광반응 및 광촉매 반응을 이용한 simazine의 분해 및 독서저감에 관한 연구

김문경,오지윤,손현석,조경덕,Kim, Moon-Kyung,Oh, Ji-Yoon,Son, Hyun-Seok,Zoh, Kyung-Duk 한국환경보건학회 2009 한국환경보건학회지 Vol.35 No.2

The photocatalysis degradation of simazine, s-triazine type herbicide was carried out using circulating photo reactor systems. In order to search for the effective method to mineralize this compound into environmentally compatible products, this study compared the removal efficiencies of simazine by changing various parameters. First, under the photocatalytic condition, simazine was more effectively degraded than by photolysis and $TiO_2$ only condition. With photocatalysis, 5 mg/l simazine was degraded to approximately 90% within 30 min, and completely degraded after 150 min. Ionic byproducts such as ${NO_2}^-$, ${NO_3}^-$, and $Cl^-$ were detected from the photocatalysis of simazine, however, the recoveries were poor, indicating the presence of organic intermediates rather than the mineralization of simazine during photocatalysis. Two bioassays using V. fischeri and D. magna were employed to measure the toxicity reduction in the reaction solutions treated by both photocatalysis and photolysis. Simazine and its photocatalysis treated water did not exert any significant toxicity to V. fischeri, marine bacterium. However, the acute toxicity test using D. magna indicates that initial acute toxicity ($EC_{50}$ = 57.30%) was completely reduced ($EC_{50}$ = 100%) after 150 min under both photocatalysis and photoysis of simazine. This results indicates that photocatalysis and photolysis of simazine reduced the acute toxicity through mineralization.

Plasmonic photocatalyst-like fluorescent proteins for generating reactive oxygen species

Leem Jung Woo,Kim Seong-Ryul,Choi Kwang-Ho,Kim Young L. 나노기술연구협의회 2018 Nano Convergence Vol.5 No.8

The recent advances in photocatalysis have opened a variety of new possibilities for energy and biomedical applications. In particular, plasmonic photocatalysis using hybridization of semiconductor materials and metal nanoparticles has recently facilitated the rapid progress in enhancing photocatalytic efficiency under visible or solar light. One critical underlying aspect of photocatalysis is that it generates and releases reactive oxygen species (ROS) as intermediate or final products upon light excitation or activation. Although plasmonic photocatalysis overcomes the limitation of UV irradiation, synthesized metal/semiconductor nanomaterial photocatalysts often bring up biohazardous and environmental issues. In this respect, this review article is centered in identifying natural photosensitizing organic materials that can generate similar types of ROS as those of plasmonic photocatalysis. In particular, we propose the idea of plasmonic photocatalyst-like fluorescent proteins for ROS generation under visible light irradiation. We recapitulate fluorescent proteins that have Type I and Type II photosensitization properties in a comparable manner to plasmonic photocatalysis. Plasmonic photocatalysis and protein photosensitization have not yet been compared systemically in terms of ROS photogeneration under visible light, although the phototoxicity and cytotoxicity of some fluorescent proteins are well recognized. A comprehensive understanding of plasmonic photocatalyst-like fluorescent proteins and their potential advantages will lead us to explore new environmental, biomedical, and defense applications.

