• Title/Summary/Keyword: Photo-oxidation

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TiO2-catalytic UV-LED Photo-oxidation of Cyanide Contained in Mine Wastewater (광산폐수 내 시안 제거를 위한 TiO2와 UV-LED를 이용한 광촉매 산화)

  • Kim, Seong Hee;Lee, Sang-Woo;Cho, Hyen Goo;Kim, Young-Ho;Kim, Soon-Oh
    • Journal of the Mineralogical Society of Korea
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    • v.27 no.4
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    • pp.223-233
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    • 2014
  • Cyanidation method has been used to extract high-purity gold and silver in mining industry. Such mining activities have used a large amount of cyanide, and the mine wastewater contained a high level of cyanide has brought about pollution of surrounding aqueous environments. This research was initiated to study $TiO_2$-catalytic UV-LED photo-oxidation to remove cyanide from the mine wastewater. UV lamp has been generally used as a light source in conventional photo-oxidation so far, but it shows numerous drawbacks. For this reason, this study focused on the evaluation of applicability of UV-LED as an alternative light source in cyanide photo-oxidation process. Three types of $TiO_2$ photo-catalyst were compared in terms of performance of photo-oxidation of cyanide, and the results show that Degussa P25 was the most efficient. In addition, four types of UV-LED were tested to compare their efficiencies of cyanide photo-oxidation, and their efficacy was increased in the order of 365 nm lamp-type > 365 nm can-type > 280 nm can-type > 420 nm lamp-type. Not only did this study demonstrate that UV-LED can be used in the photo-oxidation of cyanide as an alternative light source of UV lamp, but also confirmed that the performance of photo-oxidation was significantly influenced by the type of $TiO_2$ catalysts.

The effect of dissolved oxygen and initial complextation of Cu(II) and EDTA on photooxidation of Cu(II)-EDTA by TiO2 (TiO2 광측매를 이용한 Cu(II)-EDTA의 산화에서 용존산소와 Cu(II)와 EDTA 초기 당량의 영향)

  • 정흥호;성기웅;조영현;이영석;최상원
    • Journal of Environmental Science International
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    • v.11 no.1
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    • pp.85-91
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    • 2002
  • The effects of initial concentration of dissolved oxygen content, Cu(II) and EDTA in an aqueous Cu(II)-EDTA solution on $TiO_2$ photo-oxidation of EDTA were investigated using $TiO_2$ (Degussa P-25) and UV irradiation at $20{\circ}C$. In the presence of dissolved oxygen and/or Cu(II) the photo-oxidation rates of EDTA were enhanced. The rates linearly increased in the range of initial Cu(II) concentration below 1.79 mM, while abode this concentration those were kept constant. The trend or the EDTA photo-oxidation rates appeared to be akin to the Langmuir-Hinshelwood equation farm and the k values calculated were 0.05 mM/min for the free-EDTA system, and 0.17 mM/min far the Cu(II)-EDTA system. These meant the aqueous EDTA decomposition was enhanced due to weakening of the intra-molecular bond strength of EDTA by complexation with Cu(II) added. It was concluded the decomposition of aqueous EDTA by $TiO_2$ photo-oxidation was maximum in the presence of dissolved oxygen supplied by air purging and of Cu(II) with its concentration for 1:1 Cu(II)-EDTA complexation ratio.

Development of the Pilot System for Radioactive Laundry Waste Treatment Using UV Photo-Oxidation Process and Reverse Osmosis Membrane

  • Park, Se-Moon;Park, Jong-Kil;Kim, Jong-Bin;Shin, Sang-Woon;Lee, Myung-Chan
    • 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.

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PHOTOCHAIN FREE-RADICAL OXIDATION OF CELLULOSE IN PULP AND PAPER MATERIALS

  • S. I. Kuzina;I. A. Shilova;A. I. Mikahailov
    • Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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    • pp.265-268
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    • 1999
  • Highly effective processes of photo-oxidation of lignocelluose materials affected by light with λ=253.7nm are found. The quantum yield of oxygen absorption ($\phi$02) and evolution of photodegradation gaseous products ($\phi$gas) exceed the unity considerably ($\phi$02=2.5-25). By comparison of $\phi$02 with the quantum yield of initiation, (∼10-3), it is concluded that chain oxidation reactions with a kinetic chain length of 104 - 105 units develop here. An effective evolution of gaseous products ( $\phi$gas 3-50), among them CO2, testifies that there takes place a deep photo-degradation of macromolecules with breaking of C-C bonds in the main polymer chain. The cellulose photo-oxidation under the natural sunlight occurs by the mechanism close to the hydroperoxide one: the length of the photo-oxidation kinetic chain reaches about 40 units.

