• Journal of Korean Society of Environmental Engineers
• /
• v.29 no.6
• /
• pp.662-669
• /
• 2007

The effect of advanced oxidation processes such as $O_3$, $UV/TiO_2$, $O_3/UV$ and $O_3/UV/TiO_2$ on decolorization and COD removal of Rhodamine B(RhB) wastewater were considered. The results showed that the higher the $O_3$ concentration was, the higher the decolorization observed and the optimum $TiO_2$ dosage was 0.4 g/L in $UV/TiO_2$ and $O_3/UV/TiO_2$ process. $O_3/UV$ process showed the higher initial decolorization rate constant and the shorter termination time for decolorization than those of the $O_3$ process. The decolorization rate constants in various systems followed the order of $O_3/UV/TiO_2>O_3/UV>O_3{\gg}UV/TiO_2$. The decolorization rate of the RhB solution in every processes was more rapid than the mineralization rate identified by COD removal. The latter took longer time for further oxidation. The COD removal rate constants in four systems followed the order of $O_3/UV/TiO_2>O_3/UV>UV/TiO_2{\geqq}O_3$. Among four processes, combined photocatalysis and ozonation$(O_3/UV/TiO_2)$ was the most prospective process for removing color and COD such as dye wastewater.

• Korean Chemical Engineering Research
• /
• v.45 no.6
• /
• pp.648-655
• /
• 2007

UV/H_2O_2$, $O_3$, $O_3/H_2O_2$, $UV/H_2O_2/O_3$ processes were tested for the removal of COD and color from terephthalic acid wastewater. COD removal efficiencies were 10, 48, 56, 63% in the $UV/H_2O_2$, $O_3$, $O_3/H_2O_2$, $UV/H_2O_2/O_3$ process respectively. Color removal efficiency of $UV/H_2O_2$ process was 80% and $O_3$, $O_3/H_2O_2$, $UV/H_2O_2/O_3$ processes were almost more than 99%. Terephthalic acid, isophthalic acid and benzoic acid were completely destructed in terephthalic wastewater within 120 min by $UV/H_2O_2/O_3$ process and shows high COD and color removal efficiencies. The optimum concentration of $H_2O_2$ dosage was found to be 0.5 M, 25 mM and 5 mM for $UV/H_2O_2$, $O_3/H_2O_2$ and $UV/H_2O_2/O_3$ processes respectively, Organic destruction efficiency was enhanced and also reducing the consumption of $H_2O_2$ dosage by combining UV, $H_2O_2$ and $O_3$ process.

• Applied Chemistry for Engineering
• /
• v.18 no.4
• /
• pp.314-319
• /
• 2007

The destruction of synthetic acetic acid wastewater was carried out using UV, $O_3$, $H_2O_2$, $Fe^{2+}$ oxidants in various combinations by the advanced oxidation processes. $UV/H_2O_2$, $UV/H_2O_2/Fe^{2+}$, $O_3$, $O_3/H_2O_2$, $UV/O_3/H_2O_2$, $UV/O_3/H_2O_2/Fe^{2+}$ processes were tested. $UV/H_2O_2/Fe^{2+}$, $O_3/H_2O_2$, $UV/O_3/H_2O_2$, $UV/O_3/H_2O_2/Fe^{2+}$ processes shows the most effective destruction efficiency at low pH (3.5) condition of wastewater, but $UV/H_2O_2$ and $O_3$ processes were observed less than 20%. Destruction efficiency was gradually increased with the reaction time in the $O_3/H_2O_2$ and $UV/O_3/H_2O_2$ processes, in case of the $UV/H_2O_2/Fe^{2+}$ and $UV/O_3/H_2O_2/Fe^{2+}$ processes shows rapid increasing of destruction efficiency within 90 min, then slightly decreasing with time. The destruction efficiencies of $UV/H_2O_2/Fe^{2+}$, $O_3/H_2O_2$, $UV/O_3/H_2O_2$ and $UV/O_3/H_2O_2/Fe^{2+}$ processes were observed 55, 66, 66 and 64%, respectively.