광촉매 반응 시스템에서 오존을 이용한 VOC 및 악취 제거에 관한 연구

정규철 ( Jeong Gyu Cheol ),홍성창 ( Hong Seong Chang ) 한국공업화학회 2003 공업화학 Vol.14 No.5

최근 가장 중요한 기술적이 문제 중의 하나는 대기 내의 휘발성 유기화합물(VOC) 및 악취의 효과적이고 경제적인 처리일 것이다. 본 연구에서는 acetone, MIBK, benzene, ammonia를 대상으로 광촉매 반응에서 오존의 영향을 조사하였으며, 시스템을 photocatalysis, O₃-photocatalysis, O₃/photocatalysis로 구분하여 연구를 수행하였다. 광촉매 반응 시 오존의 영향은 분해 대상가스에 따라 달리 나타났으며 광촉매 반응에 의한 오존의 분해를 고려하여 일정 농도 이상의 오존이 필요하였다. 특히 오존은 방향족 유기화합물인 benzene의 분해에 큰 영향을 주는 것을 알 수 있었으며, 또한 ammonia의 중간생성물질인 NO를 NO₂로 산화시키는 작용을 하는 것을 확인할 수 있었다. 그리고 분해 대상가스마다 각기 다른 시스템에서 최적 반응을 보임을 알 수 있었다. One of the most important technical issues of recent years is the effective and economical disposal of volatile organic compounds (VOC) and odor in air. The present study examined the effectiveness of ozone for the photocatalytic reaction of common and toxic VOCs including acetone, MIBK, benzene, and ammonia in the gas phase. The systems were divided into photocatalysis, O_(3)-photocatalysis, and O_(3)photocatalysis. The effect of ozone was different according to the type of VOC and odor. Because of the degradation of ozone was based on the photocatalytic reaction, ozone beyond a certain concentration was needed. Especially, ozone affected the degradation of benzene, an aromatic organic compound and oxidized NO, an intermediate in ammonia process. to NO_(2). The optimum system for the degradation of VOC and odor was different according to the type of VOC and odor.

나노-TiO₂ 입자로 코팅된 다공성 담체의 광촉매 반응에 관한 동력학

박성준(Seong Jun Park),Bruce E. Rittmann,배우근(Woo Keun Bae) 大韓環境工學會 2009 대한환경공학회지 Vol.31 No.10

난분해성 및 독성 폐수 처리는 고급산화 기술과 생물학적 처리가 친화결합(intimate coupling) 을 이룰 때 최적의 효과를 거둘 수 있다. 본 연구에서는 광촉매 산화와 생물학적 처리를 친화결합하도록 고안된 다공성 TiO₂ 코팅 담체를 제조하여 광촉매 반응에 관한 동력학 연구를 수행하였다. 저온 sol-gel 코팅법으로 제조된 PVA 재질의 다공성 TiO₂ 담체는 UV 조사하에서 methylene blue (MB)를 효율적으로 분해하였다. 시험 농도(최대 100 μM)에서 MB의 흡착속도는 1차반응 (first-order reaction)의 성질을 보였으며, 흡착과 산화를 포함한 총반응속도는 유사 Langmuir 모델로 예측 가능하였다. 이러한 원인은 담체 표면에 MB가 흡착됨에 따라 UV 조사에 의하여 광촉매 반응이 일어날 표면이 줄어들었기 때문인 것으로 판단된다. 다공성 TiO₂ 담체의 단위 TiO₂ 량당 최대 MB 제거속도는 슬러리 TiO₂ 반응기에서 얻은 MB 제거속도보다 4배 더 빨랐다. 본 연구로 인하여 저온 sol-gel 코팅법으로 제조한 PVA 재질 다공성 TiO₂ 담체가 성공적인 광분해 반응을 나타내는 것이 확인되었으며, 동 담체에 대한 광촉매 반응의 동력학적 성질이 구명되어, 향후 생물처리를 친화결합 시킬 수 있는 연구 바탕을 확보하였다. Toxic and recalcitrant organic pollutants in wastewaters can be effectively treated when advanced oxidation and biodegradation are combined, ideally with intimate coupling, in which both processes occur simultaneously in the same system. One means to achieve intimate coupling is to coat nanoscale TiO₂ on the outside of macroporous biofilm carriers. This study investigated the kinetics of photocatalysis with TiO₂-coated porous carriers. The carriers were made of polyvinyl alcohol (PVA) and coated with TiO₂ using a low-temperature sol-gel process. The TiO₂-coated carriers catalyzed the oxidation of methylene blue (MB) effectively under irradiation of UV light. The overall reaction rate with adsorption and photolysis saturated at high MB concentration, and approached the adsorption rate, which was first order for all MB concent rations. This result indicates that adsorbed MB may have slowed photocatalysis by blocking active sites for photocatalysis. The overall kinetics could be described by a quasi-Langmuir model. The estimated maximum specific (per unit mass of TiO₂) transformation rate of MB by the TiO₂-coated carriers was four times larger than that obtained from slurry-TiO₂ reactors. This observation demonstrated that the TiO₂ present as a coating on the carriers maintained high efficiency for transforming recalcitrant organic matter via photocatalysis. These findings serve as a foundation for advancement of an intimate coupling of photocatalysis to biodegradation.

