Strong binding of apolar hydrophobic organic contaminants by dissolved black carbon released from biochar: A mechanism of pseudomicelle partition and environmental implications. (January 2018)

• Record Type: Journal Article
• Authors: Fu, Heyun; Wei, Chenhui; Qu, Xiaolei; Li, Hui; Zhu, Dongqiang
• Is Part Of: Environmental pollution. Volume 232(2018)
• Page Start: 402
• Page End: 410
• Publication Date: 2018-01
• Subjects: Dissolved black carbon -- Hydrophobic organic contaminants -- Pseudomicellar structures -- Hydrophobic partition; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2017.09.053
• Languages: English
• ISSNs: 0269-7491

Abstract

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. Graphical abstract: Highlights: Dissolved black carbon (DBC) can strongly bind hydrophobic organic contaminants. DBC effectively enhanced the apparent water solubility of tested contaminants. Binding of hydrophobic contaminants to DBC was dominated by hydrophobic partition. The binding interaction was favored by the pseudomicellar conformation of DBC. Abstract : Dissolved black carbon is a very effective component in dissolved organic matter to bind hydrophobic organic contaminants.