• Journal of Korean Society for Atmospheric Environment
• /
• v.24 no.1
• /
• pp.91-99
• /
• 2008

A multilayer tower-type photoreactor, in which $TiO_2$-coated glass-tubes were installed, was used to measure the vapor-phase BTEX removal efficiencies by ozone oxidation ($O_3$/UV), photocatalytic oxidation ($TiO_2$/UV) and the combination of ozone and photocatalytic oxidation ($O_3/TiO_2$/UV) process, respectively. The experiments were conducted under various relative humidities, temperatures, ozone concentrations, gas flow rates and BTEX concentrations. As a result, the BTEX removal efficiency and the oxidation rate by $O_3/TiO_2$/UV system were highest, compared to $O_3$/UV and $TiO_2$/UV system. The $O_3/TiO_2$/UV system accelerated the low oxidation rate of low-concentration organic compounds and removed organic compounds to a large extent in a fixed volume of reactor in a short time. Therefore, $O_3/TiO_2$/UV system as a superimposed oxidation technology was developed to efficiently and economically treat refractory VOCs. Also, this study demonstrated feasibility of a technology to scale up a photoreactor from lab-scale to pilot-scale, which uses (i) a separated light-source chamber and a light distribution system, (ii) catalyst fixing to glass-tube media, and (iii) unit connection in series and/or parallel. The experimental results from $O_3/TiO_2$/UV system showed that (i) the highest BTEX removal efficiencies were obtained under relative humidity ranging from 50 to 55% and temperature ranging from 40 to $50^{\circ}C$, and (ii) the removal efficiencies linearly increased with ozone dosage and decreased with gas flow rate. When applying Langmuir-Hinshelwood model to $TiO_2$/UV and $O_3/TiO_2$/UV system, reaction rate constant for $O_3/TiO_2$/UV system was larger than that for $TiO_2$/UV system, however, it was found that adsorption constant for $O_3/TiO_2$/UV system was smaller than that for $TiO_2$/UV system due to competitive adsorption between organics and ozone.

• Korean Chemical Engineering Research
• /
• v.45 no.3
• /
• pp.298-303
• /
• 2007

Several combinations of ozone based advanced oxidation processes were tested for the treatment of red water (RW) containing recalcitrant chemical pollutants produced from 2,4,6-trinitrotoluene (TNT) manufacturing process. $O_3$, $UV/O_3$, $UV/O_3/H_2O_2$, $UV/O_3/H_2O_2/Fe^{2+}$ processes were tested for the treatment of RW. The order of organic and color removal efficiency was found to be : $O_3{\leq}UV/O_3$ < $UV/O_3/H_2O_2$ < $UV/O_3/H_2O_2/Fe^{2+}$. The optimum conditions for the removal of organic and color in the $UV/O_3/H_2O_2/Fe^{2+}$ process were 0.053 g/min of ozone flow rate, 10 mM of $H_2O_2$ concentration and 0.1 mM of $FeSO_4$ concentration. Organic and color removal efficiencies were 96 and 100 % respectively in the $UV/O_3/H_2O_2/Fe^{2+}$ process. tert-butyl alcohol (t-buOH) was used as the hydroxyl radical scavenger. Enhancement of hydroxyl radical production was achieved by the combination of ozone with several oxidants such as UV, $H_2O_2$, $Fe^{2+}$.

• Electrical & Electronic Materials
• /
• v.10 no.1
• /
• pp.8-14
• /
• 1997

The UV/O$_{3}$ dry cleaning has been well known in removing organic molecules. The UV/O$_{3}$ dry cleaning method was performed to clean the Si wafer surfaces and contact holes contaminated by organic molecules such as residual PR. During the cleaning process, the Si surfaces were analyzed with X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM) and ellipsometer. When the UV/O$_{3}$ dry cleaning at 200'C was performed for 3 minutes, the residual photoresist was almost removed on Si wafer surfaces, but Si surfaces were oxidized. For UV/O$_{3}$ application of contact hole cleaning, the contact string were formed using the equipment of ISRC (Inter-university Semiconductor Research Center). Before Al deposition, UV/O$_{3}$ (at 200.deg. C) dry cleaning was performed for 3 minutes. After metal annealing, the specific contact resistivity was measured. Because UV/O$_{3}$ dry cleaning removed organic contaminants in contact holes, the specific contact resistivity decreased. Each contact hole size was different, but the specific contact resistivities were all much the same. Thus, it is expected that the UV/O$_{3}$ dry cleaning method will be useful method of removal of the organic contaminants at smaller contact hole cleaning.

