Effect of nitrate, carbonate/bicarbonate, humic acid, and H₂O₂ on the kinetics and degradation mechanism of Bisphenol-A during UV photolysis

Kang, Young-Min,Kim, Moon-Kyung,Zoh, Kyung-Duk Elsevier 2018 CHEMOSPHERE - Vol.204 No.-

<P><B>Abstract</B></P> <P>In this study, the effects of natural water components (nitrate, carbonate/bicarbonate, and humic acid) on the kinetics and degradation mechanisms of bisphenol A (BPA) during UV-C photolysis and UV/H<SUB>2</SUB>O<SUB>2</SUB> reaction were examined. The presence of NO<SUB>3</SUB> <SUP>−</SUP> (0.04–0.4 mM) and CO<SUB>3</SUB> <SUP>2−</SUP>/HCO<SUB>3</SUB> <SUP>−</SUP> (0.4–4 mM) ions increased BPA degradation during UV photolysis. Humic acid less than 3 mg/L promoted BPA degradation, but greater than 3 mg/L of humic acid inhibited BPA degradation. During the UV/H<SUB>2</SUB>O<SUB>2</SUB> reaction, all water matrix components acted as radical scavengers in the order of humic acid > CO<SUB>3</SUB> <SUP>2−</SUP>/HCO<SUB>3</SUB> <SUP>−</SUP> > NO<SUB>3</SUB> <SUP>−</SUP>. All of the degradation reactions agreed with the pseudo-first-order kinetics. While eight byproducts (<I>m</I>/<I>z</I> = 122, 136, 139, 164, 181, 244, 273, 289) were identified in UV-C/NO<SUB>3</SUB> <SUP>−</SUP> photolysis reaction, four (<I>m</I>/<I>z</I> = 122, 136, 164, 244) and three byproducts (<I>m</I>/<I>z</I> = 122, 136, 164) were observed during UV-C/NO<SUB>3</SUB> <SUP>−</SUP>/CO<SUB>3</SUB> <SUP>2−</SUP>/HCO<SUB>3</SUB> <SUP>−</SUP> and UV-C/CO<SUB>3</SUB> <SUP>2−</SUP>/HCO<SUB>3</SUB> <SUP>−</SUP> reactions. Nitrogenated and hydrogenated byproducts were first observed during the UV-C/NO<SUB>3</SUB> <SUP>−</SUP> photolysis, but only hydrogenated byproducts as adducts were detected during the UV-C/NO<SUB>3</SUB> <SUP>−</SUP>/CO<SUB>3</SUB> <SUP>2−</SUP>/HCO<SUB>3</SUB> <SUP>−</SUP> photolysis. Nitrogenated and hydrogenated byproducts were formed in the early stage of degradation by OH or NO<SUB>2</SUB> radicals, and these byproducts were subsequently degraded into smaller compounds with further reaction during UV-C/NO<SUB>3</SUB> <SUP>−</SUP> and UV-C/NO<SUB>3</SUB> <SUP>−</SUP>/CO<SUB>3</SUB> <SUP>2−</SUP>/HCO<SUB>3</SUB> <SUP>−</SUP> reactions. In contrast, BPA was directly degraded into smaller compounds by β-scission of the isopropyl group by CO<SUB>3</SUB> <SUP>−</SUP>/HCO<SUB>3</SUB> radicals during UV-C/CO<SUB>3</SUB> <SUP>2−</SUP>/HCO<SUB>3</SUB> <SUP>−</SUP> reaction. Our results imply that the water components can change the degradation mechanism of BPA during UV photolysis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> NO<SUB>3</SUB> <SUP>−</SUP> and CO<SUB>3</SUB> <SUP>2−</SUP>/HCO<SUB>3</SUB> <SUP>−</SUP> ions acted only as a promoter for UV-C photolysis of BPA. </LI> <LI> Humic acid acted as both promoter and scavenger for UV-C photolysis of BPA. </LI> <LI> NO<SUB>3</SUB> <SUP>−</SUP>, CO<SUB>3</SUB> <SUP>2−</SUP>/HCO<SUB>3</SUB> <SUP>−</SUP> ions, and humic acid inhibited the BPA degradation during UV-C/H<SUB>2</SUB>O<SUB>2</SUB>. </LI> <LI> Nitrogenated and hydrogenated byproducts were observed during UV-C/NO<SUB>3</SUB> <SUP>−</SUP> reaction. </LI> <LI> The BPA degradation mechanisms of UV photolysis of BPA were proposed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Degradation kinetics and pathways of β-cyclocitral and β-ionone during UV photolysis and UV/chlorination reactions

