• Advances in environmental research
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• v.2 no.4
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• pp.261-277
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• 2013

The degradation of alachlor has been investigated using sonolysis (US), photocatalysis (UV) and sonophotocatalysis (US/UV) using three photocatalyst viz. $TiO_2$ (mixture of anatase and rutile), $TiO_2$ (anatase) and ZnO. The effect of photocatalyst loading on the extent of degradation of alachlor has been investigated by varying $TiO_2$ (both types) loading over the range of 0.01 g/L to 0.1 g/L and ZnO loading over the range of 0.05 g/L to 0.3 g/L. The optimum loading of the catalyst was found to be dependent on the type of operation i.e., photocatalysis alone or the combined operation of sonolysis and photocatalysis. All the combined processes gave complete degradation of alachlor with maximum rate of degradation being obtained in the case of sonophotocatalytic process also showing synergistic effect at optimized loading of photocatalyst. About 50% to 60% reduction in TOC has been obtained using the combined process of sonophotocatalysis depending on the operating conditions. The alachlor degradation fitted first order kinetics for all the processes under investigation. It has been observed that the $TiO_2$ (mixtrure of anatase and rutile) is the most active photocatalyst among the three photocatalysts studied in the current work. The effect of addition of radical enhancers and scavengers on sonophotocatalytic degradation of alachlor has been investigated in order to decipher the controlling mechanism. The alachlor degradation products have been identified using LC-MS method.

• Journal of Korean Society on Water Environment
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• v.31 no.4
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• pp.360-366
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• 2015

In this study $TiO_2$ nanotube was grown on Ti by anodic oxidation to be used as a photocatalyst. The growth and formation of $TiO_2$ nanotube was monitored during anodization in ethylene glycol electrolyte by changing voltage and composition of electrolyte. Commercially available titanium plate (purity>99.8%, thickness:1mm) Applied voltage and concentration of $NH_4F$ and $H_2O$ were varied to find the optimum condition. Applied voltage is important to make $TiO_2$ nanotube and the electrolyte containing ethylene glycol, 0.2 wt% $NH_4F$ and 2 vol% $H_2O$ was confirmed to be the optimum conditions for the formation and growth of $TiO_2$ nanotubes.

• Korean Journal of Materials Research
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• v.12 no.10
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• pp.809-813
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• 2002

Commercial nano crystalline $TiO_2$ powders were used to characterize photocatalyst, using thermal spray coating technique. The microstructure of coating layers were examined by SEM, FE-SEM and TEM. Also the cross sectional areas of TiO$_2$ coating layers were observed by SEM. The phases were analyzed by X-ray diffraction methed. Surface roughness and hardness were measured. It was found that phase transformation from anatase to rutile occurred, and the melted splats are all rutile, and unmeted nano particles were anatase. These unmelted anatase phase may enhance te play a role of photocatalyst.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1657-1661
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• 2011

In this study, CdSe-$TiO_2$ photocatalyst were synthesized by a facile solvothermal method and characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and UV-vis diffuse reflectance spectrophotometer. The photocatalytic activity was investigated by degrading methylene blue (MB) in aqueous solution under irradiation of UV light as well as visible light. The absorbance of degraded MB solution was determined by UV-vis spectrophotometer. The results revealed that the CdSe-$TiO_2$ photocatalyst exhibited much higher photocatalytic activity than $TiO_2$ both under irradiation of UV light as well as visible light.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.3
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• pp.559-565
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• 2009

In this paper, we invented a new and unique technique for the sterilization of Escherichia coli(E. coli) in polluted water. We applied a rich ultra-violet(UV) light from pulsed xenon flashlamp and photocatalyst(TiO2) to sterilize E. coli in polluted water. This method based on the use of UV light and photocatalyst is eco-friendly and does not cause secondary pollution. The proposed elliptical reactor is able to concentrate on quartz sleeve coated TiO2 or general quartz sleeve. The primary objective of our research was to determine the important parameters such as pulse repetition rate and input voltage and to know on the sterilizing efficiency of quartz sleeve coated TiO2 and general quartz sleeve. We obtained to achieve 99.999% sterilization in as little as 6 pulses at 800V in case of quartz sleeve coated Ti02, and 10 pulses at 800V in case of general quartz sleeve for 5 minutes. Although transmitted light of quartz sleeve coated TiO2 is deceased, the sterilizing efficiency is increased by 40% than general quartz sleeve. The reason of high sterilizing efficiency is that generated hydroxyl radical(OH) by photocatalyst and is able to concentrate light at a focus by using elliptical reactor.

