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Strong binding of apolar hydrophobic organic contaminants by dissolved black carbon released from biochar: A mechanism of pseudomicelle partition and environmental implications.

Authors
  • Fu, Heyun1
  • Wei, Chenhui1
  • Qu, Xiaolei1
  • Li, Hui2
  • Zhu, Dongqiang3
  • 1 State Key Laboratory of Pollution Control and Resource Reuse/School of the Environment, Nanjing University, Jiangsu 210046, China. , (China)
  • 2 Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, United States. , (United States)
  • 3 State Key Laboratory of Pollution Control and Resource Reuse/School of the Environment, Nanjing University, Jiangsu 210046, China; School of Urban and Environmental Sciences, Peking University, Beijing 100871, China. Electronic address: [email protected] , (China)
Type
Published Article
Journal
Environmental pollution (Barking, Essex : 1987)
Publication Date
Jan 01, 2018
Volume
232
Pages
402–410
Identifiers
DOI: 10.1016/j.envpol.2017.09.053
PMID: 28966024
Source
Medline
Keywords
License
Unknown

Abstract

Dissolved black carbon (DBC), the soluble fraction of black carbon (BC), is an important constituent of dissolved organic matter pool. However, little is known about the binding interactions between hydrophobic organic contaminants (HOCs) and DBC and their significance in the fate process. This study determined the binding ability of DBC released from rice-derived BC for a series of apolar HOCs, including four polycyclic aromatic hydrocarbons and four chlorinated benzenes, using batch sorption and solubility enhancement techniques. Bulk BC and a dissolved soil humic acid (DSHA) were included as benchmark sorbents. The organic carbon-normalized sorption coefficient of phenanthrene to DBC was slightly lower than bulk BC, but was over ten folds higher than DSHA. Consistently, DBC was more effective than DSHA in enhancing the apparent water solubility of the tested HOCs, and the enhancement positively correlated with solute n-octanol-water partition coefficient, indicating the predominance of hydrophobic partition. The much higher binding ability of DBC relative to DSHA was mainly attributed to its higher tendency to form pseudomicellar structures as supported by the fluorescence quenching and the pH-edge data. Our findings suggest that DBC might play a significant role in the environmental fate and transport of HOCs as both sorbent and carrier.

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