title: Retention of 14C-labeled multiwall carbon nanotubes by humic acid and polymers: Roles of macromolecule properties.
abstract: Developing methods to measure interactions of carbon nanotubes (CNTs) with soils and sediments and understanding the impact of soil and sediment properties on CNT deposition are essential for assessing CNT environmental risks. In this study, we utilized functionalized carbon-14 labeled nanotubes to systematically investigate retention of multiwall CNTs (MWCNTs) by 3 humic acids, 3 natural biopolymers, and 10 model solid-phase polymers, collectively termed macromolecules. Surface properties, rather than bulk properties of macromolecules, greatly influenced MWCNT retention. As shown via multiple linear regression analysis and path analysis, aromaticity and surface polarity were the two most positive factors for retention, suggesting retention was regulated by π-π stacking and hydrogen bonding interactions. Moreover, MWCNT deposition was irreversible. These observations may explain the high retention of MWCNT in natural soils. Moreover, our findings on the relative contribution of each macromolecule property on CNT retention provide information on macromolecule selection for removal of MWCNTs from wastewater and provide a method for measuring CNT interactions with organic macromolecules.
authors.affiliation: Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China; Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, USA; Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhao
authors.affiliation: Biosystems and Biomaterials Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
authors.forename: Elijah J
authors.initials: EJ
authors.lastname: Petersen
authors.affiliation: Department of chemistry and Molecular Biology, University of Gothenburg, Gothenburg 41296, Sweden.
authors.forename: Geert
authors.initials: G
authors.lastname: Cornelis
authors.affiliation: Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
authors.forename: Xilong
authors.initials: X
authors.lastname: Wang
authors.affiliation: Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Guo
authors.affiliation: Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
authors.forename: Shu
authors.initials: S
authors.lastname: Tao
authors.affiliation: Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, USA.
authors.forename: Baoshan
authors.initials: B
authors.lastname: Xing