title: Photochemical behavior of carbon nanotubes in natural waters: reactive oxygen species production and effects on •OH generation by Suwannee River fulvic acid, nitrate, and Fe (III).
abstract: The photochemical activities of three kinds of carbon nanotubes (CNTs) were investigated in the present study. Efficient procedures of dispersing the three kinds of carbon nanotubes in water were established, and the quantitative analysis methods were also developed by TOC-absorbance method. High pH value or low ionic strength of the colloidal solutions facilitated the dispersion of CNTs. The suspensions of three kinds of CNTs could generate singlet oxygen ((1)O2) and hydroxyl radical (•OH) under irradiation of simulated sunlight, while superoxide radical (O2 (•-)) was not detected. The steady-state concentrations of (1)O2 and •OH generated by these CNTs were also determined. The presence of CNTs in natural waters can affect the photochemical behavior of water constituents, such as nitrate, dissolved organic matter, and Fe(3+). Specifically, in nitrate solution, the presence of CNTs could inhibit the generation of •OH by nitrate through light screening effect, while the quenching effect of hydroxyl radicals by CNTs was not observed. Besides light screening effect, the three kinds of CNTs used in the experiments also have a strong inhibiting effect on the ability of DOM to produce •OH by binding to the active sites. Moreover, the adsorption of Fe(3+) on MWCNT-OH and MWCNT-COOH could lead to its inactivation of formation of •OH in acidic conditions. However, the presence of the three kinds of CNTs did not affect the ligand-to-metal charge transfer (LMCT) reaction of DOM-Fe (III) complex.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, People's Republic of China.|Université Lyon 1, UMR CNRS 5256, Institut de Recherches sur la Catalyse et l'Environnement de Lyon (IRCELYON), 2 Avenue Albert Einstein, 69626, Villeurbanne, France.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection of the People's Republic of China, Nanjing, 210042, People's Republic of China.
authors.forename: Ya
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, People's Republic of China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Université Lyon 1, UMR CNRS 5256, Institut de Recherches sur la Catalyse et l'Environnement de Lyon (IRCELYON), 2 Avenue Albert Einstein, 69626, Villeurbanne, France.
authors.forename: Corinne
authors.initials: C
authors.lastname: Ferronato
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, People's Republic of China. yangxi@nju.edu.cn.
authors.forename: Xi
authors.initials: X
authors.lastname: Yang
authors.affiliation: Université Lyon 1, UMR CNRS 5256, Institut de Recherches sur la Catalyse et l'Environnement de Lyon (IRCELYON), 2 Avenue Albert Einstein, 69626, Villeurbanne, France. jean-marc.chovelon@ircelyon.univ-lyon1.fr.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Chovelon
mesh_terms: D001578:Benzopyrans / Q000737:chemistry*; D017665:Hydroxyl Radical / Q000737:chemistry; D008956:Models, Chemical; D037742:Nanotubes, Carbon / Q000032:analysis* / Q000737:chemistry; D009566:Nitrates; D009589:Nitrogen Oxides; D017382:Reactive Oxygen Species / Q000032:analysis* / Q000737:chemistry; D045483:Rivers / Q000737:chemistry; D026082:Singlet Oxygen / Q000737:chemistry; D012996:Solutions; D013472:Sunlight; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry
chemical_list: D001578:Benzopyrans; D037742:Nanotubes, Carbon; D009566:Nitrates; D009589:Nitrogen Oxides; D017382:Reactive Oxygen Species; D012996:Solutions; D014874:Water Pollutants, Chemical; D014867:Water; D026082:Singlet Oxygen; D017665:Hydroxyl Radical; C005023:fulvic acid
keywords: Carbon nanotubes; Dissolved organic matter; Iron ion; Nitrate; Photochemical behavior