Molecular dynamics simulations of structural transformation of perfluorooctane sulfonate (PFOS) at water/rutile interfaces

He, G, Zhang, M, Zhou, Q and Pan, G ORCID: https://orcid.org/0000-0003-0920-3018, 2015. Molecular dynamics simulations of structural transformation of perfluorooctane sulfonate (PFOS) at water/rutile interfaces. Chemosphere, 134, pp. 272-278. ISSN 0045-6535

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Abstract

Concentration and salinity conditions are the dominant environmental factors affecting the behavior of perfluorinated compounds (PFCs) on the surfaces of a variety of solid matrices (suspended particles, sediments, and natural minerals). However, the mechanism has not yet been examined at molecular scales. Here, the structural transformation of perfluorooctane sulfonate (PFOS) at water/rutile interfaces induced by changes of the concentration level of PFOS and salt condition was investigated using molecular dynamics (MD) simulations. At low and intermediate concentrations all PFOS molecules directly interacted with the rutile (110) surface mainly by the sulfonate headgroups through electrostatic attraction, yielding a typical monolayer structure. As the concentration of PFOS increased, the molecules aggregated in a complex multi-layered structure, where an irregular assembling configuration was adsorbed on the monolayer structure by the van der Waals interactions between the perfluoroalkyl chains. When adding CaCl2 to the system, the multi-layered structure changed to a monolayer again, indicating that the addition of CaCl2 enhanced the critical concentration value to yield PFOS multilayer assemblies. The divalent Ca2+ substituted for monovalent K+ as the bridging counterion in PFOS adsorption. MD simulation may trigger wide applications in study of perfluorinated compounds (PFCs) from atomic/molecular scale.

Item Type:	Journal article
Publication Title:	Chemosphere
Creators:	He, G., Zhang, M., Zhou, Q. and Pan, G.
Publisher:	Pergamon Press
Date:	September 2015
Volume:	134
ISSN:	0045-6535
Identifiers:	Number Type 10.1016/j.chemosphere.2015.04.056 DOI
Divisions:	Schools > School of Architecture, Design and the Built Environment
Record created by:	Jonathan Gallacher
Date Added:	13 Jun 2016 08:45
Last Modified:	09 Jun 2017 14:03
URI:	https://irep.ntu.ac.uk/id/eprint/27962

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