BaCO_3$ solution with stirring for 10 h. The product was washed several times with acetone and heated to $700^{\circ}C$ for 6 h. At that time, the color of mixture was a greenish yellow. The graphene/$BaCrO_4$ nanocomposites were prepared with graphene and $BaCrO_4$ nanoparticles by stirring in tetrahydrofuran and heated in an electric furnace at $700^{\circ}C$ for 2 h. The $BaCrO_4$ nanoparticles, graphene/$BaCrO_4$ and heated graphene/$BaCrO_4$ nanocomposites were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The graphene/$BaCrO_4$ nanocomposites and heated graphene/$BaCrO_4$ nanocomposites were evaluated as a photocatalyst and discussed about kinetics study for the degradation of organic dyes, such as methylene blue and rhodamine B under ultraviolet light irradiation at 254 nm.

• Journal of Food Hygiene and Safety
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• v.19 no.2
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• pp.97-103
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• 2004

The present study was performed to investigate photodegradation rate constants and degradation products of piperophos by the USEPA method. The pesticide was very stable in 16 days exposure of sunlight from October 3 to 22, 2003 and humic acid had no sensitizing effect on the photolysis of each pesticide in sunlight. In the UV irradiation test, piperophos was rapidly degraded as increasing UV intensity. In case of UV irradiation with TiO$_2$ and with TiO$_2$ powder amount, degradation of piperophos was slower than UV irradiation. In order to identify photolysis product, the extracts of degradation product was analyzed by GC/MS. The mass spectrum of photolysis product of piperophos was at m/z 166. It was suggested that the photolysis products of piperophos was O, O-dipropyl phosphorodithioate.

• Journal of the Korean Chemical Society
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• v.19 no.6
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• pp.454-462
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• 1975

The photodegradation of polystyrene and polyethylene was studied utilizing several additives to promote photooxidation. Polymer films with small amount of additives were irradiated with ultraviolet lamps in Rayonet Photochemical Reactor. The progress of photodegradation was followed by measuring the intensities of carbonyl and hydroxyl stretching bands in infrared spectra as well as the viscosity changes. It was found that the increase of carbonyl or hydroxyl peaks was proportional to the decrease of the molecular weight of polymers under study. Iron(II, III) complexes of dithiocarbamate and their analogs showed good results.