• Proceedings of the KIEE Conference
• /
• 2005.11a
• /
• pp.142-144
• /
• 2005

Main purpose of this study is a improved efficiency of Organic light emitting diodes(OLEDs) concerning $UV/O_3$ treatment. We investigated the efficiency of OLEDs by $UV/O_3$ treatment of ITO surface. We measured current density-voltage, luminance-voltage characteristics in different $UV/O_3$ treatment time and observed ITO surface roughness by using AFM(Atomic Force Microscope). The fundamental structure of the OLEDs was $ITO/NPB/Alq_3/LiF/Al$. We performed $UV/O_3$ treatment and found that $UV/O_3$ treatment enhanced the performance of OLEDs. We also found that change of surface roughness according to difference time a $UV/O_3$ treatment

• Journal of Korean Society of Environmental Engineers
• /
• v.28 no.4
• /
• pp.429-437
• /
• 2006

To establish the efficient treatment technology of chemical cleaning wastewater from power plant, several AOPs($UV/H_2O_2,\;UV/TiO_2/H_2O_2$, Photo-Fenton oxidation) were investigated. Treatment efficiencies and the electrical energy requirements based on the EE/O parameter(the electrical energy, required per order of pollutant removal in $1m^3$ wastewater) were evaluated. TOC removal efficiencies of $UV/H_2O_2,\;UV/TiO_2/H_2O_2$, Photo-Fenton oxidation at the optimum conditions were 95.5%, 92.3%, 91.5%, respectively. The electrical energy requirements of $UV/H_2O_2,\;UV/TiO_2/H_2O_2$, Photo-Fenton oxidation were $11.26kWh/m^3,\;3.85kWh/m^3,\;0.799kWh/m^3$, respectively. From these results, it could be concluded that all of the three oxidation processes were effective for the degradation of citric acid. Considering the treatment efficiency and economical aspect, photo-Fenton oxidation was the most efficient treatment process among the three processes tested.

• Applied Chemistry for Engineering
• /
• v.29 no.6
• /
• pp.690-695
• /
• 2018

Advanced oxidation processes (AOPs) composed of O3 and UV were applied to degrade penicillin (PEN). The degradation efficiency was evaluated in terms of changes in the absorbance (ABS) and total organic carbon (TOC). The combination of $O_3/H_2O_2/UV$ and $O_3/UV$ showed the best performance for the reduction of ABS (100% for 9 min) and TOC (70% for 60 min) values, although the mineralization was uncompleted under the experimental condition in this study. The change in biotoxicy was monitored with Escherichia coli susceptibility and Vibrio fischeri biofluorescence. The E. coli susceptibility was eliminated completely for 9 min by $O_3/UV$, and the toxicity to V. fischeri biofluorescence was 57% reduced by $O_3/H_2O_2/UV$. For the ultimate treatment of PEN, it is suggested that an AOP using $O_3/UV$ is followed by biological treatment, utilizing the enhanced biodegradability by the AOP. During 30 min of $O_3/UV$ treatment, the $BOD_5/COD$ ratio as an indication of biodegradability showed about 4-fold increment, compared to that of using a non-treated sample. TOC removal rate for AOP-pretreated PEN wastewater increased 55% compared to that of using the non-pretreated one through an aerobic biological treatment by Pseudomonas putida for artificial wastewater containing 20 mg/L of PEN. In conclusion, $O_3/UV$ process is recommended as a pretreatment step prior to an aerobic biological process to improve the ultimate degradation of penicillin.

• Electrical & Electronic Materials
• /
• v.10 no.2
• /
• pp.166-171
• /
• 1997

The photomachinable glass-ceramics of Ag and CeO$_{2}$ added to Li$_{2}$O-Al$_{2}$O$_{3}$-SiO$_{2}$-K$_{2}$O glass system was investigated as a function of UV irradiation time. The temperature of optimum nucleation and crystal growth temperature were confirmed at 525.deg. C, 630.deg. C respectively using DTA and TMA. The phases of Li$_{2}$O.SiO$_{2}$ habit were lath-like and/or dendrite type and [002] direction of Li$_{2}$O.SiO$_{2}$ / Li$_{2}$O.2SiO$_{2}$ phases were changed according to the UV irradiation time by 400 W, 362 nm UV light source. Under that condition, the optimum UV irradiation time was 5 min.