Sorption of PFOS isomers on goethite as a function of pH, dissolved organic matter (humic and fulvic acid) and sulfate. (October 2019)

• Record Type: Journal Article
• Authors: Uwayezu, Jean-Noel; Yeung, Leo W.Y.; Bäckström, Mattias
• Is Part Of: Chemosphere. Volume 233(2019)
• Page Start: 896
• Page End: 904
• Publication Date: 2019-10
• Subjects: Goethite -- Perfluorooctane sulfonate -- Sorption -- Humic substances -- Electrostatic and hydrophobic interactions; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2019.05.252
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Understanding the distribution of PFOS isomers between the aqueous phase and goethite is crucial, since it is an abundant sorbent and thus may have a large influence on the mobility of PFOS. This study was conducted to understand the effects of pH, humic acid (HA), fulvic acid (FA) and sulfate on sorption of PFOS isomers. The results will increase the understanding about what parameters may control the fate and transport of PFOS in surface and ground water. The study was conducted by adding PFOS spiked water to a goethite slurry with different aqueous chemistry. Levels of total PFOS and PFOS isomers were quantified using an Ultra-Performance Liquid Chromatograph coupled to a triple quadrupole mass spectrometer. Results showed that sorption of PFOS was mainly dependent on pH; sorption decreased as pH increased. Presence of HA increased log Kd from 1.29 to 2.03, 1.76 to 1.92 and 1.51 to 1.96 at pH 5.50–7.50 for 3-/4-/4-PFOS, 6-/2-PFOS and L-PFOS, respectively. Changes in the aqueous chemistry also affected the behaviour of PFOS as the addition of Na2 SO4 enhanced the sorption of PFOS. Results showed that L-PFOS was more readily sorbed to goethite at pH < 4.35 both in the presence and in the absence of humic or fulvic acids. At pH > 4.5 the 3-/4-/5-PFOS isomer group was more associated to goethite. Besides electrostatic interactions, which controlled the sorption of PFOS, this study indicate that the presence of dissolved humic substances in the aqueous phase enhances the sorption via hydrophobic mechanisms. Highlights: Sorption of PFOS isomers to goethite was mainly depending on pH; sorption was controlled by electrostatic mechanisms. Presence of HA or FA enhanced sorption to goethite both via hydrophobic and electrostatic mechanisms. L-PFOS was more readily sorbed to goethite at pH < 4.35, both in the presence and in the absence of humic substances. At a pH above 4.5 the 3-/4-/5-PFOS isomer group was more sorbed to the solid phase compared to the other isomers.