title: Adsorbed poly(aspartate) coating limits the adverse effects of dissolved groundwater solutes on Fe0nanoparticle reactivity with trichloroethylene.
abstract: For in situ groundwater remediation, polyelectrolyte-modified nanoscale zerovalent iron particles (NZVIs) have to be delivered into the subsurface, where they degrade pollutants such as trichloroethylene (TCE). The effect of groundwater organic and ionic solutes on TCE dechlorination using polyelectrolyte-modified NZVIs is unexplored, but is required for an effective remediation design. This study evaluates the TCE dechlorination rate and reaction by-products using poly(aspartate) (PAP)-modified and bare NZVIs in groundwater samples from actual TCE-contaminated sites in Florida, South Carolina, and Michigan. The effects of groundwater solutes on short- and intermediate-term dechlorination rates were evaluated. An adsorbed PAP layer on the NZVIs appeared to limit the adverse effect of groundwater solutes on the TCE dechlorination rate in the first TCE dechlorination cycle (short-term effect). Presumably, the pre-adsorption of PAP "trains" and the Donnan potential in the adsorbed PAP layer prevented groundwater solutes from further blocking NZVI reactive sites, which appeared to substantially decrease the TCE dechlorination rate of bare NZVIs. In the second and third TCE dechlorination cycles (intermediate-term effect), TCE dechlorination rates using PAP-modified NZVIs increased substantially (~100 and 200%, respectively, from the rate of the first spike). The desorption of PAP from the surface of NZVIs over time due to salt-induced desorption is hypothesized to restore NZVI reactivity with TCE. This study suggests that NZVI surface modification with small, charged macromolecules, such as PAP, helps to restore NZVI reactivity due to gradual PAP desorption in groundwater.
authors.affiliation: Research Unit for Integrated Natural Resources Remediation and Reclamation (IN3R), Department of Civil Engineering, Faculty of Engineering, Naresuan University, Phitsanulok, 65000, Thailand. pomphenrat@gmail.com.|Center of Excellence for Sustainability of Health, Environment and Industry (SHEI), Faculty of Engineering, Naresuan University, Phitsanulok, 65000, Thailand. pomphenrat@gmail.com.
authors.forename: Tanapon
authors.identifier: http://orcid.org/0000-0003-2179-042X
authors.initials: T
authors.lastname: Phenrat
authors.affiliation: Center for Environmental Implications of Nanotechnology (CEINT) and Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, PA, 15213-3890, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Schoenfelder
authors.affiliation: Center for Environmental Implications of Nanotechnology (CEINT) and Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, PA, 15213-3890, USA.|Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA, 15213-3890, USA.|Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA, 15213-3890, USA.
authors.forename: Teresa L
authors.initials: TL
authors.lastname: Kirschling
authors.affiliation: Center for Environmental Implications of Nanotechnology (CEINT) and Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, PA, 15213-3890, USA.|Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA, 15213-3890, USA.|Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA, 15213-3890, USA.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Tilton
authors.affiliation: Center for Environmental Implications of Nanotechnology (CEINT) and Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, PA, 15213-3890, USA. glowry@cmu.edu.|Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA, 15213-3890, USA. glowry@cmu.edu.|Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA, 15213-3890, USA. glowry@cmu.edu.
authors.forename: Gregory V
authors.initials: GV
authors.lastname: Lowry
mesh_terms: D000327:Adsorption; D001224:Aspartic Acid / Q000737:chemistry*; D060587:Groundwater / Q000737:chemistry*; D054879:Halogenation; D007501:Iron / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D014241:Trichloroethylene / Q000737:chemistry* / Q000302:isolation & purification; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000302:isolation & purification; D018508:Water Purification / Q000379:methods*
chemical_list: D014874:Water Pollutants, Chemical; D014241:Trichloroethylene; D001224:Aspartic Acid; D007501:Iron
keywords: Chlorinated organics; Dechlorination kinetics; Desorption; Groundwater; Nanoscale zerovalent iron (NZVI); Poly(aspartate); Polyelectrolyte; Remediation