• Journal of Korean Society of Water and Wastewater
• /
• v.30 no.5
• /
• pp.501-509
• /
• 2016

In this study, a flat-type photocatalytic reactor is applied under solar irradiation for simultaneous treatment of target pollutants: reduction of Cr(VI) to Cr(III) and oxidation of EDCs (BPA, EE2, E2). An immobilized type of photocatalyst was fabricated to have self-grown nanotubes on its surface in order to overcome limitations of powdery photocatalyst. Moreover, Ti mesh form was chosen as substrate and modified to have both larger surface area and photocatalyst content. Ti mesh was anodized at 50V and $25^{\circ}C$ for 30min in the mixed electrolytes ($NH_4F-H_2O-C_2H_6O_2$) and annealed at $450^{\circ}C$ for 2 hours in ambient oxygen to have anatase structure. Surface characterization was done with SEM and XRD methodologies. Fabricated NTT was applied to water treatment, and coexisting Cr(VI) and organics (EDCs) enhanced each other's reactions by scavenging holes and electrons and thus impeding recombination. Also, several experiments were conducted outdoor under direct sunlight and it was observed that both solar-tracking and applying modified photocatalyst were proven to enhance reaction efficiency.

• Journal of Korean Society for Atmospheric Environment
• /
• v.18 no.3
• /
• pp.223-230
• /
• 2002

Titania photocatalytic oxidation reactors were studied to investigate degradation efficiencies of hydrocarbons. In general, it is well known phenomena that thin layered titania oxidizes most of hydrocarbons to carbon dioxide and water under UV light. In this study, degradation efficiencies were measured due to changes in reactor structures, UV sources, the number of titania coatings, and various hydrocarbon chemicals. It was proven that gas degradation efficiencies are related to such factors as UV transmittance of coating substance, collision area of surface, and gas flow rate. For packing type annular reactor, about 98% degradation efficiency was achieved for achieved for propylene of 500 ppm level at a flow rate of 100 ml/min. Several gases were also tested for double-coated titania thin film under the condition of continuous flow of 100 ml/min and 365 nm UV source. It was shown that degradation efficiencies were decreasing in the order: $C_3$ $H_{6}$, n-C$_4$ $H_{10}$, $C_2$ $H_4$, $C_2$ $H_2$, $C_{6}$ $H_{6}$ and $C_2$ $H_{6}$./. 6/./.

• Advances in environmental research
• /
• v.1 no.4
• /
• pp.289-304
• /
• 2012

Tris (2-methyl-1-aziridinyl) phosphine oxide (MAPO) is extremely poisonous and persistent in aqueous media. An efficient UV/nano$TiO_2$ process was employed for its mineralization in a high duty falling film photo-reactor based on an experimental design scheme that considers interactions between the main variables. The influencing variables and their range were determined with preliminary studies. The results show substrate mineralization to some extent under mild conditions of: T = $30^{\circ}C$, pH = 8.5, $[MAPO]_0=60\;mg\;L^{-1}$ and $[TiO_2]=110\;mg\;L^{-1}$. The relative importance of the influencing parameters were initial pH > temperature > $[MAPO]_0$ > [$TiO_2$]; while the interdependence of all the parameters was significant. Accordingly, a reduced quadratic expression was developed. Meanwhile, mineralization kinetic studies, based on chemical oxygen demand, revealed a power law model with order of 2.6 during process time until 150 min.

• Journal of Industrial Technology
• /
• v.24 no.B
• /
• pp.133-138
• /
• 2004

The photodegradation of phenol and toluene with the $TiO_2$-coated polyethylene (PE) particles were investigated in the slurry type photocatalytic reactor, changing the $TiO_2$ particle sizes, initial phenol and toluene concentrations, and the oxygen flow rate. The nano-sized $TiO_2$ photocatalyst particles were prepared by the diffusion flame reactor and they were coated onto PE particles by using the hybridization system for the efficient recollection of $TiO_2$-coated particles after photodegradation experiments. The degradation efficiencies of phenol and toluene with the $TiO_2$-coated PE particles were more than 90% after photodegradation of 80 minutes for most cases. The efficiencies of photodegradation with the $TiO_2$-coated PE particles were found to be lower than those by the pure $TiO_2$ particles by 50%, because of the decrease in specific surface area of $TiO_2$ particles in PE particles.

• Journal of Environmental Health Sciences
• /
• v.31 no.5 s.86
• /
• pp.415-422
• /
• 2005

The photocatalytic decolorization of Reactive Red 2B(RR2B) was studied using immobilized photocatalyst/UV System. Two pairs of 20 W UV-B and UV-C lamps were employed as the light source. Immobilization of $TiO_2$ was carried out using sponge (as the photocatalyst body) and silicone sealant(as the binder). The effects of parameters such as the thickness, pore size of sponge photocatalyst and attached material on the reactor bottom were investigated. The results showed that the optimum thickness of sponge photocatalyst was 1 cm. Decolorization of reactor which had the bottom coated $TiO_2$ was higher than that of reactor attached aluminum plate. Decolorization of photocatalyst with large pore size(mean pore size, 3.8 mm) was higher than that of the small(mean pore size, 1.75 mm). Initial decolorization of RR2B could be descrived using the Langmuir-Hinshelwood(L-H) model and gave constant values of $0.55mg/l{\cdot}min(k)\;and\;2.65{\times}10^{-2}l/mg(K)$, respectively.

