In chemistry, the study of sonochemistry is concerned with understanding the effect of sonic waves and wave properties on chemical systems. In the area of chemical kinetics, it has been observed that ultrasound can greatly enhance chemical reactivity in a number of systems by as much as a million-fold. Nano-technology is a super microscopic technology in which structures of 100 nanometers or smaller can be investigated. This technology has been used to develop TiO2 materials and TiO2 devices of that size. Thus far, electrochemistry methods and photochemistry methods have generally been used to create TiO2 nano-size particles. However, these methods are complicated and create pollutants as a by-product. In the present study, nano-scale silver particles (5 nm) were prepared in a sonochemistry method. Sonochemistry deals with mechanical energy that is provided by the collapse of cavitation bubbles that form in solutions during exposure to ultrasound. TiO2 powders 25 nm in size doped with Ag were formed using an ultrasonic sound technique. The experimental results showed the high possibility of removing pollution through the action of a photocatalyst. This powder synthesis technique can be considered as an environmentally friendly powder-forming processing owing to its energy saving characteristics.

Treatment characteristics of benzene were investigated by using a fixed bed reactor system applying a hybrid method over composites of photocatalyst and adsorbent. Various composites were made by mixing photocatalyst with adsorbent, such as activated carbon, activated carbon fiber, and sludge. Performance tests were conducted with benzene concentrations of 1,000～3,000 ppm, Benzene flow rates of 50～100cc/min, and packing weights of 14～24g for the various composite samples. The property of benzene treatment was analyzed concerning BET, SEM, pH, and the conversion efficiency. It was concluded by experimental results that the benzene conversion efficiency of a hybrid method was much higher than that of a photocatalyst only method showing a conversion efficiency range between 13% and 65%. It was also found that the comprehensive feasibility study of the hybrid method would be needed with consideration of various factors including additional expenses.

the less-reported gaseous studies have primarily dealt with chemical process stream concentrations than indoor air quality (IAQ) concentration levels. Accordingly, the current study was conducted to establish the feasibility of applying visible-light-induced TiO₂ doped with sulfur (S) element to cleanse toluene and ehtyl benzene at IAQ levels. The S-doped TiO₂ was prepared by applying two popular processes and two well-known methods. For both target compounds, the two coating methods exhibited different photocatalytic oxidation (PCO) efficiency. Similarly, the two S-doping processes showed different PCO efficiency. These results indicate that the coating method and doping process are important parameters which can influence PCO efficiency. Meanwhile, it was found that the PCO efficiency of ethyl benzene was higher than that of toluene. In addition, the degradation efficiency of the target compounds increased as the relative humidity (RH) decreased. The PCO efficiency varied from 44% to 74% for toluene and from 68% to 95%, as the RH decreased. Consequently, it is suggested that with appropriate RH conditions, the visible-light-assisted photocatalytic systems can also become an important tool for improving IAQ.

Nano-sized TiO2-60 wt% SrO composite powders were synthesized by a sol-gel method using titanium isopropoxide and Sr(OH)2 · 8H2O as precursors. 3, -5, -7 wt%Ag spot-coated TiO2-60 wt% SrO composite powders were synthesized by a Ag electroless deposition method using TiO2-60 wt% SrO composite powders calcined at 1050˚C, which mainly exhibited the SrTiO3phase. However, a small number of rutile TiO2, Sr2TiO4 and SrO2 phases were also detected. In the Ag spot-coated powders synthesized by electroless deposition, nano-sized particles about 5-25 nm in diameter adhered to the TiO2-60 wt% SrO composite powders. The photocatalytic activity of Ag spot-coated TiO2-SrO and TiO2-SrO composite powders for degradation of phenol showed that all of TiO2-SrO composite powders were highly active under UV light irradiation. 7 wt%Ag spot-coated TiO2-60wt.%SrO composite powders had a relatively higher photocatalytic activity than did TiO2-SrO composite powders under visible light.

A ZrO2 coating solution containing ZrO2 photo-catalysis, which is transparent in visible light, was prepared by the hydrolysis of alkoxide, and thin films on the SiO2 glass substrate were formed in a dipcoating method. These thin films were heat-treated at temperatures ranging from 250˚C-800˚C and their characteristics were subjected to thermal analysis, XRD, spectrometry, SEM, EDS, contact angle measurement, and AFM. Tetragonal ZrO2 phase was found in the thin film heat treated at 450˚C, and anatase TiO2 phase was detected in the thin film heat-treated at 600˚C and above. The thickness of the films was approximately 300 nm, and the roughness was 0.66 nm. Thus, the film properties are excellent. The films are super hydrophilic with a contact angle of 4.0˚; moreover, they have self-cleaning effect due to the photo catalytic property of anatase TiO2.