The Effect of Antioxygenic substances in Pine Needles on the Photooxidation of Linoleic Acid (송옆중의 항산화성 물질이 리놀산의 광산화에 미치는 영향)

  • Paik, Taik-Hong;Lee, Meen-Soo;Yi, Jun-Heung
    • Journal of the Korean Applied Science and Technology
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    • v.4 no.2
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    • pp.25-30
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    • 1987
  • In order to investigate the effect to antioxygenic substances in Pine Needles on the photooxidation of linoleic acid (linoleic acid 100mg/10ml ethanol) added antioxidants and antioxygenic substances in Pine Needles was irradiated by the tungsten lamp attached with red fitter. The Photo oxidation of linoleic acid (LA) was conformed with Lea method and rhodan method. The following results were obtained: 1. Photooxidation of LA was greatly increased the presence of photosensitizer. However the Photo oxidation of LA without photosensitizer was smoothly increased by the irradiation. 2. The Photo oxidation of LA without irradiation occured quite lately whether photosensitizer was present or absent. 3. Photooxidation of LA under the presence of photosensitizer was inhibited by the addition of $dl-{\alpha}-tocopherol$ and the acetone fraction of methanol extract of Pine Needles but inhibited by BHT. Photooxidation of LA increased gradually as the addition of BHT increased but decreased gradually as that of acetone fraction increased.

Advanced Water Treatment of High Turbidity Source by Hybrid Process of Ceramic Ultrafiltration and Photocatalyst: 2. Effect of Photo-oxidation and Adsorption (세라믹 한외여과 및 광촉매 혼성공정에 의한 고탁도 원수의 고도정수처리: 2. 광산화와 흡착의 영향)

  • Cong, Gao-Si;Park, Jin-Yong
    • Membrane Journal
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    • v.21 no.2
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    • pp.201-211
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    • 2011
  • The effects of humic acid (HA), photo-oxidation and adsorption were investigated in hybrid process of ceramic ultrafiltration and photocatalyst for drinking water treatment. UF, photocatalyst, and UV radiation processes were investigated in viewpoints of membrane fouling resistance $(R_f)$, permeate flux (J), and total penneate volume $(V_{\Upsilon})$ at 2 and 4 mg/L of HA respectively. As decreasing HA, $R_f$ decreased dramatically and J increased, and finally $V_{\Upsilon}$ was the highest at 2 mg/L HA. Average treatment efficiencies of turbidity decreased as increasing HA, but treatment efficiency of HA was the highest at 4 mg/L HA. It was because most of HA was removed by membrane and some HA passing through the membrane was adsorbed or photo-oxidized by photocatalyst at low HA, and therefore treated water quality was almost same at 2 and 4 mg/L HA, but feed water quality was higher at 4 mg/L. At effect experiment of photo-oxidation and adsorption, J of UF + $TiO_2$ + UV process was maintained at the highest, and ultimately $(V_{\Upsilon})$ after 180 minutes' operation was the highest. As results of comparing the treatment efficiencies of turbidity and HA, photocatalyst adsorption had more important role than photo-oxidation when HA increased from 2 to 4 mg/L.

