• Korean Journal of Materials Research
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• v.19 no.9
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• pp.481-487
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• 2009

The photocatalysts of Fe-ACF/$TiO_2$ compositeswere prepared by the sol-gel method and characterized by BET, XRD, SEM, and EDX. It showed that the BET surface area was related to adsorption capacity for each composite. The SEM results showed that ferric compound and titanium dioxide were distributed on the surfaces of ACF. The XRD results showed that Fe-ACF/$TiO_2$ composite only contained an anatase structure with a Fe mediated compound. EDX results showed the presence of C, O, and Ti with Fe peaks in Fe-ACF/$TiO_2$ composites. From the photocataytic degradation effect, $TiO_2$ on activated carbon fiber surface modified with Fe (Fe-ACF/$TiO_2$) could work in the photo-Fenton process. It was revealed that the photo-Fenton reaction gives considerable photocatalytic ability for the decomposition of methylene blue (MB) compared to non-treated ACF/$TiO_2$, and the photo-Fenton reaction was improved by the addition of $H_2O_2$. It was proved that the decomposition of MB under UV (365 nm) irradiation in the presence of $H_2O_2$ predominantly accelerated the oxidation of $Fe^{2+}$ to $Fe^{3+}$ and produced a high concentration of OH radicals.

• Korean Journal of Materials Research
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• v.26 no.8
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• pp.406-411
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• 2016

In order to reuse the photocatalyst and enhance the photolysis efficiency, we have used atmospheric pressure dielectric barrier discharge (APDBD) to clean and activate $TiO_2$ powder. The photocatalytic activity of the $TiO_2$ powder before and after APDBD treatment was evaluated by the degradation of methylene blue (MB) in aqueous solution. The apparent reaction rate constant of photolysis of the first sample of reused $TiO_2$ cleaned by APDBD improved to a level up to 0.32h-1 higher than the 30 % value of the initial $TiO_2$ powder. As the number of photolysis reactions and APDBD cleanings increased, the apparent rate constants gradually decreased; however, the fourth photolysis reaction still showed a value that was greater than 10% of the initial value. In addition, APDBD treatment enhanced the process by which $TiO_2$ effectively adsorbed MB at every photolysis stage.

• Journal of Environmental Science International
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• v.16 no.4
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• pp.433-440
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• 2007

The photodegradation and by-products of the gaseous toluene with $TiO_2$ (P25) and short-wavelength UV ($UV_{254+185nm}$) radiation were studied. The toluene was decomposed and mineralized efficiently owed to the synergistic effect of photochemical oxidation in the gas phase and photocatalytic oxidation on the $TiO_2$ surface. The toluene by the $UV_{254+185nm}$ photoirradiated $TiO_2$ were mainly mineralized $CO_2$ and CO, but some water-soluble organic intermediates were also formed under severe reaction conditions. The ozone and secondary organic aerosol were produced as undesirable by-products. It was found that wet scrubber was useful as post-treatment to remove water-soluble organic intermediates. Excess ozone could be easily removed by means of a $MnO_2$ ozone-decomposition catalyst. It was also observed that the $MnO_2$ catalyst could decompose organic compounds by using oxygen reactive species formed in process of ozone decomposition.

• Journal of the Korean Ceramic Society
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• v.47 no.2
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• pp.169-176
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• 2010

The Fe-treated CNT/$TiO_2$ photocatalysts mixed with anatase and rutile phase have been developed for the decomposition of non-biodegradable different organic dyes like methylene blue (MB), rhodamine B (Rh.B), and methyl orange (MO) in two conditions as ultraviolet and visible light respectively. The results indicate that all the Fe-CNT/$TiO_2$ composites proved to be more efficient photocatalysts since degradation of MB at higher reaction rates, tthe decomposition rate of different dyes increases with an increase of $Fe^{3+}$ concentration in composites the highest rate of decomposition of different dyes was noted under UV irradiation. These results can indicate that the large CNT network is facilitate the electron transfer and strongly adsorb dye molecules on the texted photocatalysts, iron is reactive in the photo-Fenton process resulting in high production of OH radicals and also high activity of the photocatalyst. And Fe particles can generate more photoinduced electrons to conduction band of $TiO_2$ under visible light irradiation. The composites of Fe-CNT/$TiO_2$ photocatalysts synthesized by a sol-gel method were characterized by BET, TEM, SEM, XRD and EDX.

• Journal of environmental and Sanitary engineering
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• v.20 no.4 s.58
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• pp.45-50
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• 2005

Titania gel formations were prepared by sol-gel method using titanium(IV) chloride $(TiCl_4)$, and its characteristics were analyzed by varying the $epoxide/TiCl_4$ ratio and the amount of water In the end, titania $(TiO_2)$ aerogel were prepared using supercritical drying process. VOCs such as benzene, toluene, and m-xylene (BTX) were oxidized using prepared titania aerogel and commercially available $TiO_2$, and its performance was compared. The surface area, pore volume, and average pore diameter of 1,2-epoxybutane are significantly smaller than the propylene oxide. And the titania aerogels with 6 moi of epoxides have high surface areas, pore volumes, and average pore diameters. As a result of photo-oxidation, conversion of benzene was reached about $70\%$, and other reactants were reached about $60\%$ similarly. The conversion of BTX was increased as inlet concentration decreased. The reactivity of titania calcined at $600^{\circ}C$ was greater than $400^{\circ}C$ and $800^{\circ}C$. Water is required as a reactants for the oxidation of VOCs, and the continuous consumption of hydroxyl radicals required replenishments to maintain catalyst activity. The activity ratio increased with increasing reaction time when enough amount of water was present in the reactor.