Kim, Taeyeon,Kim, Tae-Kyoung,Zoh, Kyung-Duk Elsevier 2019 Journal of environmental management Vol.239 No.-

<P><B>Abstract</B></P> <P>β-cyclocitral and β-ionone are ones of major algal odorants produced by oxidation of the β-carotene that exists in algae cells. These compounds degraded the quality of drinking water therefore it needed to be treated in drinking water treatment by advanced oxidation processes. In this study, UV photolysis and UV-chlorination reactions along with chlorination to remove these odorants in water were compared. Kinetics of three reactions were well fitted at pseudo-first order model. Among three reactions, UV-chlorination was the most effective due to generation of OH and Cl radicals. β-ionone showed faster degradation compared to β-cyclocitral due to the existence of double bond in the alkyl carbon chain. In addition, radical contributions of degradation of odorants were examined. During UV-chlorination, UV photolysis contributed around 50% of removal for two odorants. OH radical took part of 36% removal of β-ionone and 50% removal of β-cyclocitral. Unlike β-ionone, β-cyclocitral was not degraded by reactive chlorine species during UV-chlorination. Acidic pH was favorable for UV-chlorination due to different quantum yield and radical scavenging effect by chlorine species. Formation of trace amount of chloroform was observed during UV-chlorination. The methyl ketone group of β-ionone was the main site for chloroform production. Several byproducts during UV photolysis and UV-chlorination of β-ionone were identified by GC-MS, and these were degraded with further reaction by UV-induced isomerization, OH radical, and bond scission mechanisms. β-cyclocitral was formed as byproducts during UV-chlorination of β-ionone. Based on degradation byproducts, the degradation pathways of β-ionone and β-cyclocitral of UV photolysis and UV-chlorination were suggested based on the identified byproducts. This study showed UV-chlorination process can be applied for degrading odorants like β-cyclocitral and β-ionone.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The removals of two odorants during UV photolysis and UV-chlorination was examined. </LI> <LI> Acidic pH was favorable for UV-chlorination of β-cyclocitral and β-ionone. </LI> <LI> UV-chlorination of odorant was achieved by UV photolysis, OH and Cl radicals. </LI> <LI> Degradation pathways of β-cyclocitral and β-ionone during reactions were proposed. </LI> <LI> UV-chlorination can be an option for treating algal odorant in water treatment plants. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Degradation mechanism of anatoxin-a in UV-C/H₂O₂ reaction

Tak, So-Yeon,Kim, Moon-Kyung,Lee, Jung-Eun,Lee, Young-Min,Zoh, Kyung-Duk Elsevier 2018 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.334 No.-

