Please use this identifier to cite or link to this item: https://hdl.handle.net/11499/28219
Title: Role of microbial exopolymeric substances (EPS) on chromium sorption and transport in heterogeneous subsurface soils: I. Cr(III) complexation with EPS in aqueous solution
Authors: Kantar, Çetin
Demiray, Hilal
Mercan Doğan, Nazime
J. Dodge, Cleveland
Keywords: Chromium
Discrete ligand model
Complexation
EPS
Speciation
Transport
Publisher: PERGAMON-ELSEVIER SCIENCE LTD, THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND
Abstract: Chromium (III) binding by exopolymeric substances (EPS) isolated from Pseudomonas putida P18, Pseudomonas aeruginosa P16 and Pseudomonas stutzeri P40 strains were investigated by the determination of conditional stability constants and the concentration of functional groups using the ion-exchange experiments and potentiometric titrations. Spectroscopic (EXAFS) analysis was also used to obtain information on the nature of Cr(III) binding with EPS functional groups. The data from ion-exchange experiments and potentiometric titrations were evaluated using a non-electrostatic discrete ligand approach. The modeling results show that the acid/base properties of EPSs can be best characterized by invoking four different types of acid functional groups with arbitrarily assigned pKa values of 4, 6, 8 and 10. The analysis of ion-exchange data using the discrete ligand approach suggests that while the Cr binding by EPS from P. aeruginosa can be successfully described based on a reaction stoichiometry of 1:2 between Cr(III) and HL2 monoprotic ligands, the accurate description of Cr binding by EPSs extracted from P. putida and P. stutzeri requires postulation of 1:1 Cr(III)-ligand complexes with HL2 and HL3 monoprotic ligands, respectively. These results indicate that the carboxyl and/or phosphoric acid sites contribute to Cr(III) binding by microbial EPS, as also confirmed by EXAFS analysis performed in the current study. Overall, this study highlights the need for incorporation of Cr–EPS interactions into transport and speciation models to more accurately assess microbial Cr(VI) reduction and chromium transport in subsurface systems, including microbial reactive treatment barriers.
URI: https://hdl.handle.net/11499/28219
ISSN: 0045-6535
Appears in Collections:Fen-Edebiyat Fakültesi Koleksiyonu
PubMed İndeksli Yayınlar Koleksiyonu / PubMed Indexed Publications Collection
Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

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