title: Effect of humic acid on the sorption of perfluorooctane sulfonate (PFOS) and perfluorobutane sulfonate (PFBS) on boehmite.
abstract: The sorption of PFOS and PFBS on boehmite was significantly retarded by the competitive sorption of humic acid (HA), implying that PFOS and PFBS are likely more mobile in water and groundwater systems enriched with HA. The sorption behavior of PFOS and PFBS on the HA-modified boehmite surface were also found to differ due to their different chain lengths. For a partially HA-modified boehmite surface, the isotherm study showed that PFOS had a much higher maximum sorption capacity than PFBS and that PFOS might possess additional surface interactions besides electrostatic interaction. For a HA-saturated boehmite, a linear sorption isotherm was found for PFOS while nearly no PFBS sorption was observed. This indicates that sorption behavior between PFOS and the sorbed HA on boehmite was dominated by hydrophobic interactions, instead of electrostatic interaction. In addition, a conceptual model combining hydrophobic and electrostatic interaction was established to explain the sorption behavior of PFOS and PFBS on HA-modified boehmite. Finally, the results revealed that the sorption of PFOS and PFBS on HA-modified boehmite is pH-dependent. The neutralization of negative sites on HA-modified boehmite reduced the electrostatic repulsion and enhanced the partitioning of PFBS on the sorbed HA.
authors.affiliation: Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong.
authors.forename: Fei
authors.initials: F
authors.lastname: Wang
authors.affiliation: Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong. Electronic address: kshih@hku.hk.
authors.forename: Kaimin
authors.initials: K
authors.lastname: Shih
authors.affiliation: Department of Civil and Environmental Engineering, Stanford University, and Engineering Research Center for Re-inventing the Nation's Urban Water Infrastructure (ReNUWit), Stanford, CA 94305, USA.
authors.forename: James O
authors.initials: JO
authors.lastname: Leckie
mesh_terms: D000327:Adsorption; D017738:Alkanesulfonic Acids / Q000032:analysis*; D000536:Aluminum Hydroxide / Q000737:chemistry*; D000537:Aluminum Oxide / Q000737:chemistry*; D005466:Fluorocarbons / Q000032:analysis*; D060587:Groundwater / Q000032:analysis; D006812:Humic Substances / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D008956:Models, Chemical; D055672:Static Electricity; D013499:Surface Properties; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D017738:Alkanesulfonic Acids; D005466:Fluorocarbons; D006812:Humic Substances; D014874:Water Pollutants, Chemical; D000536:Aluminum Hydroxide; C069471:aluminum oxide hydroxide; C076994:perfluorooctane sulfonic acid; D000537:Aluminum Oxide; C108042:perfluorobutane
keywords: Electrostatic repulsion; Humic acid; Hydrophobic interaction; PFBS; PFOS