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Wang J, Huang D, Chen F, Chen J, Jiang H, Zhu Y, Chen C, Zhao J. Rapid Redox Cycling of Fe(II)/Fe(III) in Microdroplets during Iron-Citric Acid Photochemistry. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:4434-4442. [PMID: 36883325 DOI: 10.1021/acs.est.2c07897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Fe(III) and carboxylic acids are common compositions in atmospheric microdroplet systems like clouds, fogs, and aerosols. Although photochemical processes of Fe(III)-carboxylate complexes have been extensively studied in bulk aqueous solution, relevant information on the dynamic microdroplet system, which may be largely different from the bulk phase, is rare. With the help of the custom-made ultrasonic-based dynamic microdroplet photochemical system, this study examines the photochemical process of Fe(III)-citric acid complexes in microdroplets for the first time. We find that when the degradation extent of citric acid is similar between the microdroplet system and the bulk solution, the significantly lower Fe(II) ratio is present in microdroplet samples due to the rapider reoxidation of photogenerated Fe(II). However, by replacing citric acid with benzoic acid, no much difference in the Fe(II) ratio between microdroplets and bulk solution is observed, which indicates distinct reoxidation pathways of Fe(II). Moreover, the presence of •OH scavenger, namely, methanol, greatly accelerates the reoxidation of photogenerated Fe(II) in both citric acid and benzoic acid situations. Further experiments reveal that the high availability of O2 and the citric acid- or methanol-derived carbon-centered radicals are responsible for the rapider reoxidation of Fe(II) in iron-citric acid microdroplets by prolonging the length of HO2•- and H2O2-involved radical reaction chains. The results in this study may provide a new understanding about iron-citric acid photochemistry in atmospheric liquid particles, which can further influence the photoactivity of particles and the formation of secondary organic aerosols.
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Affiliation(s)
- Jinzhao Wang
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Di Huang
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Fengxia Chen
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Jianhua Chen
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Hongyu Jiang
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Yifan Zhu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Chuncheng Chen
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Jincai Zhao
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
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Zhou Y, West CP, Hettiyadura APS, Pu W, Shi T, Niu X, Wen H, Cui J, Wang X, Laskin A. Molecular Characterization of Water-Soluble Brown Carbon Chromophores in Snowpack from Northern Xinjiang, China. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:4173-4186. [PMID: 35287433 DOI: 10.1021/acs.est.1c07972] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
This study reports molecular-level characterization of brown carbon (BrC) attributed to water-soluble organic carbon in six snowpack samples collected from northern Xinjiang, China. The molecular composition and light-absorbing properties of BrC chromophores were unraveled by application of high-performance liquid chromatography (HPLC) coupled to a photodiode array (PDA) detector and high-resolution mass spectrometry. The chromophores were classified into five major types, that is, (1) phenolic/lignin-derivedcompounds, (2) flavonoids, (3) nitroaromatics, (4) oxygenated aromatics, and (5) other chromophores. Identified chromophores account for ∼23-64% of the total light absorption measured by the PDA detector in the wavelength range of 300-370 nm. In the representative samples from urban and remote areas, oxygenated aromatics and nitroaromatics dominate the absorption in the wavelengths below and above 320 nm, respectively. The highly polluted urban sample shows the most complex HPLC-PDA chromatogram, and more other chromophores contribute to the bulk absorption. Phenolic/lignin-derived compounds are the most light-absorbing species in the soil-influenced sample. Chromophores in two remote samples exhibit ultraviolet-visible features distinct from other samples, which are attributed to flavonoids. Identification of individual chromophores and quantitative analysis of their optical properties are helpful for elucidating the roles of BrC in snow radiative balance and photochemistry.