<P><B>Abstract</B></P> <P>In this study, the kinetics and removal mechanism of anatoxin-a (C<SUB>10</SUB>H<SUB>15</SUB>NO) during a UV-C/H<SUB>2</SUB>O<SUB>2</SUB> reaction were investigated. The removal of anatoxin-a was more effective during a UV-C/H<SUB>2</SUB>O<SUB>2</SUB> reaction than with either UV photolysis or H<SUB>2</SUB>O<SUB>2</SUB> alone, due to the effective production of hydroxyl (OH) radicals. The UV-C/H<SUB>2</SUB>O<SUB>2</SUB> reaction of anatoxin-a resulted in an approximately 60% decrease in total organic carbon (TOC) within 420 min, while 45% of the carbon in anatoxin-a was converted into acetate, and most of the nitrogen in anatoxin-a was converted into NH<SUB>4</SUB> <SUP>+</SUP>, NO<SUB>2</SUB> <SUP>−</SUP>, and NO<SUB>3</SUB> <SUP>−</SUP> ions. More than 50% of the nitrogen in anatoxin-a was mineralized, mainly into NO<SUB>3</SUB> <SUP>−</SUP> ions, and complete nitrogen recovery was achieved after 120 min of the UV-C/H<SUB>2</SUB>O<SUB>2</SUB> reaction. Using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS), we identified six degradation by-products in the UV-C/H<SUB>2</SUB>O<SUB>2</SUB> reaction ([M+H]<SUP>+</SUP> = 142, 127, 113, 132, 117, and 124, respectively), which were further degraded as the reaction continued. Using these by-products, we proposed a degradation pathway for anatoxin-a during the UV-C/H<SUB>2</SUB>O<SUB>2</SUB> reaction. Our results indicate that anatoxin-a can be effectively removed by a UV-C/H<SUB>2</SUB>O<SUB>2</SUB> reaction during water treatment processes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Removal of anatoxin-a was effective during UV-C/H<SUB>2</SUB>O<SUB>2</SUB> reaction. </LI> <LI> NH<SUB>4</SUB> <SUP>+</SUP>, NO<SUB>2</SUB> <SUP>−</SUP>, and NO<SUB>3</SUB> <SUP>−</SUP> ions were produced as nitrogen byproducts in UV/H<SUB>2</SUB>O<SUB>2</SUB> reaction. </LI> <LI> Acetate was produced as a carbon short chain byproduct from anatoxin-a. </LI> <LI> Six degradation byproducts during UV-C/H<SUB>2</SUB>O<SUB>2</SUB> reaction were newly identified. </LI> <LI> The degradation pathway of anatoxin-a during UV-C/H<SUB>2</SUB>O<SUB>2</SUB> reaction was proposed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

광산화 및 광촉매 공정에서 VOCs의 산화반응 속도 산출에 관한 연구

정창훈,이경호 한국환경과학회 2004 한국환경과학회지 Vol.13 No.1

In this study, the decomposition of gas-phase TCE, Benzene and Toluene, in air streams by direct UV Photolysis and UV/TiO₂ process was studied. For direct UV Photolysis, by regressing with computer calculation to the experimental results the value of reaction rate constant k of TCE, Toluene and Benzene in this work were determined to be 0.00392s^(-1), 0.00230s^(-1) and 0.00126s^(-1), respectively. And the adsorption constant K of TCE, Toluene and Benzene in this work were determined to be 0.0519mo1^(-1) ,0.0313mo1^(-1) and 0.0084mo1^(-1), respectively. For W/TiO₂ system by regressing with computer calculation to the experimental results the value of reaction rate constant k of TCE, Toluene, and Benzene in this work were determined to be 5.74g/ℓ · min, 3.85g/ℓ · min, and 1.18g/ℓ · min, respectively. And the catalyst adsorption constant K of TCE, Toluene, and Benzene in this work were determined to be 0.0005m³/㎎, 0.0043m³/㎎ and 0.0048m³/㎎, respectively.

The UV/H₂O₂ Photodegradation of Nitrogen Containing Organic compounds in water

Aqeel Afzal(아킬아프잘),Atta Ullah(아타울라),Atif Khan(아티프칸),Lim Ho-Jin(임호진) 대한환경공학회 2020 대한환경공학회 학술발표논문집 Vol.2020 No.11

