• Journal of the Korean GEO-environmental Society
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• v.7 no.3
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• pp.21-29
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• 2006

The treatment performance of ozonation and three types of advanced oxidation processes (AOPs) such as $O_3/H_2O_2$, $O_3/UV$, $O_3/H_2O_2/UV$ was experimentally investigated for the treatment of refractory synthetic dye wastewater. The removal efficiency of $COD_{cr}$, color and biodegradability ($BOD_5/COD_{cr}$) were relatively evaluated in each treatment unit with simulated dye wastewater. Optimal operational conditions of pH, temperature, dosage and circulation flow rate were also investigated. All suggested processes revealed an effectiveness for the removal of color within a short operational time, moreover, $O_3/H_2O_2/UV$ process showed the highest $COD_{cr}$ removal and biodegradability enhancement among proposed oxidation process.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.7
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• pp.1307-1318
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• 2000

The purpose of this study is to investigate the degradation characteristics of oxalic acid and citric acid by $UV/H_2O_2$ oxidation. For this purpose, the effects of pH, $H_2O_2$ dosage and the concentration of each compounds on the degradation of oxalic acid and citric acid by $UV/H_2O_2$ were investigated. Oxalic acid was effectively degraded at the wavelength of 254 nm, while the degradation efficiency of citric acid was very low at the same wavelength. It was also found that both organic substances were not degraded by the injection of $H_2O_2$ only. The optimum pH of degradation of oxalic acid and citric acid was 4 and 4 to 6, respectively. In the case of $UV/H_2O_2$ oxidation, the degradation efficiency was increased by increasing $H_2O_2$ dosage. The degradation efficiency decreased when the dose of $H_2O_2$ exceeds 200 mg/L. From these results, it can be concluded that the optimum reaction conditions for the degradation of oxalic acid and citric acid by $UV/H_2O_2$ oxidation were pH 4 and 200mg/L of $H_2O_2$.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.10
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• pp.1039-1046
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• 2008

The combining process of UV irradiation and H$_2$O$_2$ was used to investigate characteristics of cefaclor decomposition in the aquatic environment. The separate mixing tank was used to minimize the decreasing effective of contact area caused by sampling. Four baffles were installed inside the UV reactor for the complete mixing of the sample and outside of the reactor was wrapped with aluminum foil to protect the emission of photon energy. Production of OH radical was measured using pCBA(p-Chlorobenzoic acid) indirectly and rate constants were withdrawn pseudo-frist order reaction. Optimum condition for the maximum production of OH radical was found to be pH 3, hydrogen peroxide of 5 mmol/L and recirculation rate of 400 mL/min. Pseudo-frist order reaction rate constant was 0.1051 min$^{-1}$. In the optimum condition, cefaclor was completely decomposed within 40 min and rate constant was 0.093 min$^{-1}$. Decomposition by OH radical producted intermediate anions such as chloride, nitrate, sulfite and acetic acid and phenylglycine. After 6 hr most cefaclor was decomposed by UV/H$_2$O$_2$ process and converted to CO$_2$ and H$_2$O, resulting of operation in the decrease of TOC and acetic acid and the disappearance of phenylglycine.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.645-654
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• 1994

Photocatalytic oxidation conditions of reactant recirculation flow rate 275 mL/min, aeration rate 2 LPM and $UV+TiO_2+H_2O_2$(500 mg/L) proved to be appropriate for water including organic materials treatment. With increasing turbidity and suspended solids concentration, at turbidity 10 NTU-suspended solids concentration 29 mg/L the phenol degradation efficiency increased, which in turn decreased at turbidity 50 NTU-suspended solids concentration 170 mg/L, however no significant differences were observed, demonstrating similar results with those obtained at zero turbidity and suspended solids concentration. The degradation efficiency of phenol decreased with increasing influent phenol concentrations. The $UV+TiO_2+H_2O_2$ photocatalytic advanced oxidation process conducted is considered to be possibly applied to the drinking water treatment, and the post-treatment process of biological wastewater treatment.

• Journal of Korean Society on Water Environment
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• v.23 no.3
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• pp.319-323
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• 2007

The Advanced Oxidation Process (AOP) is being increasingly used to oxidize complex organic constituents in treated effluents from domestic wastewater treatment plants. Generally, ${NO_3}^--N$ concentrations ranges between 5 and 8 mg/L for biologically well-treated effluents. However, nitrate ions, ${NO_3}^-$, affects on oxidation as not only a well-known strong absorber of UV light below 250 nm of wavelength but also as an OH radical scavenger. The objective of this study was to evaluate the AOP systems for degradation of 2,4-DCP, and to delineate the effect of nitrate ions on UV oxidation of 2,4-DCP by conducting a bench-scale operation at various reaction times and initial concentrations of $H_2O_2$. The experimental results indicated that 2,4-DCP could be completely oxidized by $UV/H_2O_2$ process with an initial $H_2O_2$ concentration of 20 mg/L at a retention time of 1.0 min or longer. Nitrate ions did not show any adverse effect on 2,4-DCP oxidation at this high $H_2O_2$ concentration, and the practical initial $H_2O_2$ concentration and reaction time for the 80% oxidation turned out to be 5 mg/L and 1.0 min, respectively.