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Affiliation(s)
- Yue Zhou
- Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Christopher P West
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Anusha P S Hettiyadura
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Wei Pu
- Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
| | - Tenglong Shi
- Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
| | - Xiaoying Niu
- Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
| | - Hui Wen
- Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
| | - Jiecan Cui
- Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
| | - Xin Wang
- Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
- Institute of Surface-Earth System Science, Tianjin University, Tianjin 300072, China
| | - Alexander Laskin
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
- Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, Indiana 47907, United States
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Ferreira MPS, Santos PSM, Duarte AC. Oxidation of small aromatic compounds in rainwater by UV/H 2O 2: Optimization by response surface methodology. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 815:152857. [PMID: 34995602 DOI: 10.1016/j.scitotenv.2021.152857] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 12/28/2021] [Accepted: 12/29/2021] [Indexed: 06/14/2023]
Abstract
The presence of aromatic compounds in rainwater is a matter of concern, mainly when the use of rainwater in buildings is intended. The present work aimed to assess the oxidation of a mixture of small aromatic compounds (benzoic, 3,5-dihydroxybenzoic and syringic acids) in rainwater by the UV/H2O2 process, and the possibility of its optimization by the response surface methodology. The extent of oxidation was assessed by ultraviolet-visible and molecular fluorescence spectroscopies. During the oxidation of the mixture new chromophoric compounds were formed at an initial stage, but they were then degraded at a later stage. The increase of the H2O2 concentration, resulted in a higher extent of oxidation, while the initial pH value showed no influence in the oxidation of the mixture. The optimization of the oxidation was performed using the uniform design with the factors: initial H2O2 concentration, initial pH, and reaction time. The response surface model found, through the best subsets regression, described the extent of oxidation as function of the following variables: initial H2O2 concentration and reaction time, interaction between them, and also their respective quadratic forms. The optimal conditions, the lowest H2O2 concentration (3.1 mM) for a selected maximum reaction time (4 h), were applied to rainwater samples spiked with the mixture of contaminants and resulted in an extent of oxidation higher than 99.5%, validating the application of the model to real samples. Therefore, the UV/H2O2 process coupled to its optimization via response surface methodology may be an alternative for rainwater treatment in buildings.
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Affiliation(s)
- Mónica P S Ferreira
- CESAM & Department of Chemistry, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
| | - Patrícia S M Santos
- CESAM & Department of Chemistry, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
| | - Armando C Duarte
- CESAM & Department of Chemistry, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
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Yang C, Zhang C, Luo X, Liu X, Cao F, Zhang YL. Isomerization and Degradation of Levoglucosan via the Photo-Fenton Process: Insights from Aqueous-Phase Experiments and Atmospheric Particulate Matter. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:11789-11797. [PMID: 32897062 DOI: 10.1021/acs.est.0c02499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
So far, studies on the conversion of stereochemistry under photo-Fenton conditions and their atmospheric implication are still rare. Here, we found that the biomass burning marker, the chiral compound levoglucosan (L), undergoes oxidative degradation under photo-Fenton conditions and can be isomerized into mannosan (M) and galactosan (G) simultaneously. Among the formic acid, acetic acid, and oxalic acid in the degradation products of levoglucosan, it was found that the yield of formation of formic acid in the photo-Fenton pathway can be as high as 86%. It is worth noting that both levoglucosan and its isomers are present in the atmosphere and their concentrations are strongly correlated. At the same time, the range of their concentration ratios, L/(G + M), measured in the photo-Fenton experiments in the laboratory was found to agree well with that measured in atmospheric PM2.5 samples. However, the sources of L, G, and M in the atmosphere are complex, and the photo-Fenton reaction may be an essential pathway for the distribution of L, G, and M in the atmosphere.
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Affiliation(s)
- Chi Yang
- School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China
| | - Chunyan Zhang
- School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China
| | - Xiaosan Luo
- School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China
| | - Xiaoyan Liu
- School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China
| | - Fang Cao
- School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China
| | - Yan-Lin Zhang
- School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China
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Harrison AW, Shaw MF, De Bruyn WJ. Theoretical Investigation of the Atmospheric Photochemistry of Glyoxylic Acid in the Gas Phase. J Phys Chem A 2019; 123:8109-8121. [DOI: 10.1021/acs.jpca.9b06268] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Aaron W. Harrison
- Schmid College of Science and Technology, Chapman University, Orange, California 98266, United States
| | - Miranda F. Shaw
- School of Chemistry, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Warren J. De Bruyn
- Schmid College of Science and Technology, Chapman University, Orange, California 98266, United States
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