Applications of a Hybrid System Coupled with Ultraviolet and Biofiltration for the Treatment of VOCs (휘발성유기화합물 처리를 위한 고도산화법과 고분자 담체 바이오필터 결합시스템의 적용)

  • Shin, Shoung Kyu;Song, Ji Hyeon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.4B
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    • pp.441-447
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    • 2008
  • Volatile organic compounds (VOCs) emitted from various industrial sources commonly consist of biodegradable chemicals and recalcitrant compounds. Therefore, it is not effective to employ a single method to treat such mixtures. In this study, a novel hybrid system coupled with a ultraviolet (UV) photolysis reactor and a biofilter in a series was developed and evaluated using toluene and TCE as model VOCs. When only TCE was applied to the UV reactor, greater than 99% of TCE was degraded and the concentration of soluble byproducts from photo-oxidation reaction increased significantly. However, the toluene and TCE mixture was not effectively degraded by the UV photo-oxidation standalone process. The hybrid system showed high toluene removal efficiencies, and TCE degradation at a low toluene/TCE ratio was improved by UV pretreatment. These findings indicated that the UV photo-oxidation were effective for TCE degradation when the concentration of toluene in the mixture was relatively low. A restively high toluene content in the mixture resulted in an inhibition of TCE degradation. Thus, chemical interactions in both photo-oxidation and biodegradation need to be carefully considered to enhance overall performance of the hybrid system.

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Changes in Natural Antioxidants in Oils Extracted from the Bran and Germ of Keumkang and Dark Northern Spring Wheats During Photo-oxidation (금강밀과 dark northern spring밀의 기울과 배아에서 추출한 기름의 광산화 과정 중 천연산화방지성분의 변화)

  • Choi, Hyun-Ki;Choe, Eun-Ok
    • Korean Journal of Food Science and Technology
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    • v.42 no.1
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    • pp.14-20
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    • 2010
  • Naturally present antioxidants, tocopherols, carotenoids, and phospholipids in the bran and germ oils from Keumkang (K-WBG oil) and Dark Northern Spring wheats (DNS-WBG oil) were determined during storage under 1700 lux light at $5^{\circ}C$ by HPLC. Oil oxidation was monitored by peroxide values (POV) and conjugated dienoic acid content. The results showed that antioxidants were degraded during storage of the WBG oils under light, with higher degradation rates for carotenoids and phospholipids in the K-WBG oil compared to the DNS-WBG oil. Light increased oil oxidation and the rate of oxidation was higher in K-WBG oil than in the DNS-WBG oil. There was a high correlation between POV and residual amounts of antioxidants during photo-oxidation, with phospholipids showing the greatest effects on POV. This study suggests that a higher amount and lower degradation rate of phospholipids in the DNS-WBG oil contributed to its higher photo-oxidative stability compared to the K-WBG oil.

Advanced Water Treatment by Hybrid Process of Multi-channel Ceramic MF and Photocatalyst: Effect of Organic Materials (광촉매 및 다채널 세라믹 정밀여과 혼성공정에 의한 고탁도 원수의 고도정수처리: 유기물의 영향)

  • Amarsanaa, Bolor;Park, Jin-Yong
    • Membrane Journal
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    • v.21 no.4
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    • pp.351-359
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    • 2011
  • For advanced drinking water treatment of high turbidity water, we used the hybrid process that was composed of photocatalyst packing in space of between outside of multi-channel ceramic microfiltration membrane and membrane module inside. Photocatalyst was polypropylene (PP) beads coated $TiO_2$ powder by CVD (chemical vapor deposition) process. Instead of natural organic matters (NOM) and fine inorganic particles in natural water source, standard NOM solution was prepared with humic acid and kaolin. Water-back-flushing of 10 sec was performed per every period of 10 min to minimize membrane fouling. Resistance of membrane fouling ($R_f$) increased and J decreased as concentration of humic acid changed from 2 mg/L to 10 mg/L, and finally the highest total permeate volume ($V_T$) could be obtained at 2 mg/L. Then, treatment efficiency of turbidity and $UV_{254}$ absorbance were above 96.4% and 78.9%, respectively. As results of treatment portions by membrane filtration, photocatalyst adsorption, and photo-oxidation in (MF), (MF + $TiO_2$), (MF + $TiO_2$ + UV) processes, turbidity was treated little by photocatalyst adsorption, and photo-oxidation. However, treatment portions of $UV_{254}$ absorbance by adsorption (MF + $TiO_2$) and photo-oxidation (MF + $TiO_2$ + UV) at humic acid of 4 mg/L and 6 mg/L were above 9.0, 9.5 and 8.1, 10.9%, respectively.