• Journal of Korean Society on Water Environment
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• v.36 no.4
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• pp.314-321
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• 2020

This study evaluated the applicability of UV-AOP process using medium-pressure UV lamp and H₂O₂ to remove TOC and emerging micropollutants in the effluent from a sewage treatment plant. The UV lamp with higher output(1.6~8.0 kW) showed slightly higher amount of power in removing TOC of 1 mg/L(0.09 kWh/mg/L~0.11 kWh/mg/L), however it was found that there was no significant difference for each cases. In addition, under the condition that the H₂O₂ concentration is sufficient, as the power consumption of the UV lamp increases, the unit TOC removal concentration per unit H₂O₂ decomposition concentration also increases, resulting in effective removal of TOC. The removal rate of 7 new trace contaminants, such as antibiotics by the UV-AOP tested, was at least 89.4%, and the ability to remove the emerging micro pollutants in the process was very effective. But, it was judged that it could not be excluded that the probablity of transforming to oxidated by-product in the case of a low TOC removal efficiency. Depending on the operating conditions of the UV and H₂O₂ processes, a higher BOD concentration is found in the treated water than in the influent, and it is necessary to review the UV power and proper injection conditions of H₂O₂ to maintain the BOD concentration increase below a certain level.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.3
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• pp.377-384
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• 2004

In the present study, a feasibility of an advanced oxidation process using UV/Hydrogen peroxide($H_2O_2$) system equipped with a medium pressure lamp for secondary effluent reclamation was investigated. Initial concentration of $H_2O_2$ and pH were changed to determine the optimum operation condition for the system. The removal efficiency of color was than 80% with 14.3mg/L of initial $H_2O_2$ and 5 minute of contact time in the UV/$H_2O_2$ system. The color removal was analyzed using first-order reaction equation. The dependence of rate constant (k) on initial $H_2O_2$ represented the rational relationship with maximum value. Residual $H_2O_2$ caused increase of effluent COD, since analyzing agent, dichromate, reacted with $H_2O_2$ in the sample. Therefore, excess initial concentration of $H_2O_2$ would significantly affect effluent COD measurement. At pH variation experiment, both residual $H_2O_2$ and color showed peak in the neutral pH range with the same pattern. Effect of $H_2O_2$ dose also enhanced color removal but raised residual $H_2O_2$ problem in the continuous operation UV system. In conclusion, these results indicated that medium pressure UV/$H_2O_2$ system could be used to control color in the secondary effluent for reclamation and reuse.

• Applied Chemistry for Engineering
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• v.26 no.3
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• pp.270-274
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• 2015

We develop advanced oxidation processes for the treatment of spent electroless nickel plating solution. Apart form recovering nickel by leaching and enrichment, more emphasis is placed on rendering the waste water recyclable via oxidizing phosphite and hypophosphite into phosphate which can then be precipitated easily. $UV/H_2O_2$ process is employed and the conversion efficiency of COD and $PO_4-P$, and $H_2O_2$ consumption are analyzed. Furthermore, the $UV/H_2O_2/O_3$ process in conjunction with $O_3$ generator enables us to not only save the treatment time by 6 hours but also reduce $H_2O_2$ consumption by 30%.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.6
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• pp.779-786
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• 2012

The degradation of 2-chlorophenol(2-CP) by various AOPs(Advanced Oxidation Processes) including the photo-Fenton process has been examined. In sole $Fe^{2+}$, UV or $H_2O_2$ process without combination, low removal efficiencies have been achieved. But the photo-Fenton process showed higher removal efficiency for degradation of 2-chlorophenol than those of other AOPs including the Fenton process and the UV processes. In the photo-Fenton process, the optimal experimental conditions of 2-chlorophenol degradation were obtained at pH 3 and the $Fe^{2+}/H_2O_2$molar ratio of 1. Also the 2-chlorophenol removal efficiency increased with decreasing of the initial 2-chlorophenol concentration. 3-chlorocatechol and chlorohydroquinone were identified as photo-Fenton reaction intermediates, and a degradation pathway of 2-chlorophenol in the aqueous phase during the photo-Fenton reaction was proposed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.1
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• pp.23-28
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• 1999

Au fine particles dispersed $TiO_{2}$ film was prepared on silica glass substrate by sol-gel dipping and firing process. The $TiO_{2}$ films were fabricated from the system of titanium tetraisopropoxide-EtOH-HCl-$H_{2}O$-hydrogen tetrachloroaurat (III) tetrahydrate. The conditions for the formation of clear solution and dissolving high concentration of Au compound were examined. Photoreduction process was adopted to control the size of gold metal particles. Phase evolution of matrix $TiO_{2}$ and variation of Au particle with UV irradiation were investigated by XRD, SEM, TEM and UV-visible spectrophotometer. The effect of CPCl (Cetylpyridinium chloride monohydrate) as a dispersion agent was evaluated.