Sorption of perfluoroalkyl substances to two types of minerals.
The sorption of perfluoroalkyl substances (PFASs) was investigated for two model soil mineral surfaces, alumina (Al2O3) and silica (SiO2), on molecular level using neutron scattering. The PFASs were selected (i.e. perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorooctane sulfonic acid (PFOS)) to examine the role of hydrophobic chain length and hydrophilic functional group on their sorption behaviour. All four PFASs were found to sorb to alumina surface (positively charged) forming a hydrated layer consisting of 50% PFASs. The PFAS solubility limit, which decrease with chain length, was found to strongly influence the sorption behaviour. The sorbed PFAS layer could easily be removed by gentle rinsing with water, indicating release upon rainfall in the environment. No sorption was observed for PFOA and PFOS at silica surface (negatively charged), showing electrostatic interaction being the driving force in the sorption process.
Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20, Uppsala, Sweden. Electronic address: maja.hellsing@physics.uu.se.
Maja S
MS
Hellsing
Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences (SLU), Box 7050, SE-750 07, Uppsala, Sweden.
Sarah
S
Josefsson
Rutherford Appleton Laboratory, Harwell Oxford, Didcot, OX11 0QX, United Kingdom.
Arwel V
AV
Hughes
Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences (SLU), Box 7050, SE-750 07, Uppsala, Sweden.
Lutz
L
Ahrens
D000327:Adsorption; D017738:Alkanesulfonic Acids / Q000737:chemistry*; D002208:Caproates / Q000737:chemistry*; D002210:Caprylates / Q000737:chemistry*; D005466:Fluorocarbons / Q000737:chemistry*; D008903:Minerals / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis
D017738:Alkanesulfonic Acids; D002208:Caproates; D002210:Caprylates; D005466:Fluorocarbons; D008903:Minerals; D014874:Water Pollutants, Chemical; D012822:Silicon Dioxide; C023036:perfluorooctanoic acid; C076994:perfluorooctane sulfonic acid; C479228:perfluorohexanoic acid
Alumina; Mineral; Neutron reflection; Perfluoroalkyl substances (PFASs); Silica; Sorption