title: Sorption of short- and long-chain perfluoroalkyl surfactants on sewage sludges.
abstract: Perfluoroalkyl surfactants (PASs) have attracted increasing concerns in recent years due to their global distribution, persistence, bioaccumulation and potential toxicity. Since sludge was a significant source of PASs to environment, the sorption of short (C2-C6) and long-chain (C7-C15) PASs on different sewage sludge was investigated in this study. The equilibrium data were well represented by the Freundlich isotherm and were generally nonlinear. In order to elucidate the sorption mechanism of PASs to sludge, effect of sludge property, solution chemistry and molecular structure were also investigated in details. The dominant sludge parameter influencing sorption of PASs was protein in extracellular polymeric substances. The sorption of PASs onto sludge increased as solution pH decreased. For all the PASs homologues, enhanced adsorption occurred with increasing calcium concentration in solution. For PASs with C5-C15, sorption on sludge increases with increasing alkyl chain length, while for PASs with C2-C5, the association of sludge decreases when the alkyl chain length increases. The perfluorinated sulfonic acid (PFSA) demonstrated substantially stronger sorption than perfluorinated carboxylic acid (PFCA) analog. Evidence for both hydrophobic and electrostatic interactions was found.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China. myrazh@tongji.edu.cn
authors.forename: Chaojie
authors.initials: C
authors.lastname: Zhang
authors.forename: Hong
authors.initials: H
authors.lastname: Yan
authors.forename: Fei
authors.initials: F
authors.lastname: Li
authors.forename: Xiang
authors.initials: X
authors.lastname: Hu
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhou
mesh_terms: D000327:Adsorption; D002118:Calcium / Q000737:chemistry; D002241:Carbohydrates / Q000737:chemistry; D002244:Carbon / Q000737:chemistry; D002264:Carboxylic Acids / Q000737:chemistry; D002681:China; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D012722:Sewage; D012964:Sodium / Q000737:chemistry; D055672:Static Electricity; D013501:Surface-Active Agents / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry; D018508:Water Purification / Q000379:methods
chemical_list: D002118:Calcium; D002241:Carbohydrates; D002244:Carbon; D002264:Carboxylic Acids; D012722:Sewage; D012964:Sodium; D013501:Surface-Active Agents; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Electrostatic interactions; Hydrophobic interactions; Perfluoroalkyl surfactants; Sewage sludges; Sorption