Photocatalytic Degradation of Methyl tert-Butyl Ether (MTBE): A review

Seddigi, Zaki S.,Ahmed, Saleh A.,Ansari, Shahid P.,Yarkandi, Naeema H.,Danish, Ekram,Oteef, Mohammed D.Y.,Cohelan, M.,Ahmed, Shakeel,Abulkibash, Abdallah M. Techno-Press 2014 Advances in environmental research Vol.3 No.1

Advanced oxidation processes using UV and catalysts like $TiO_2$ and ZnO have been recently applied for the photocatalytic degradation of MTBE in water. Attempts have been made to replace the UV radiation by the solar spectrum. This review intends to shed more light on the work that has been done so far in this area of research. The information provided will help in crystallizing the ideas required to shift the trend from UV photocatalysis to sunlight photocatalysis. The careful optimization of the reaction parameters and the type of the dopant employed are greatly responsible for any enhancement in the degradation process. The advantage of shifting from UV photocatalysts to visible light photocatalysts can be observed when catalysts like $TiO_2$ and ZnO are doped with suitable metals. Therefore, it is expected that in the near future, the visible light photocatalysis will be the main technique applied for the remediation of water contaminated with MTBE.

Photocatalysts Consisting of WS₂ Nanosheets and Pd Nanoparticles for Visible Light Photocatalysis

( Faizan Raza ),박정현,이혜림,임다빈,김종호 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1

WS₂ nanosheets are photoactive 2D-nanomaterials that have great potential in conversion of solar energy to visible light driven catalytic reactions. Decorating WS₂ nanosheets with metal nanoparticles (NPs) is one of the effective ways to tune their intrinsic properties for visible light photocatalysis. Herein, WS₂ nanosheets decorated with Pd NPs (WS₂/Pd NPs) were effectively prepared by a simple and green reduction reaction using bath sonication at room temperature. WS₂/Pd NPs were successfully applied to Suzuki C-C coupling reactions under visible light at room temperature, showing outstanding photocatalytic activity (yields > 95 %, TOF of 1130 h^-1).

Simultaneous monitoring of photocatalysis of three pharmaceuticals by immobilized TiO₂ nanoparticles: Chemometric assessment, intermediates identification and ecotoxicological evaluation

Khataee, A.R.,Fathinia, M.,Joo, S.W. Pergamon 2013 Spectrochimica acta. Part A, Molecular and biomole Vol.112 No.-

<P>In this study, the photocatalytic degradation of a mixture of three pharmaceuticals, Metronidazole (MET), Atenolol (ATL) and Chlorpromazine (CPR), was quantified simultaneously during the UV/TiO2 process. The investigated TiO2 was Millennium PC-500 immobilized on ceramic plates by sol-gel based method. The partial least squares modeling was successfully applied for the multivariate calibration of the spectrophotometric data. The central composite design was applied to model and optimize the UV/TiO2 process. Predicted values of removal efficiency were found to be in good agreement with experimental values for MET, ATL and CPR (R-2 = 0.947 and Adj-R-2 = 0.906, R-2 = 0.977 and Adj-R-2 = 0.960 and R-2 = 0.982 and Adj-R-2 = 0.969, respectively). The optimum initial concentration of pharmaceuticals, reaction time and UV light intensity was found to be 10 mg L-1, 150 min and 38.45 W m(-2), respectively. The main degradation intermediates of pharmaceuticals produced in this process were identified by GC-MS technique. The chronic ecotoxicity of pharmaceuticals was evaluated using aquatic species Spirodela polyrrhiza prior to and after photocatalysis. The TOC results (90% removal after 16 h) and ecotoxicological experiments revealed that the photocatalysis process could effectively mineralize and reduce the ecotoxicity of the pharmaceuticals from their aqueous solutions. (C) 2013 Elsevier B.V. All rights reserved.</P>

