• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.311-324
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• 2018

Herein,the Neodymium ion ($Nd^{3+}$) doped CoAl-LDH have been successfully prepared via co-precipitation method and was used as a precursor of Nd-doped CoAl-mixed metal oxides (MMO). The photocatalytic activity of doped LDH and MMO was investigated in the degradation of an azo dye, C.I. Acid Red 14, under visible light irradiation. DRS and PL analysis demonstrated decreasing in the band gap energy and recombination of photo-induced charge carriers of Nd-doped LDH and MMO compared with the pristine CoAL-LDH. Due to significant difference in photocatalytic performance. A power law empirical kinetic model was obtained for predicting the photocatalytic degradation efficiency.

• 한국수소및신에너지학회논문집
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• 제26권3호
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• pp.247-259
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• 2015

This study was performed to investigate the application of dark $H_2$ fermentation to two-stage bioprocesses for organic waste treatment and energy production. We reviewed information about the two-stage bioprocesses combining dark $H_2$ fermentation with $CH_4$ fermentation, photo $H_2$ fermentation, microbial fuel cells (MFCs), or microbial electrolysis cells (MECs) by using academic information databases and university libraries. Dark fermentative bacteria use organic waste as the sole source of electrons and energy, converting it into $H_2$. The reactions related to dark $H_2$ fermentation are rapid and do not require sunlight, making them useful for treating organic waste. However, the degradation is not complete and organic acids remain. Thus, dark $H_2$ fermentation should be combined with a post-treatment process, such as $CH_4$ fermentation, photo $H_2$ fermentation, MFCs, or MECs. So far, dark $H_2$ fermentation followed by $CH_4$ fermentation is a promising two-stage bioprocess among them. However, if the problems of manufacturing expenses, operational cost, scale-up, and practical applications will be solved, the two-stage bioprocesses combining dark $H_2$ fermentation with photo $H_2$ fermentation, MFCs, or MECs have also infinite potential in organic waste treatment and energy production. This paper demonstrated the feasibility of two-stage bioprocesses combining dark $H_2$ fermentation as a novel system for organic waste treatment and energy production.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
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• pp.387-392
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• 2005

For the production of further functional bio-degradable plastic(polybutylene succinate:PBS) with $TiO_{2}$ as photocatalyst, which shows the decomposition of detrimental organic compound and pollutant under ultraviolet irradiation, we attempted to prepare $TiO_{2}$ coatings on PBS substrate by HVOF and plasma spraying techniques under various conditions. The microstructures of coatings were characterized with SEM and XRD analysis, and the photocatalytic efficiency of coatings was evaluated through the photo degradation of gaseous acetaldehyde. The effects of primary particle size and spraying parameters on the formation behavior, photo catalytic performance and mechanical characteristics of the coatings have been investigated. The results indicated that with respect to both the HVOF sprayed $P_{200}$ and $P_{30}$ coatings, the high anatase ratio off 100% can be achieved regardless of fuel gas pressure. On the other hand, the HVOF sprayed $P_{7}$ coating exhibited largely decreased anatase ratio (from 100% to 49.1%) with increasing the fuel gas pressure, which may be attributed to the much higher susceptibility to heat of 7nm agglomerated powder. In terms of photocatalytic efficiency, HVOF sprayed $P_{200}$ and $P_{30}$ coatings seem to predominate as compared to that of plasma sprayed $P_{200}$ coatings owing to the higher anatase ratio. However, the HVOF sprayed $P_{7}$ coatings didn't show the photo catalytic activity, which may result from the extremely small reaction surface area to the photo-catalytic activity and low anatase ratio. Such functional PBS with new roles is expected to cosiderably contribute to the reduction of aggravated environmel problem.

• 한국산학기술학회논문지
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• 제14권10호
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• pp.5304-5309
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• 2013

methylethylketone(MEK)의 광분해 특성을 연속식 단일관형태의 광촉매반응기를 이용하여 연구하였다. 연속식 광촉매반응기에 적용된 주요 반응변수는 MEK의 초기농도, 광세기, 장기운전의 영향이었다. MEK의 주입농도가 증가할수록 광분해 효율은 감소하였으며, 광분해 감소의 폭은 높은 유속에서 더욱 두드러졌다. 동일한 체류시간의 조건에서 광반응기의 직경과 UV램프의 파장이 증가할수록 MEK제거효율은 감소하였다. 연속식 광촉매반응기를 120시간 연속적으로 운전하여도 MEK 제거효율에서의 감소는 없었다.

