title: Co-transport of gold nanospheres with single-walled carbon nanotubes in saturated porous media.
abstract: Porous media transport of engineered nanomaterials (ENMs) is typically assessed in a controlled single-particulate environment. Presence of a secondary particle (either natural or engineered) in the natural environment though likely, is rarely taken into consideration in assessing ENMs' transport behavior. This study systematically assesses the effect of a secondary ENM (i.e., pluronic acid modified single-walled carbon nanotubes, PA-SWNTs) on a primary particle (i.e., gold nanospheres, AuNSs) transport through saturated porous media under a wide range of aquatic conditions (1-100 mM NaCl). AuNS hetero-dispersions (i.e., with PA-SWNTs) are transported through saturated sand columns, and the transport behavior is compared to AuNS-only homo-dispersion cases, which display classical ionic strength-dependent behavior. AuNS hetero-dispersion, however, is highly mobile with little to no ionic strength-dependent effects. This study also assesses the role of pre-coating of the collectors with PA-SWNTs on AuNSs' mobility, thereby elucidating the role played by the order of introduction of the secondary particles. Pre-existence of the secondary particles in the porous media shows enhanced filtration of primary AuNSs. However, the presence of natural organic matter (NOM) slightly increases AuNS mobility through PA-SWNT coated sand at 10 mM ionic strength. The study results demonstrate that the presence and order of addition of the secondary particles strongly influence primary particles' mobility. Thus ENMs can demonstrate facilitated transport or enhanced removal, depending on the presence of the secondary particulate matter and background solution chemistry.
authors.affiliation: Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, TX 78712, United States.
authors.forename: A R M Nabiul
authors.initials: ARMN
authors.lastname: Afrooz
authors.affiliation: Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, TX 78712, United States.
authors.forename: Dipesh
authors.initials: D
authors.lastname: Das
authors.affiliation: Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States.
authors.forename: Catherine J
authors.initials: CJ
authors.lastname: Murphy
authors.affiliation: Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, United States.
authors.forename: Peter
authors.initials: P
authors.lastname: Vikesland
authors.affiliation: Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, TX 78712, United States. Electronic address: navid.saleh@utexas.edu.
authors.forename: Navid B
authors.initials: NB
authors.lastname: Saleh
mesh_terms: D006046:Gold; D054118:Nanospheres; D037742:Nanotubes, Carbon; D016062:Porosity; D027981:Symporters
chemical_list: D037742:Nanotubes, Carbon; D027981:Symporters; D006046:Gold
keywords: Co-transport; Gold nanoparticles; Pluronic; Porous media; Single-walled carbon nanotubes