Sonophotocatalysis와 Photocatalysis를 이용한 Chloroform의 광산화

박재홍 ( Jae Hong Park ),조일형 ( Il Hyoung Cho ) 한국물환경학회 2005 한국물환경학회지 Vol.21 No.3

Comparison between photocatalysis (UV+TiO₂) and sonophotocatalysis (Sonication+UV+TiO₂) were performed in lab-scale experiments for the treatment of chloroform. The effect of operational parameters, i.e., initial chloroform concentration, TiO₂ concentration, UV light intensity and sonication time on the degradation rate of aqueous solution of chloroform has been examined. The optimal conditions for photocatalysis and sonophotocatalysis processes were determined: initial chloroform concentration was 25 ㎎/L, the concentration of TiO₂ was 200 ㎎/L and UV light intensity was 6.630 mW/㎠, respectively. The optimal sonication time on sonophotocatalysis process was 90 min. Under the optimal conditions, sonophotocatalysis was effective for inducing faster degradation of the chloroform.

Adsorption and Photocatalysis of Spherical TiO₂ Particles Prepared by Hydrothermal Reaction

( Heung-joe Jung ) 조선대학교 공학기술연구원 2017 공학기술논문지 Vol.10 No.4

TiO₂ spherical particles were prepared using hydrothermal reaction at different temperatures of 110, 150 and 190℃ for 5 h. The TiO₂ samples were characterized by BET, XRD and SEM analysis. Specific surface areas and particle sizes are in the range of 148 ~ 240 m²g^-1 and 323 - 450 nm, composed of tiny nanoparticles with size of 5 ~ 7 nm. It was found that photocatalytic degradation of methylene blue is highly sensitive to particle sizes on the adsorption and photocatalysis.

Visible and near infrared light active photocatalysis based on conjugated polymers

THE KOREAN SOCIETY OF INDUSTRIAL AND ENGINEERING 2017 Journal of Industrial and Engineering Chemistry Vol.51 No.-

<P><B>Abstract</B></P> <P>Conjugated polymers have been used to produce solar energy conversion materials in photovoltaics due to their outstanding light harvesting properties and low-cost processing. However, their photocatalytic activity has only recently been highlighted with the preparation of robust, metal-free, and visible or near-infrared light active photocatalysts. This review describes why the study of photocatalysis based on conjugated polymers has become vivid these days in comparison to inorganic or metal-based photocatalysts, and further illustrates the developed technologies concerning exclusively conjugated polymers but also hybrid structures. The different forms of the conjugated polymer photocatalysts include linear, graphitic C,N-based, porous, nanostructured, and coordinated polymers or polymers with units made of small molecular dye structures. The hybrid systems contain combinations of conjugated polymers with graphene, metals, or metal oxides. A perspective on the challenges posed by the future exploration of photocatalysts based on conjugated polymers is also provided, covering the inherent instability issues of conjugated polymers during the harsh photocatalytic reaction conditions. This review aims to provide an insight for the utilization of conjugated polymers in the fields of photocatalysis, energy conversion, and environment-friendly applications of solar energy.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Conjugated polymers are prominent metal-free photocatalysts. </LI> <LI> Conjugated polymers are promising for visible- and near infrared-active photocatalysis. </LI> <LI> Linear, graphitic, porous, nanostructured and coordinated polymers are described. </LI> <LI> Hybrid systems with nanocarbons, metals and metal oxides enhance photocatalytic activities. </LI> <LI> Inherent instability of conjugated polymer-based photocatalysts is also addressed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>