title: Sorption of perfluoroalkyl substances in sewage sludge.
abstract: The sorption behaviour of three perfluoroalkyl substances (PFASs) (perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and perfluorobutanesulfonic acid (PFBS)) was studied in sewage sludge samples. Sorption isotherms were obtained by varying initial concentrations of PFOS, PFOA and PFBS. The maximum values of the sorption solid-liquid distribution coefficients (Kd,max) varied by almost two orders of magnitude among the target PFASs: 140-281 mL g(-1) for PFOS, 30-54 mL g(-1) for PFOA and 9-18 mL g(-1) for PFBS. Freundlich and linear fittings were appropriate for describing the sorption behaviour of PFASs in the sludge samples, and the derived KF and Kd,linear parameters correlated well. The hydrophobicity of the PFASs was the key parameter that influenced their sorption in sewage sludge. Sorption parameters and log(KOW) were correlated, and for PFOS (the most hydrophobic compound), pH and Ca + Mg status of the sludge controlled the variation in the sorption parameter values. Sorption reversibility was also tested from desorption isotherms, which were also linear. Desorption parameters were systematically higher than the corresponding sorption parameters (up to sixfold higher), thus indicating a significant degree of irreversible sorption, which decreased in the sequence PFOS > PFOA > PFBS.
authors.affiliation: Department of Analytical Chemistry, University of Barcelona, Martí i Franquès 1-11, 08028, Barcelona, Spain.
authors.forename: Jelena
authors.initials: J
authors.lastname: Milinovic
authors.affiliation: Department of Environmental Chemistry, IDAEA-CSIC, Jordi Girona 18-26, 08034, Barcelona, Spain.
authors.forename: Silvia
authors.initials: S
authors.lastname: Lacorte
authors.affiliation: Department of Analytical Chemistry, University of Barcelona, Martí i Franquès 1-11, 08028, Barcelona, Spain. annarigol@ub.edu.
authors.forename: Anna
authors.initials: A
authors.lastname: Rigol
authors.affiliation: Department of Analytical Chemistry, University of Barcelona, Martí i Franquès 1-11, 08028, Barcelona, Spain.
authors.forename: Miquel
authors.initials: M
authors.lastname: Vidal
mesh_terms: D065966:Absorption, Physicochemical; D017738:Alkanesulfonic Acids / Q000737:chemistry; D002210:Caprylates / Q000737:chemistry; D005466:Fluorocarbons / Q000032:analysis / Q000737:chemistry*; D012722:Sewage / Q000737:chemistry*; D013451:Sulfonic Acids / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*
chemical_list: D017738:Alkanesulfonic Acids; D002210:Caprylates; D005466:Fluorocarbons; D012722:Sewage; D013451:Sulfonic Acids; D014874:Water Pollutants, Chemical; C539348:perfluorobutanesulfonic acid; C023036:perfluorooctanoic acid; C076994:perfluorooctane sulfonic acid
keywords: Desorption; Perfluorobutanesulfonic acid; Perfluorooctanesulfonic acid; Perfluorooctanoic acid; Sewage sludge; Sorption