title: Compositional effects on leaching of stain-guarded (perfluoroalkyl and polyfluoroalkyl substance-treated) carpet in landfill leachate.
abstract: Perfluoroalkyl and polyfluoroalkyl substances (PFASs) from stain-guard treated carpets in landfills continue to be released into the environment. To understand the leaching of PFASs from carpets to landfill leachate as a function of environmental factors, leaching concentrations of ten perfluoroalkyl carboxylic acids and four perfluoroalkyl sulfonic acids were quantified for different pHs, contact times, mixing speeds, and temperatures. Partitioning from carpet to leachate and distilled water at different pHs showed negligible differences. The total concentration of leaching PFASs in distilled water was approximately 1 ng L(-1) higher than in landfill leachate, indicating that the presence of multivalent cations in leachate could have a negative effect on leaching of PFASs. For all PFASs monitored, leaching increased with increasing contact time and temperature. Perfluorohexanoic and perfluoroheptanoic acids experienced the largest increases with contact time and temperature. Gibbs free energy (ΔG > 0), enthalpy (ΔH > 0), and entropy energy (ΔS < 0) indicated that PFAS leaching from carpet was dominantly controlled by entropy-driven processes and did not differ significantly among individual PFASs. PFAS concentrations in leachate with rotation of an end-over-end contactor were higher than under static conditions, but otherwise, varying the rotation speed had negligible influence. The results provide useful information for management of discarded stain-guard carpets in landfills.
authors.affiliation: †Department of Civil Engineering, University of British Columbia, 6250 Applied Science Lane, Vancouver, British Columbia, Canada V6T 1Z4.
authors.forename: Minhee
authors.initials: M
authors.lastname: Kim
authors.affiliation: †Department of Civil Engineering, University of British Columbia, 6250 Applied Science Lane, Vancouver, British Columbia, Canada V6T 1Z4.
authors.forename: Loretta Y
authors.initials: LY
authors.lastname: Li
authors.affiliation: ‡Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, British Columbia, Canada V6T 1Z3.
authors.forename: John R
authors.initials: JR
authors.lastname: Grace
authors.affiliation: §Institute of Ocean Sciences, Fisheries and Oceans Canada (DFO), 9860 West Saanich Road, Sidney, British Columbia, Canada V8L 4B2.
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Benskin
authors.affiliation: §Institute of Ocean Sciences, Fisheries and Oceans Canada (DFO), 9860 West Saanich Road, Sidney, British Columbia, Canada V8L 4B2.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Ikonomou
mesh_terms: D002412:Cations; D005430:Floors and Floorcoverings; D005466:Fluorocarbons / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D012996:Solutions; D013696:Temperature; D013997:Time Factors; D064091:Waste Disposal Facilities; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D002412:Cations; D005466:Fluorocarbons; D012996:Solutions; D014874:Water Pollutants, Chemical