• Journal of Food Hygiene and Safety
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• v.33 no.6
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• pp.495-499
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• 2018

The reduction effect of UV-C irradiation and mild heat treatment was examined against Escherichia coli O157:H7 and Salmonella Typhimurium on black pepper powder. E. coli O157:H7 (ATCC 35150) and S. Typhimurium (ATCC 19585) were inoculated onto black pepper powder at approximately $10^7$ and $10^6CFU/g$, respectively. E. coli O157:H7 and S. Typhimurium were treated with UV-C and mild heat at $60^{\circ}C$. A UV-C intensity ($2.32W/cm^2$ ) was used for 10 min to 70 min at $60^{\circ}C$. After UV-C and heat treatment at $60^{\circ}C$, microbial analysis and color change of black pepper powder was conducted. E. coli O157:H7 and S. Typhimurium were reduced by a level of 1.89 and 2.24 log CFU/g, respectively, when treated with UV-C alone for 70 min. And E. coli O157:H7 and S. Typhimurium were reduced by 2.22 and 5.10 log CFU/g, respectively, when treated with mild heat treatment at $60^{\circ}C$ alone for 70 min. But when combined with UV-C and mild heat, it showed higher levels of reduction by 2.46 and 5.70 log CFU/g. S. Typhimurium was more easily reduced than E. coli O157:H7. Color values were not significantly (p > 0.05) different in all treated samples. Therefore, these results suggest that the combined treatment with UV-C and mild heat was effective to inactivate the food pathogens in black pepper powder and can be used as a food industrial microbial intervention method.

• Journal of environmental and Sanitary engineering
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• v.15 no.4
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• pp.27-27
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• 2000

In order to treat the dyeing wastewater, the UV/TiO₂/H₂O₂ system was investigated, and proper pretreatment methods were examined to reduce the load on the system considering economical and technical efficiency. The results of this study were as follows: 1.UV/TiO₂/H₂O₂ system with pretreatment process was adopted, the result of Chemical coagulation and pH control units was pH 11→ coagulation → pH 4 and the optimum dosage of FeCl₃ was 600㎎/ℓ 2. Proper dosage of TiO₂in the UV/TiO₂/H₂O₂ system with pretreatment process was 2g/ℓ and H₂O₂ was 1000㎎/ℓ, UV contact time was 20min to get below 200㎎/ℓ of $COD_{Cr}$

• Transactions on Electrical and Electronic Materials
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• v.17 no.4
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• pp.204-207
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• 2016

Experimental study of UV-irradiated O₂/H₂ gas phase cleaning for PMMA (Polymethylmethacrylate) removal is carried out in a load-locked reactor equipped with a UV lamp and PBN heater. UV enhanced O₂/H₂ gas phase cleaning removes polymethylmethacrylate (PMMA) better at lower process pressure with higher content of H₂. O₂ gas compete for UV (184.9 nm) absorption with PMMA producing O₃, O(¹D) and lower dissociation of PMMA. In our experimental conditions, etching reaction of PMMA at the substrate temperature between 75℃ and 125℃ had activation energy of about 5.86 kcal/mol indicating etching was controlled by surface reaction. Above the 180℃, PMMA removal was governed by a supply of reaction gas rather than by substrate temperature.

• Journal of the Korean GEO-environmental Society
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• v.23 no.10
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• pp.5-12
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• 2022

In this study, we investigated the UV/H₂O₂ process to treat organic compound-spilled water. In consideration of usage and properties, benzene, toluene, phenol, and methyl ethyl ketone were selected as representative organic compounds. The selected material was first removed by natural volatilization and aeration that simulated the pretreatment of the prcoess. After that, UV/H₂O₂ oxidation experiments were conducted under various H₂O₂ concentration conditions. Benzene and toluene were mostly volatilized before reaching the oxidation process due to high volatility. Considering the volatility, oxidation experiments were performed at an initial concentration of 5 mg/L for benzene and toluene. The UV/H₂O₂ oxidation process achieved 100% of benzene and toluene removal after 20 minutes under all hydrogen peroxide concentration conditions. The phenol was rarely removed from the volatile experiments and oxidation tests were performed at an initial concentration of 50 mg/L. The process showed 100 % phenol removal after 30 minutes under 0.12 v/v% of hydrogen peroxide concentration condition. Methyl ethyl ketone was removed 58 % after 2 hours of volatile experiments. The process showed 99.7% Methyl ethyl ketone removal after 40 minutes under 0.08 v/v% of hydrogen peroxide concentration condition. It was confirmed that the UV/H₂O₂ process showed high decomposition efficiency for the four selected organic compounds, and identified the amount of hydrogen peroxide in classified organic contaminants.

• Journal of the Korean Vacuum Society
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• v.19 no.2
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• pp.91-95
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• 2010

A UV-enhanced atomic layer deposition (UV-ALD) process was developed to deposit $TiO_2$ thin films on Si substrates using titanium isopropoxide(TIP) and $H_2O$ as precursors with UV light. In the UV-ALD process, the surface reactions were found to be self-limiting and complementary enough to yield a uniform, conformal, pure $TiO_2$ thin film on Si substrates at room temperature. The UV light was very effective to obtain the high-quality $TiO_2$ thin films with good adhesive strength on Si substrates. The UV-ALD process was applied to produce uniform and conformal $TiO_2$ coats into deep trenches with high aspect ratio.

