title: Degradation of (14)C-labeled few layer graphene via Fenton reaction: Reaction rates, characterization of reaction products, and potential ecological effects.
abstract: Graphene has attracted considerable commercial interest due to its numerous potential applications. It is inevitable that graphene will be released into the environment during the production and usage of graphene-enabled consumer products, but the potential transformations of graphene in the environment are not well understood. In this study, (14)C-labeled few layer graphene (FLG) enabled quantitative measurements of FLG degradation rates induced by the iron/hydrogen peroxide induced Fenton reaction. Quantification of (14)CO2 production from (14)C-labeled FLG revealed significant degradation of FLG after 3 days with high H2O2 (200 mmol L(-1)) and iron (100 μmol L(-1)) concentrations but substantially lower rates under environmentally relevant conditions (0.2-20 mmol L(-1) H2O2 and 4 μmol L(-1) Fe(3+)). Importantly, the carbon-14 labeling technique allowed for quantification of the FLG degradation rate at concentrations nearly four orders of magnitude lower than those typically used in other studies. These measurements revealed substantially faster degradation rates at lower FLG concentrations and thus studies with higher FLG concentrations may underestimate the degradation rates. Analysis of structural changes to FLG using multiple orthogonal methods revealed significant FLG oxidation and multiple reaction byproducts. Lastly, assessment of accumulation of the degraded FLG and intermediates using aquatic organism Daphnia magna revealed substantially decreased body burdens, which implied that the changes to FLG caused by the Fenton reaction may dramatically impact its potential ecological effects.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023, China.
authors.forename: Yiping
authors.initials: Y
authors.lastname: Feng
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Lu
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023, China. Electronic address: lmao@nju.edu.cn.
authors.forename: Liang
authors.initials: L
authors.lastname: Mao
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023, China.
authors.forename: Xiangke
authors.initials: X
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023, China.
authors.forename: Shixiang
authors.initials: S
authors.lastname: Gao
authors.affiliation: Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
authors.forename: Elijah J
authors.initials: EJ
authors.lastname: Petersen
mesh_terms: D002250:Carbon Radioisotopes / Q000737:chemistry*; D004463:Ecology; D006108:Graphite / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry*
chemical_list: D002250:Carbon Radioisotopes; D006108:Graphite; D006861:Hydrogen Peroxide
keywords: (14)C-labeled few layer graphene; (14)CO(2) generation; Characterizations; Degradation kinetics; Fenton reaction; Quantification