Sorption of 14C-labeled multiwall carbon nanotubes by humic acid and polymers: Roles of sorbent properties

Published

March 8, 2016

Author(s)

Qing Zhao, Elijah Petersen, Xilong Wang, Xiaoying Guo, Shu Tao, Baoshan Xing

Abstract

Developing methods to measure interactions of carbon nanotubes (CNTs) with soils and sediments and understanding the relative strength of each sorbent property for CNTs sorption are essential for assessing CNTs environmental risks. In this study, we utilized carbon-14 labeled nanotubes to systematically investigated sorption of multiwall CNTs (MWCNTs) on 3 humic acids, 3 natural biopolymers, and 10 model polymers with a wide range of sorbent properties. Surface properties, rather than bulky properties of sorbents, greatly influenced MWCNTs sorption. A multiple linear model was successfully established to predict MWCNTs sorption on sorbents with different properties. Further, we examined direct and indirect effects of sorbent properties on MWCNT sorption via path analysis. Properties that were unfavorable for MWCNTs sorption were sorbent aromaticity, the difference in electrophoretic mobility between MWCNT and sorbents, ratio of micropore volumes to meso and macropore volumes, and dissolved organic matter released from sorbent. Conversely, surface polarity and surface area were favorable properties. Surface polarity was the most positive factor for sorption, indicating sorption was regulated by hydrogen bonding interactions. We also showed that MWCNTs are difficult to re-disperse once they have settled out of solution and/or have sorbed onto the sorbents. Our findings on the relative strength of sorbent properties for CNT sorption provide information for sorbent selection for removal of MWCNTs from wastewater and provide a method for measuring CNT interactions with organic sorbents.

Citation

Environmental Science & Technology

Pub Type

Journals

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Citation

Zhao, Q. , Petersen, E. , Wang, X. , Guo, X. , Tao, S. and Xing, B. (2016), Sorption of 14C-labeled multiwall carbon nanotubes by humic acid and polymers: Roles of sorbent properties, Environmental Science & Technology, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=916453 (Accessed October 8, 2024)