• Journal of Industrial and Engineering Chemistry
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• 제67권
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• pp.164-174
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• 2018

The purpose of this work designed hybrid-structured and plasma effect photocatalyst of $Ag/In_2O_3/TiO_2/HNTs$ via sol-gel and photo-reduction methods. The structures, morphologies, optical and photoelectric performances of as-prepared photocatalysts were characterized via XRD, TEM, XPS, BET, UV-vis DRS, PL and photocurrents. The photocatalytic activity was evaluated by degradation of TC. The results showed that the hybrid-structure and plasma effect can effectively cause the multi-transfer of electrons and increase the separation rate of electron and hole pairs which obtained high photocatalytic activity. The photocatalytic degradation processes reveal that $^{\bullet}O_2{^-}$ and $h^+$ are major active species.

• 한국환경과학회지
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• 제15권2호
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• pp.121-131
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• 2006

Atmospheric bulk (wet and dry) samples were monthly collected in Masan and Heangam areas of Korea, to assess the deposition flux and seasonal variation of polycyclic aromatic hydrocarbons (PAHs). Deposition fluxes of PAHs in bulk samples were determined using gas chromatography coupled to mass spectrometer detector (GC/MSD). Particle deposition fluxes from Masan and Haengam areas varied from 13 to $87\;g/m^2/year$ and from 5 to $52\;g/m^2/year$, respectively. PAHs deposition fluxes in atmospheric bulk samples in Masan and Haengam areas ranged from 135 to $464\;{\mu}g/m^2/year$ and from 62.2 to $194\;{\mu}g/m^2/year$, respectively. Atmospheric deposition fluxes of particles and PAHs in this study were comparable to or slightly lower values than those from different locations in Korea and other countries. PAHs profiles of atmospheric deposition bulk samples showed slightly different from two sampling areas, however the predominant species of PAHs were similar. Indeno (1,2,3-c,d)pyrene, benzo(g,h,i)perylene, phenanthrene compounds were the most detected PAHs in deposition bulk samples. Carcinogenic PAHs occupied the contribution of approximately $30-40\%$ of the total PAHs deposition fluxes. The non-metric multi-dimensional scaling (MDS) was used, to assess the differentiation of PAHs source between two sampling areas. The result suggests that PAHs contamination sources were different according to the location and season surveyed. There was no an apparent relationship between the PAHs deposition flux against temperature and rainfall amount, even though summer season with the highest temperature and the largest amount of precipitation showed the lowest PAHs deposition flux. Benzo(e)pyrene/benzo(a)pyrene ratio indicated that the photo-degradation process was one of important factors to the seasonal variation of PAHs with the lower deposition fluxes.

• Applied Biological Chemistry
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• 제43권2호
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• pp.130-135
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• 2000

유기인계 살충제 flupyrazofos의 수중 광분해 양상을 관찰하고자 다양한 조건에서 광분해율 및 분해 반감기 등을 조사하였다. 순수한 증류수 중에서 flupyrazofos는 광에 매우 안정하여 단순한 가수분해에 의한 감소가 관찰된 반면 감광제로 알려진 acetone처리 후 자연광 하에서 광분해율의 변화를 측정한 결과, 수중에 acetone의 함량이 0.047%, 몰 비가 0.006 이상이 되는 경우 flupyrazofos에 대한 광분해 촉진 효과가 발생할 것으로 예측할 수 있었다. Acetone이 처리된 경우, flupyrazofos의 광분해 반응은 광산화제인 singlet oxygen에 의해 분해율이 크게 영향 받는 것으로 확인되었으나 hydroxyl radical의 영향은 확인되지 않았다. Actinometer실험에서 2% acetone을 처리한 0.4ppm flupyrazofos의 양자수율(quantum yield)은 $17.66{\times}10^{-5}$이었으며 이때의 분해속도 상수는 0.038/hour이며, 분해 반감기는 18.2시간이었다.