• Environmental Analysis Health and Toxicology
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• v.19 no.3
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• pp.271-278
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• 2004

Epoxy resins are mostly used as a molding material for drinking water tank. Bisphenol A is used at a constituent material for epoxy resins and is widely suspected to act as an endocrine disrupter. In this study, we investigated embryo hatching in zebrafish reared in water undergone leaching process of expoxy resin, and found a decreased survival rate. Bisphenol A eluted from epoxy resin in drinking water tank was completely degraded by TiO$_2$ photocatalysis. We detected 7.8 ng/ml of bisphenol A in epoxy resin tank, and observed that the concentration was undetectable after 48h photocatalysis over TiO$_2$. There was no toxicity in hatching rates in zebrafish and morphogenesis after photocatalysis. The effect of TiO$_2$ photocatalytic reactions on the catalase activities in the f]y stage of zebrafish was also examined. At 1 week post hatching, cataiase activities were higher both in the group of epoxy resin with 48 h TiO$_2$ photocatalysis and in the TiO$_2$ photocatalysis for 48 hours were higher than control group. However catalase activities of the treatment group of epoxy resin by TiO$_2$ photocatalysis for 48 hours were similar to control in 5 weeks post hatching fries. In conclusion, the toxicity of TiO$_2$ photocatalysis was not observed in this zebrafish.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.3
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• pp.411-419
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• 2004

Titania particles are widely used as a photocatalyst to treat various contaminants in air and water. Titania particles were formed by vapor-phase oxidation of titanium tetraisopropoxide (TTIP) in a tube furnace between 773 and 1,273 K. The effect of process variables such as furnace temperature, flow rate of carrier air, and flow rate of sheath air on powder size and phase characteristics was investigated using a scanning mobility particle sizer (SMPS), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The size distribution of synthesized titania particles was characterized with mode diameter and peak concentration. The mode diameter ranging from 20 to 80 nm decreased with increasing flow rates of sheath air and carrier air, and increased with increasing furnace temperature. The peak concentration increased with increasing flow rates of sheath air and carrier air The best synthetic condition for high production rate can be derived from the experimental data set represented by mode diameter and peak concentration. The crystal structure of synthesized titania particles was found to be anatase phase, ensuring high photocatalytic potential.

• International Journal of Advanced Culture Technology
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• v.3 no.1
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• pp.13-20
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• 2015

The self-cleaning properties of nano-zinc oxide on cotton fabrics have been investigated. The cotton fabric has been prepared by pad-dry method. The nano-zinc oxide was encapsulated in the polystyrene particle by mini-emulsion process prior used. The loading amount of zinc oxide particles into the mini-emulsion were various from 1% wt to 40%wt. The particles sizes of ZnO-encapsulated polystyrene mini-emulsion were determined using dynamic light scattering. It was showed that the particle size of the mini-emulsion was in the range of 124-205 nm. The topography and morphology of ZnO-encapsulated polystyrene which coated on cotton fabrics was observed using scanning electron microscopy. The crystal structure of ZnO-coated on cotton fabrics was explored by X-ray diffraction spectroscopy. The photocatalytic activities of zinc oxide were present through the self-cleaning properties. The presents of the zinc oxide on cotton fabrics significantly showed the improving of the self-cleaning properties under UV radiation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.12a
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• pp.39-42
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• 2006

Titania sols or powders were are very promising materials for environment as photocatalyst. The band gap energy of $TiO_2$ has been known to be 2.8 to 3.2 eV. But the measuring system of its band gap is usually depend on absorption properties. Thus, in this study, absorption properties of $TiO_2$ sols prepared by hydrothermal process were researched with the effect of various particle sizes and concentrations. The mean particle size in $TiO_2$ sols increased as 15 nm to 60 nm, absorption graph measured by UV-Vis spectrometer shows to move red-shift. When dilute solution added with $2^n$ in $TiO_2$, the band gap energy increases as linear function.

• Advances in concrete construction
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• v.11 no.4
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• pp.307-314
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• 2021

Activated hwangtoh (ACT) is a natural resource abundant in South Korea, approximately 15.0% of soil. It is an efficient mineral admixture that has activated pozzolanic properties through high-temperature heating and rapid cooling. The purpose of this study is to improve a curb mixture that can reduce NOx outside and investigate durability performance. To this end, mortar curb specimens were manufactured by replacing OPC with ACT. The ACT substitution ratios of 0.0, 10.0, and 25.0% were considered, and mechanical and durability tests on the curb specimens were conducted at 28 and 91 days of age. Steam curing was carried out for three days for the production of curbs, which was very effective to strength development at early ages. The reduction in strength at early ages could be compensated through this process, and no significant performance degradation was evaluated in the tests on chloride attack, carbonation, and freezing and thawing. The mortar curb with an ACT of 10.0~25.0% replacement ratio exhibited clear NOx reduction through photocatalytic (TiO2) treatment. This is due to the increase in physical absorption through surface absorption and the photocatalyst-containing TiO2 coating. In this study, the reasonable range of the ACT replacement ratio for NOx reduction was quantitatively evaluated through a comprehensive analysis of each test.