title: Kinetics of Brominated Flame Retardant (BFR) Releases from Granules of Waste Plastics.
abstract: Plastic components of e-waste contain high levels of brominated flame retardants (BFRs), whose releases cause environmental and human health concerns. This study characterized the release kinetics of polybrominated diphenyl ethers (PBDEs) from millimeter-sized granules processed from the plastic exteriors of two scrap computer displays at environmentally relevant temperatures. The release rate of a substitute of PBDEs, 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), from the waste plastics, was reported for the first time. Deca-BDE was the most abundant PBDE congeners in both materials (87-89%), while BTBPE was also present at relatively high contents. The release kinetics of BFRs could be modeled as one-dimensional diffusion, while the temperature dependence of diffusion coefficients was well described by the Arrhenius equation. The diffusion coefficients of BFRs (at 30 °C) in the plastic matrices were estimated to be in the range of 10-27.16to 10-19.96m2·s-1, with apparent activation energies between 88.4 and 154.2 kJ·mol-1. The half-lives of BFR releases (i.e., 50% depletion) from the plastic granules ranged from thousands to tens of billions of years at ambient temperatures. These findings suggest that BFRs are released very slowly from the matrices of waste plastics through molecular diffusion, while their emissions can be significantly enhanced with wear-and-tear and pulverization.
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences , Guangzhou 510640, China.|University of Chinese Academy of Sciences , Beijing 100049, China.
authors.forename: Bingbing
authors.initials: B
authors.lastname: Sun
authors.affiliation: MOE Laboratory of Groundwater Circulation and Evolution, School of Water Resources and Environment, China University of Geosciences (Beijing) , Beijing 100083, China.
authors.forename: Yuanan
authors.initials: Y
authors.lastname: Hu
authors.affiliation: MOE Key Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University , Beijing 100871, China.
authors.forename: Hefa
authors.identifier: 0000-0003-4911-6971
authors.initials: H
authors.lastname: Cheng
authors.affiliation: MOE Key Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University , Beijing 100871, China.
authors.forename: Shu
authors.identifier: 0000-0002-7374-7063
authors.initials: S
authors.lastname: Tao
mesh_terms: D004784:Environmental Monitoring; D005411:Flame Retardants; D055768:Halogenated Diphenyl Ethers; D006842:Hydrocarbons, Brominated; D007700:Kinetics; D010969:Plastics
chemical_list: D005411:Flame Retardants; D055768:Halogenated Diphenyl Ethers; D006842:Hydrocarbons, Brominated; D010969:Plastics