• Nuclear Engineering and Technology
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• v.31 no.5
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• pp.506-511
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• 1999

The pilot system for radioactive liquid laundry waste was developed with treatment capacity, 1ton/hr and set up in the Yong Kwang unit #4. The system is composed of tank module, RO systems and a UV/$H_2O$$_2$photo-oxidation unit. The RO system consists of the BW unit (low-pressure RO for brackish water desalination) and the SW unit (high-pressure RO for seawater desalination). The BW unit possesses 4 RO membranes and it can reduce the feed water volume down to 1/10. This concentrated feed water can be reduced again up to 1/10 in its volume in the SW unit composed of 4 RO membranes. The UV/$H_2O$$_2$ photo-oxidation process unit was used for the detergent degradation. The operation of the pilot system was carried out and verified in its capability through the continuous operation and concentration operation using the actual liquid waste from the power plant. The design criteria and data for industrialization were yielded. The efficiency of the UV/$H_2O$$_2$ photo-oxidation process and the optimum operational procedure were evaluated. The decontamination factors for radioactive cobalt and cesium were measured. This on-site test showed the experimental result in the DF$\geq$300 and volume reduction factor$\geq$100.

• Journal of environmental and Sanitary engineering
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• v.18 no.2
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• pp.52-59
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• 2003

This study was progressed in photocatalysis of VOCs using $UV/TiO_2$ which was a benign process environmentally. The experiments were peformed to know photodegradation characteristics as crystalline structure of $TiO_2$ which had anatase, rutile and P-25 (anatase : rutile = 70 : 30). The main purpose of this study was to identify photocatalytic characteristics as inlet concentration of reactants, $H_2O$, and residence time. The inlet concentration of VOCs was changed 50, 100 and 200 ppmv, and amount of $H_2O$ was changed 0, 500 and $1000{\;}mg/m^3$, respectively. The deep conversion was increased as the inlet concentration decreased, and the amount of $H_2O$ increased. The deep conversion of benzene had the highest value at $1000{\;}mg/m^3${\;}H_2O$ and 50 ppmv of inlet concentration. The reactivity of reactants was decreased in order benzene > toluene > m-xylene. Also, the photocatalytic deep conversion was increased as residence time increased, because the contact time between reactants and catalyst was increased. In this study, intermediates had not found by GC/MSD analysis. Therefore, the reactants were completely converted to $H_2O{\;}and{\;}CO_2$.

• Analytical Science and Technology
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• v.11 no.5
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• pp.332-340
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• 1998

Tridentate Schiff base ligands, $SIPH_2$, $SIPCH_2$, $HNIPH_2$, and $HNIPCH_2$ were prepared by the reactions of salicylaldehyde and 2-hydroxy-1-naphthaldehyde with 2-aminophenol and 2-amino-p-cresol. Ni(II) complexes of those ligands were synthesized. The structures and properties of ligands and their complexes were studied by elemental analysis, $^1H$-NMR, IR, UV-visible spectra, and thermogravimetric analysis. The mole ratio of Schiff base to the metal of complexes was found to be 1:1. Ni(II) complexes were contemplated to be hexa-coordinated octahedral configuration containing three water molecules. The redox process of ligands and complexes in DMSO solution containing 0.1 M TBAP as supporting electrolyte was investigated by cyclic voltammetry and differential pulse voltammetry with glassy carbon electrode. The redox process of the tridentate Schiff base ligands was totally irreversible. The redox process of Ni(II) complexes were quasi-reversible and diffusion-controlled as one electron by one step process Ni(II)/Ni(I). The reduction potentials of the Ni(II) complexes shifted in the positive direction in the order [$Ni(II)(HNIP)(H_2O)_3$]>[$Ni(II)(SIP)(H_2O)_3$]>[$Ni(II)(SIPC)(H_2O)_3$]>[$Ni(II)(HNIPC)(H_2O)_3$] and their dependence on ligands were not so high. Consequently the [$Ni(II)(HNIPC)(H_2O)_3$] complex among the synthesized Ni(II) complexes was found to be most stable in the DMSO solution.

• Analytical Science and Technology
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• v.14 no.1
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• pp.80-87
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• 2001

This research was studied the action of the coupling ozone-hydrogen peroxide on aqueous humic acid. PEROXONE process is enhanced the generation of hydroxyl radicals which is effective for degradation of organic matters. Therefore the changes of $UV_{254}$ and TOC were investigated through the change of concentrations, injection time of $H_2O_2$, initial pH of aqueous humic acid and concentrations of radical savenger as $HCO_3{^-}$ in the PEROXONE processes. And the GC/ECD was used to detect the formaldehyde formed by ozonation of humic acid. From the experimental results, concentrations and injection time of $H_2O_2$ and initial pH in solution in the PEROXONE processes were very important for enhancing the efficiency of degradation in humic acid. The results indicated that removal efficiency of TOC was the highest when concentration of $H_2O_2$ was 5mg/L, injection time of $H_2O_2$ was 5 minutes and initial pH in solution was 10.5. And presence of alkalinity in solution was reduced the efficiency of treatment. The formaldehyde were formed less PEROXONE processes than only ozone. When initial pH in solution were changed from 3.5 to 10.5, the formaldehyde were formed highest concentration at pH 5.