해수의 염 농도와 탁도가 전기, UV 및 전기+UV 공정의 Artemia sp. 불활성화에 미치는 영향

김동석 ( Dong-seng Kim ),박영식 ( Young-seek Park ) 한국환경과학회 2019 한국환경과학회지 Vol.28 No.3

This study was conducted to investigate the effect of salt concentration and turbidity on the inactivation of Artemia sp. by electrolysis, UV photolysis, electrolysis+UV process to treat ballast water in the presence of brackish water or muddy water caused by rainfall. The inactivation at different salt concentrations (30 g/L and 3 g/L) and turbidity levels (0, 156, 779 NTU) was compared. A decrease in salt concentration reduced RNO (OH radical generation index) degradation and TRO (Total Residual Oxidant) production, indicating that a longer electrolysis time is required to achieve a 100% inactivation rate in electrolysis process. In the UV process, the higher turbidity results in lower UV transmittance and lower inactivation efficiency of Artemia sp. Higher the turbidity resulted in lower ultraviolet transmittance in the UV process and lower inactivation efficiency of Artemia sp. A UV exposure time of over 30 seconds was required for 100% inactivation. Factors affecting inactivation efficiency of Artemia sp. in low salt concentration are in the order: electrolysis+UV > electrolysis > UV process. In the case of electrolysis+UV process, TRO is lower than the electrolysis process, but RNO is more decomposed, indicating that the OH radical has a greater effect on the inactivation effect. In low salt concentrations and high turbidity conditions, factors affecting Artemia sp. inactivation were in the order electrolysis > electrolysis+UV > UV process. When the salt concentration is low and the turbidity is high, the electrolysis process is affected by the salt concentration and the UV process is affected by turbidity. Therefore, the synergy due to the combination of the electrolysis process and the UV process was small, and the inactivation was lower than that of the single electrolysis process only affected by the salt concentration.

휘발성유기화합물의 광분해 제거 특성에 관한 연구

서정민,정창훈 한국환경과학회 2002 한국환경과학회지 Vol.11 No.7

UV photolysis process is little known in parts of air pollution treatment, so there are not many applications in field. Therefore we have to do more experiment and study application possibility for treatment of VOCs(Volatile organic compounds). To solve these problems, we have been studying for simultaneous application of this technology. It has shown that concentration of TCE and B.T.X., diameter of reactor and wavelength of lamp have effected on decomposition efficiency. Analysis of TCE and B.T.X. concentration was carried out by GC-FID. A cylinderical reactor consisting of a quartz tube and a centrally located lamp(ψ25㎜) was used. The length and diameter of reactor were 1800㎜, 75㎜. It has shown that the generated ozone concentration goes up 250ppm when using 64watt ozone lamp. When using Photolysis process only, the rates of fractional conversion of each material are TCE 79%, Benzene 65%, Toluene 68%, Xylene 76%. This phenomenon can be rationalized in terms of the different bond energy that indicates how easily VOCs species can be decomposed.

Mechanim of UV photolysis and transport on the production of reactive oxygen and nitrogen species inside liquids exposed to atmospheric pressure plasma jet

Bhagirath Ghimire,Endre Szili,Pradeep Lamichhane,Eun Ha Choi 한국진공학회 2017 한국진공학회 학술발표회초록집 Vol.2017 No.8

광반응을 이용한 Triclosan 분해에서의 UV 광세기와 파장의 효과

손현석(Hyun Seok Son),최석봉(Seok Bong Choi),Eakalak Khan,조경덕(Kyung Duk Zoh) 大韓環境工學會 2005 대한환경공학회지 Vol.27 No.9

Degradation and fate of N-nitrosamines in water by UV photolysis

Afzal, A.,Kang, J.,Choi, B.M.,Lim, H.J. Elsevier BV 2016 INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL Vol.52 No.-

Carcinogenic nitrosamines have received much attention due to their formation in CO<SUB>2</SUB> capture processes and probable emission into the atmosphere. Fortunately, nitrosamines are decomposed by exposure to UV irradiation. This may be an effective strategy to degrade nitrosamines, forming more benign products in the process. In this work, UV photolysis was used to examine the degradation kinetics and fate of nitrosamines (i.e., N-nitrosodiethylamine (NDEA), N-nitrosodibutylamine (NDBA), N-nitrosodimethylamine (NDMA), N-nitrosodiethanolamine (NDELA), and N-nitrosopyrrolidine (NPYR)) in water at 40<SUP>o</SUP>C. Nearly all nitrosamines were decomposed within the first 10min of photodegradation using 4W, low pressure Hg lamp. Pseudo-first order reaction rate constants were 1.8x10<SUP>-2</SUP>, 2.6x10<SUP>-2</SUP>, 2.6x10<SUP>-2</SUP>, 2.3x10<SUP>-2</SUP>, and 1.4x10<SUP>-2</SUP>L/W-min for NDEA, NDBA, NDMA, NDELA, and NPYR, respectively. There was minimal change in total organic carbon (TOC) and total nitrogen (TN), suggesting negligible loss of nitrosamines and photodegradation products by evaporation.