• 한국재료학회지
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• 제27권9호
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• pp.489-494
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• 2017

ZnS powder was synthesized using a relatively facile and convenient glycothermal method at various reaction temperatures. ZnS was successfully synthesized at temperatures as low as $125^{\circ}C$ using zinc acetate and thiourea as raw materials, and diethylene glycol as the solvent. No mineralizers or precipitation processes were used in the fabrication, which suggests that the spherical ZnS powders were directly prepared in the glycothermal method. The phase composition, morphology, and optical properties of the prepared ZnS powders were characterized using XRD, FE-SEM, and UV-vis measurements. The prepared ZnS powders had a zinc blende structure and showed average primary particles with diameters of approximately 20~30 nm, calculated from the XRD peak width. All of the powders consisted of aggregated secondary powders with spherical morphology and a size of approximately $0.1{\sim}0.5{\mu}m$; these powders contained many small primary nanopowders. The as-prepared ZnS exhibited strong photo absorption in the UV region, and a red-shift in the optical absorption spectra due to the improvement in powder size and crystallinity with increasing reaction temperature. The effects of the reaction temperature on the photocatalytic properties of the ZnS powders were investigated. The photocatalytic properties of the as-synthesized ZnS powders were evaluated according to the removal degree of methyl orange (MO) under UV irradiation (${\lambda}=365nm$). It was found that the ZnS powder prepared at above $175^{\circ}C$ exhibited the highest photocatalytic degradation, with nearly 95 % of MO decomposed through the mediation of photo-generated hydroxyl radicals after irradiation for 60 min. These results suggest that the ZnS powders could potentially be applicable as photocatalysts for the efficient degradation of organic pollutants.

• 한국재료학회지
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• 제20권8호
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• pp.429-433
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• 2010

In this study, activated carbon (AC) as a carbon source was modified with different concentrations of cobalt chloride ($CoCl_2$) to prepare a Co-AC composite, and it was used for the preparation of Co-AC/$TiO_2$ composites with titanium oxysulfate (TOS) as the titanium precursor. The physicochemical properties of the prepared Co-AC/$TiO_2$ composites were characterized by $N_2$ adsorption at 77 K, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis. The photocatalytic treatments of organic dyes were examined under an irradiation of visible light with different irradiation times. $N_2$ adsorption data showed that the composites had decreased surface area compared with the pristine AC, which was $389\;m^2/g$. From the XRD results, the Co-AC/$TiO_2$ composites contained a mixturephase structuresof anatase and rutile, but a cobalt oxide phase was not detected in the XRD pattern. The EDX results of the Co-AC/$TiO_2$ composites confirmed the presence of various elements, namely, C, O, Ti, and Co. Subsequently, the decomposition of methylene orange (MO, $C_{14}H_{14}N_3NaO_3S$) and rhodamine B (Rh.B, $C_{28}H_{31}ClN_2O_3$) in an aqueous solution, respectively, showed the combined effects of an adsorption effect by AC and the photo degradation effect by $TiO_2$. Especially, the Co particles in the Co-AC/$TiO_2$ composites could enhance the photo degradation behaviors of $TiO_2$ under visible light.

• Bulletin of the Korean Chemical Society
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• 제31권6호
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• pp.1589-1595
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• 2010

In order to effective degradation of organic dye both under visible light or ultrasonic irradiation, the MWCNTs (multiwalled carbon nanotube) deposited with Fe and $TiO_2$ were prepared by a modified sol-gel method. The Fe/$TiO_2$-MWCNT catalyst was characterized by surface area of BET, scanning electron microscope (SEM), Transmission Electron Microscope (TEM), X-ray diffraction (XRD), and energy dispersive X-ray (EDX) and ultraviolet-visible (UV-vis) spectroscopy. The low intensity visible light and low power ultrasound was as an irradiation source and the methylene blue (MB) was choose as the model organic dye. Then degradation experiments were carried out in present of undoped $TiO_2$, Fe/$TiO_2$ and Fe/$TiO_2$-MWCNT catalysts. Through the degradation of MB solution, the results showed the feasible and potential use of Fe/$TiO_2$-MWCNT catalyst under visible light and ultrasonic irradiation due to the enhanced formation of reactive radicals as well as the possible visible light and the increase of ultrasound-induced active surface area of the catalyst. After addition of $H_2O_2$, the MB degradation rates have been accelerated, especially with Fe/$TiO_2$-MWCNT catalyst, in case of that the photo-Fenton reaction occurred. The sonophotocatalysis was always faster than the respective individual processes due to the more formation of reactive radicals as well as the increase of the active surface area of Fe/$TiO_2$-MWCNT catalyst.