• Advances in environmental research
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• v.3 no.3
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• pp.185-197
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• 2014

Efficient defluorination of perfluorooctanoic acid (PFOA) was achieved by integrating UV irradiation and $Fe^{2+}$ activation of persulfate ($S_2O{_8}^{2-}$). It was found that the UV-$Fe^{2+}$, $Fe^{2+}-S_2O{_8}^{2-}$, and UV-$S_2O{_8}^{2-}$ processes caused defluorination efficiency of 6.4%, 1.6% and 23.2% for PFOA at pH 5.0 within 5 h, respectively, but a combined system of UV-$Fe^{2+}-S_2O{_8}^{2-}$ dramatically promoted the defluorination efficiency up to 63.3%. The beneficial synergistic behavior between $Fe^{2+}-S_2O{_8}^{2-}$ and UV-$S_2O{_8}^{2-}$ was demonstrated to be dependent on $Fe^{2+}$ dosage, initial $S_2O{_8}^{2-}$ concentration, and solution pH. The decomposition of PFOA resulted in generation of shorter-chain perfluorinated carboxylic acids (PFCAs), formic acid and fluoride ions. The generated PFCAs intermediates could be further defluorinated by adding supplementary $Fe^{2+}$ and, $S_2O{_8}^{2-}$ and re-adjusting solution pH in later reaction stage. The much enhanced PFOA defluorination in the UV-$Fe^{2+}-S_2O{_8}^{2-}$ system was attributed to the fact that the simultaneous employment of UV light and $Fe^{2+}$ not only greatly enhanced the activation of $S_2O{_8}^{2-}$ to form strong oxidizing sulfate radicals ($SO{_4}^{\cdot-}$), but also provided an additional decarboxylation pathway caused by electron transfer from PFOA to in situ generated $Fe^{3+}$.

• Food Science and Preservation
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• v.16 no.5
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• pp.636-643
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• 2009

Inactivation by UV-C irradiation of Escherichia coli O157:H7 and Listeria monocytogenes inoculated onto washed carrots was examined. Carrot samples were inoculated with 6-7 log CFU/mL of E. coli O157:H7 or L. monocytogenes, treated with doses of 0, 1, 3, 5, or $10\;kJ/m^2$ UV-C, and stored at $4{\pm}1^{\circ}C$ for 8 d. The populations of E. coli O157:H7 and L. monocytogenes significantly decreased with increasing irradiation dose (p<0.05). In particular, E. coli O157:H7 and L. monocytogenes populations fell significantly by 2.35 and 2.38 log CFU/g at $10\;kJ/m^2$, respectively, compared to control values. UV-C irradiation inhibited color changes and decreased the whiteness index in carrot during storage, compared to controls. Sensory evaluation results showed that UV-C-treated carrots had better sensory characteristics than did the control. Therefore, the results suggest that UV-C irradiation could be useful to improve the microbial safety and sensory qualities of fresh-cut carrots during storage.

• Journal of Environmental Science International
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• v.31 no.8
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• pp.677-689
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• 2022

In order to photocatalytically treat organic matter (COD_Cr) and chromaticity effectively, chemical coagulation and sedimentation processes were employed as a pretreatment of the leachate produced from landfill in Jeju Island. This was performed using FeCl₃·6H₂O as a coagulant. For the treated leachate, UV/TiO₂ and UV/TiO₂/H₂O₂ systems were investigated, using 4 types of UV lamps, including an ozone lamp (24 W), TiO₂ as a photocatalyst, and/or H₂O₂ as an initiator or inhibitor for photocatalytic degradation. In the chemical coagulation and sedimentation process using FeCl₃·6H₂O, optimum removal was achieved with an initial pH of 6, and a coagulant dosage of 2.0 g/L, culminating in the removal of 40% COD_Cr and 81% chromaticity. For the UV/TiO₂ system utilizing an ozone lamp and 3 g/L of TiO₂, the optimum condition was obtained at pH 5. However, the treated COD_Cr and chromaticity did not meet the emission standards (COD_Cr: 400 mg/L, chromaticity: 200 degrees) in a clean area. However, for a UV/TiO₂/H₂O₂ system using 1.54 g/L of H₂O₂ in addition to the above optimum UV/TiO₂ system, the results were 395 mg/L and 160 degrees, respectively, which were within the emission standard limits. The effect of the UV lamp on the removal of COD_Cr, and chromaticity of the leachate decreased in the order of ozone (24 W) lamp > 254 nm (24 W) lamp > ozone (14 W) lamp > 254 nm (14 W) lamp. Only COD_Cr and chromaticity treated with the ozone (24 W) lamp met the emission standards.

• 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.

• Food Engineering Progress
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• v.15 no.1
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• pp.28-33
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• 2011

UV-C and -B types of lamps, and $H_2O_2$ as a photocatalytic material were applied to optimize processing conditions for pesticides removal in Mandarine orange peel. Factors to affect the removal of pestrcides were arranged as a function of irradiation temperature, irradiation time, and $H_2O_2$ spray concentration. The optimum processing conditions for the chloropyrifos and the EPN removals in Mandarine orange peel were irradiation time of 60 min, irradiation temperature of $45^{\circ}C$ and $H_2O_2$ spray concentration of 1000 ppm. However, the optimum processing conditions for methidathion removal were 60 min of irradiation time, $40^{\circ}C$ of irradiation temperature and 1000 ppm of $H_2O_2$ spray concentration. The residual percentages of chloropyrifos, EPN and methidathion were 46, 49 and 28% after above irradiation processing, respectively.