• Korean Chemical Engineering Research
• /
• v.57 no.2
• /
• pp.259-266
• /
• 2019

Tuning of electro-optical properties of nano-structured $SnO_2:Ga$ powders in a micro drop fluidized reactor (MDFR) was highly effective to enhance the activities of powders to be used as sensor materials. The tuning was conducted continuously in a facile one-step process during the formation of powders. The microscopic hydrodynamic forces affected the band gap structure and charge transfer of $SnO_2:Ga$ powders through the oxygen and interfacial tin vacancies by providing plausible pyro-hydraulic conditions, which resulted in the decrease in the electrical resistance of the materials. The analyses of room-temperature photoluminescence (PL) spectra and FT-IR exhibited that the tuning could improve the surface activities of $SnO_2:Ga$ powders by adjusting the excitation as well as separation of electrons and holes, thus maximizing the oxygen vacancies at the surface of the powders. The scheme of photocatalytic mechanism of $SnO_2:Ga$ powders was also discussed.

• Journal of Korean Society of Water and Wastewater
• /
• v.12 no.3
• /
• pp.55-64
• /
• 1998

The degradation efficiency of chlorophenolic compounds in $TiO_2/H_2O_2$ combined system was compared with that of in $TiO_2$ sole system. As a result, the addition of hydrogen peroxide in photocatalytic oxidation reaction greatly enhanced the degradation efficiency of chlorophenolic compounds due to the availability of the hydroxyl radical formed on the $TiO_2$ surface. The hydrogen peroxide under UV illumination produces hydroxyl radicals that appear to be another source of hydroxyl radical formation. These results indicated the $TiO_2/H_2O_2$ combined system shows higher degradation efficiency than the $TiO_2$ sole system. Compared to another oxidation reaction, hydrogen peroxide assisted photocatalytic oxidation is more promising in practical aspect.

• Journal of Urban Science
• /
• v.8 no.2
• /
• pp.29-34
• /
• 2019

Benzene pollution is becoming increasingly serious, and the treatment technology of benzene has attracted much attention. In this paper, a self-made photocatalytic reactor was used to explore the removal rate of benzene under the ultraviolet light with the wavelength of 253.7nm. The results showed that the degradation rate of benzene decreased from 64.29% to 16.26% when the concentration increased from 43mg/㎥ to 256mg/㎥ under the condition of 28W UV light intensity and 50s residence time. Under the condition of 28W UV light intensity and 103mg/㎥ concentration, the residence time increased from 16.5s to 50s, and the benzene removal rate increased from 13.23% to 42.72%.Under the condition of benzene concentration 103mg/㎥ and residence time of 50s, the removal rate of benzene increased from 29.34% to 52.58% in the process of UV light intensity rising from 28W to 48W.It is concluded that decreasing the concentration and increasing the residence time of gas were beneficial to the removal of benzene and increasing the light intensity can improve the removal rate of benzene.

• Journal of the Korean Applied Science and Technology
• /
• v.34 no.2
• /
• pp.349-356
• /
• 2017

OH radical generation is one of the common method to evaluate photocatalytic activity. In many of previous studies, only the UV(Ultraviolet) light was applied to test photocatalytic ability of $TiO_2$ nanotubes by studying probe compound(4-Chlorobenzoic acid) concentration change in solution. Also, $TiO_2$ nanotubes were found to show some electrochemical characteristics when the flow of electric current was applied. In this study, the flow of electric current and UV light were applied at the same time to determine whether electrochemical characteristics of $TiO_2$ nanotube plate can give synergetic effect on the photocatalytic activity. $TiO_2$ nanotube was grown on Ti by anodic oxidation to create $TiO_2$ nanotube plate which can be used as a photocatalyst and a electrode that can undergo AOP(Advanced Oxidation Process) for water treatment. Probe compound solution was prepared using 4-chlorobenzoic acid and $H_2O$ as a solvent. NaCl was added to give conductivity to work as electrolyte. As a result, enough level of electric current flow was found to give synergetic photocatalytic effect which can be used for efficient AOP water treatment method.

• Korean Chemical Engineering Research
• /
• v.50 no.6
• /
• pp.945-951
• /
• 2012

The effect of photocatalyst-carrying media porosity on the photocatalytic removal efficiency of malodor and VOC of waste air was evaluated when the photocatalytic removal efficiency of porous silica-based media was compared with that of glass bead as control. The amount of photocatalyst coated on the surface of porous silica-based media was observed to be $1,716.3{\mu}g/cm^2$, which was 250% as much as that of nonporous glass bead (control) of $670{\mu}g/cm^2$. The removal efficiencies of hydrogen sulfide and toluene in case of porous silica-based media were observed to be 22% and 82%, respectively, while the removal efficiencies of hydrogen sulfide and toluene in case of nonporous glass bead media were observed to be 19% and 53%, respectively. Therefore, the removal efficiencies of hydrogen sulfide and toluene increased by 16% and 55%, respectively, when the removal efficiencies of porous silica-based media were compared with those of nonporous glass bead media. Thus the increment ratio of the removal efficiency of toluene was observed to be 3.4 times higher than that of hydrogen sulfide.