• Fashion & Textile Research Journal
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• v.5 no.4
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• pp.395-398
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• 2003

In this study, we measured the antibacterial activities, deodorization, UV cut ability, whiteness and SEM, according to the size($5{\mu}m$, $15{\mu}m$) of $TiO_2$, concentration(3%, 5%, 10%) and dipping temperature($50^{\circ}C$, $70^{\circ}C$) with using anatase type of $TiO_2$ photocatalyst. Photocatalyst is the substance which carries out functions, such as decomposition, removal, deodorization, antibacterial, etc. of a contaminant, in a place with light based on an oxidation-reduction reaction. The results of this study were as follow. Antibacterial activities are increased with increasing of the $TiO_2$'s concentration, and $TiO_2$ has high antibacterial activities for Staphylococcus aureus but it has low antibacterial activities for Klebsiella pneumoniae. The deodorization and UV cut ability is very good, therefore be able to get good effects with using only 3% of $TiO_2$. Every effects are increased by using small size of $TiO_2$ and high dipping temperature.

• Journal of environmental and Sanitary engineering
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• v.19 no.2
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• pp.1-6
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• 2004

In Bok-Jeong water treatment plant, chlorination is the only technique used for disinfection of drinking water. This disinfecting treatment leads to the formation of trihalomethanes (THMs). This study was carried out to investigate the possibility of improving removal efficiency of THM precursor in the conventional water treatment processes by $TiO_2$ photocatalytic oxidation. Removal efficiencies of DOC, $UV_{254}$, THMFP were low in the conventional water treatment processes. With application of $TiO_2$ photocatalyst, DOC, $UV_{254}$, THMFP were reduced more effectively. As the $TiO_2$ photocatalytic reaction time increased, the removal efficiencies of DOC, $UV_{254}$, THMFP were increased. The $TiO_2$ photocatalytic removal efficiencies of DOC, $UV_{254}$, THMFP were increased with increasing $TiO_2$ dosage. However, over 0.6g/l of $TiO_2$ dosage, the efficiency reached a plateau.

• Bulletin of the Korean Chemical Society
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• v.35 no.9
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• pp.2660-2664
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• 2014

A simple method of depositing titanium dioxide ($TiO_2$) nanoparticles onto graphene oxide (GO) as a catalytic support was devised for photocatalytic degradation of methylene blue (MB). Thiol groups were utilized as linkers to secure the $TiO_2$ nanoparticles. The resultant GO-supported $TiO_2$ (GO-$TiO_2$) sample was characterized by transmission electron microscopy (TEM), near-edge X-ray absorption fine structure (NEXAFS), and X-ray photoelectron spectroscopy (XPS) measurements, revealing that the anatase $TiO_2$ nanoparticles had effectively anchored to the GO surface. In the photodegradation of MB, GO-$TiO_2$ exhibited remarkably enhanced photocatalytic efficiency compared with thiolated GO and pure $TiO_2$ nanoparticles. Moreover, after five-cycle photodegradation experiment, no obvious deactivation was observed. The overall results showed that thiolated GO provides a good support substrate and, thereby, enhances the photodegradation effectiveness of the composite photocatalyst.

• Korean Chemical Engineering Research
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• v.44 no.4
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• pp.375-381
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• 2006

In this sturdy, spherical activated carbon(SPAC) contained $TiO_2$ was made by ion-exchanged treatment and heat treatment for applying fluidizing bed system. The ion-exchange resin was treated by $TiCl_3$ aqueous solution. The treated resin and raw resin were heat-treated under nitrogen condition to convert into Ti-SPAC. During the heat-treatment, burn-off weight amounts and the element were measured by means of TGA and TGA/MS, individually. The physicochemical properties of Ti-SPAC was characterized by means of XRD, SEM, EDS, BET, EPMA, ESR, intensity and titanium content. The Ti-SPAC had spherical shape with diameter size about $350{\mu}m{\sim}400{\mu}m$ and $617m^2/g$ specific surface area. Structure of $TiO_2$ in Ti-SPAC was anatase and rutile form. Also, $TiO_2$ on SPAC were found that the $TiO_2$ were uniformly distributed through EPMA analysis. Moreover, the Ti-SPAC showed indirect photocatalyst activity estimation through ESR analysis, characteristics of photocatalyst potentially. Over all results, Ti-SPAC was used in fluidizing bed UV/photocatalyst system to remove HA(Humic Acid). That results were HA removal efficiency was about 70％ and Ti-SPAC intensity was preserved during reaction. Ti-SPAC showed practical possibility as photocatalyst in fluidizing bed system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.6
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• pp.1302-1307
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• 2006

This study describes the preparation of high-performance photocatalyst and its environmental applications. We prepared visible-light response nano-particle photocatalyst exhibiting the similar photocatalytic activity with $TiO_2$, dispersed $TiO_2$ on $SiO_2$ with an active rutile type titanium oxide prepared at low temperature. The binder and stable photocatalytic $TiO_2$ sol for photocatalytic system were also prepared. Such products were evaluated by UV/Vis spectrometer, X-ray diffraction analysis, SEM, measurement of photocatalytic activities and surface area, mechanical properties of $TiO_2$-coated surfaces. The results obtained can be applied in efficient photocatalytic systems using POF and metal plate for the purification of air.