This paper presents applicability of photocatalytic decomposition of methyl mercaptan using TiO2. A quartz reactor was used in order to elucidate reaction pathway in photocatalytic decomposition of methyl mercaptan. Experimental results showed that more than 99.9% of methyl mercaptan was decomposed within 30 minutes. It was found that the photocatalytic decomposition of methyl mercaptan followed pseudo first order and its reaction coefficient was 0.05min-1 During 30 minutes in the photocatalytic reaction, the concentration of methyl mercaptan, dimethyl disulfide, SO2, H2SO4, COS, H2S were determined. These results showed that 64% of methyl mercaptan were compensated for the increase in sulfur after 30 minutes through the mineralization. The proposed main photocatalytic decomposition pathway of methyl mercaptan was methyl mercaptan→dimethyl disulfide→SO2→H2SO4.

광촉매 반응이 자연유기물에 의한 나노여과막의 오염에 미치는 영향을 살펴보았다. 광촉매 분해공정은 자연유기물의 분해와 변형에 효율적이었으며 이산화티타늄과 고정화 비드를 광촉매로 사용하였다. 광촉매적 특성을 비교하기 위하여 칼슘 이온 존재 시의 휴민산의 광분해를 모델 반응으로 설정하였다. 광분해 전에는 치밀한 막오염층이 형성되어 막오염을 가속화시킨 반면, 광분해 후에는 막오염이 크게 감소하였다.

It prepared the TiO2 powder which has photo-catalytic activity in the visible-light by the wet process with titanium oxysulfate. The titanium dioxide(TiO2) by the wet process creates a new absorption band in the visible light region, and is expected to create photocatalytic activity in this region. Anatase TiO2 powder which has photocatalytic activity in the visible light region, is treated using microwave and radio-frequency(RF) plasma. But, the TiO2 powder for the visible light region, which also can be easily produced by wet process. The wet process TiO2 absorbed visible light between 400nm and 600nm, and showed a high activity in this region, as measured by the oxidation removal of aceton from the gas phase. The AH-380 sample appears the yellow color to be strong, the catalytic activity in the visible ray was excellent in comparison with the plasma-treated TiO2. The AH-380 TiO2 powder, which can be easily produced on a large scale, is expected to have higher efficiency in utilizing solar energy than the plasma-treated TiO2 powder.

Activated carbon fiber (ACF) filters are widely used to remove volatile organic compounds (VOCs) in air cleaning devices. The performance of ACF filters could be enhanced combining adsorption process with photodegradation process. In this study, to investigate this enhancement effect, a duct-type reactor was made and TiO2 was i㎜obilized on a co㎜ercialized ACF filter. Benzene, toluene, and m-xylene (BTX) were chosen as target compounds. Removal experiments for BTX were done under different air velocity and upstream concentration conditions. The range of inlet concentration was 200～1,400 ppb and the air velocities were 0.4, 0.7 and 1.0 m/s. Adsorption by an ACF filter alone showed high removal efficiency of BTX, depending on the BTX species, the upstream concentration, and the air velocity. The combination of TiO2 and ACF filter significantly increased removal of benzene which was less removed than other pollutants by an ACF filter alone. It was found that the combination effect was small in removal test of toluene and m-xylene. Removal efficiency in the tested experimental conditions was decreased in order of toluene > m-xylene > benzene.

Transition metal doped nanostructured powders were synthesized by mechanical alloying(MA) to shift the adsorption threshold into the visible light region. The synthesized powders were characterized by XRD, SEM, TEM and BET for structural analysis, UV-Vis and photoluminescence spectrum for the optical study. Also, photocatalytic abilities were evaluated by decomposition of 4-chlorophenol(4CP) under ultraviolet and visible light irradiations. Optical studies showed that the absorption wavelength of transition metal ions doped powders moved to visible light range, which was believed to be induced by the energy level change due to the doping. Among the prepared powders, doped powders, showed excellent photooxidative ability in 4CP decomposition

Titanium dioxide was prepared by Polymer Complex Solution Method(PCSM) according to the mole ratio of Titanium (IV) isopropoxide(TTIP)/solvent and polymer(Poly Ethylene Glycol). Polymer electrolytes were usually made by dispersing preproduced ceramic nanoparticles in a polymer matrix. Using this method, pure and nano-sized powder was synthesized through a simple procedure and polymer entrapment route. At the optimum amount of the polymer, the titanium ions are dispersed in solution and a homogeneous polymeric network is formed. The maximum intensity of anatase phase of was achieved by calcining at for 2h. The synthesized powders were nano-sized and the average size was about 50nm. Anatase/Rutile ratio of the synthesized was 70%/30%