• Environmental Engineering Research
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• v.20 no.2
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• pp.181-189
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• 2015

A composite material was tested to eliminate phenol in aqueous solution combining adsorption on activated carbon and photocatalysis with $TiO_2$ in two different ways. A first implementation involved a sequential process with a loop reactor. The aim was to reuse this material as adsorbent several times with in situ photocatalytic regeneration. This process alternated a step of adsorption in the dark and a step of photocatalytic oxidation under UV irradiation with or without $H_2O_2$. Without $H_2O_2$, the composite material was poorly regenerated due to the accumulation of phenol and intermediates in the solution and on $TiO_2$ particles. In presence of $H_2O_2$, the regeneration of the composite material was clearly enhanced. After five consecutive adsorption runs, the amount of eliminated phenol was twice the maximum adsorption capacity. The phenol degradation could be described by a pseudo first-order kinetic model where constants were much higher with $H_2O_2$ (about tenfold) due to additional ${\bullet}OH$ radicals. The second implementation was in a continuous process as with a fixed bed reactor where adsorption and photocatalysis occurred simultaneously. The results were promising as a steady state was reached indicating stabilized behavior for both adsorption and photocatalysis.

• 한국생물공학회:학술대회논문집
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• 2005.04a
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• pp.272-276
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• 2005

Food wastewater derived from three-stages methane fermentation system showed high concentrations of sCOD, T-N and $NH_{3}-N$. To treat the organic wastewater, the optimal operating conditions for high efficiency $UV/TiO_{2}$ photocotalytic system have been investigated. In the first process, wastewater was pre-treated with $FeCl_{3}. The optimum pH and concentration for coagulation were 4.0 and 2000 mg/L, respectively. Through this process, 52.6% of $COD_{cr}$ was removed. The second process was $UV/TiO_{2}$ photocatalytic reaction. The optimum conditions for the operation of $UV/TiO_{2}$ photocatalytic system developed in this lab have been studied. In this process, CODcr was removed from 2890 to 184 mg/L and T-N was removed from 2496 to 914 for 24 hours, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.377-384
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• 2005

Algae causes not only the eutrophication of lake, but also the deterioration of drinking water process. Especially, algogenic organic matters(AOM) are assumed as disinfection by-products(DBPs) precursors like humic and fulvic acids. In this study, it was investigated the characteristics changes of algogenic organic matter(AOM) by prechlorination and coagulation treatment. Evaluation of enhanced coagulation and applicability of UV oxidation process were also evaluated as the drinking water treatment system for the eutrophicated water source. prechlorination was effective process for algae removal but caused releasing of dissolved organic matter(DOC) into water due to the destruction of algae's cell. In coagulation treatment with Fe(III) coagulant, reaction pH is an important factor for the removal of AOM and triholomathanes(THMs). At pH 5, removal efficiency of DOC and THMs were dramatically improved by 50% and 28%, respectively, in comparison with the conventional coagulation treatment at about pH 7. Photo-Fenton($UV/H_2O_2/Fe^{3+}$) process among the UV oxidations is the most effective system to remove AOM, but its removal efficiency was lower than that of enhanced coagulation treatment at pH 5.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.2
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• pp.219-228
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• 2012

Problems due to the taste and odor in drinking water are common in treatment facilities around the world. Taste and odor are perceived by the public as the primary indicators of the safely and acceptability of drinking water, and are mainly caused by the presence of two semi-volatile compounds-2-methylisoborneol(2-MIB) and geosmin. Conventional treatment processes in water treatment plants, such as coagulation, sedimentation and chlorination have been found to be ineffective for the removal of 2-MIB and geosmin. Pulse UV system is a new UV irradiation system that is a non-mercury lamp-based alternative to currently used continuous wave systems for water disinfection. This study shows pulse UV system to be effective in treatment of these two compounds. Geosmin removal efficiency of UV process alone achieved approximately 70% at 10sec contact time. 2-MIB removal efficiency of UV only process achieved approximately 60% at 10sec contact time. The addition of $H_{2}O_{2}$ 7mg/L increased geosmin and 2-MIB removal efficiency upto approximately 94% and 91%, respectively.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1998.09a
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• pp.103-111
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• 1998

Au fine particle dispersed TiO2 film was prepared on silica glass substrate by sol-gel dip and firing process. The films were fabricated from the system of titanium tetraisoproxie-EtOh-HCl_H2O-hydrogen tetrachloroaurate(III) tetrahydrate. The conditions for the formation of the clear solution and dissolving high concentration of Au compound were examined. And a photoreduction process was adopted to control the size of gold metal particles. Phase evolution of matrix TiO2 and variation of Au particle with UV irradiation were investigated by XRDA, SEM, TEM and UV-visible spectrophotometer. And the effect of CPCl(Cetylpyridinium chloride monohydrate) as a dispersion agent was evaluated.

• Applied Chemistry for Engineering
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• v.9 no.5
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• pp.634-638
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• 1998

Monodisperse, spherical $PMSQ/TiO_2$ composite fine powders were prepared by modified sol-gel process where 300 nm $TiO_2$ fine powders were used as seed particles for hetero-condensation with hydrolyzed MTMS (Methyltrimethoxysilane). The reaction was carried out under $N_2$ atmosphere at ambient temperature using $NH_3$ as a catalyst. Methanol was used as a solvent. Powder was obtained by the filtration of the solution with a glass filter and washing with acetone. The stirring rate, reaction temperature, $[H_2O]/[MTMS]$ and $[MTMS]/[TiO_2]$ ratio were varied to investigate shapes and sizes of particles. Monodisperse particles of $1-2{\mu}m$ diameter were obtained with [MTMS]=0.2 M, $[NH_3]=0.6M$, $[H_2O]/[MTMS]=100$, $[MTMS]/[TiO_2]=10-50$ at ambient temperature with mild stirring condition. These composite particles had a contact angle of almost 180 degree contact angle with water, which proves their excellent hydrophobicity. The study of UV absorption spectra showed that they have UV protecting effect.