Publication:
Superoxide-mediated reduction of organically complexed iron(III): Impact of pH and competing cations (Ca2+)

dc.contributor.author Garg, Shikha en_US
dc.contributor.author Rose, Andrew en_US
dc.contributor.author Waite, T en_US
dc.date.accessioned 2021-11-25T14:14:38Z
dc.date.available 2021-11-25T14:14:38Z
dc.date.issued 2007 en_US
dc.description.abstract The mechanism and kinetics of superoxide-mediated reduction of a variety of organic iron(III) complexes has been investigated over the pH range 7-9. Our experimental results show that the rate of iron(II) formation is a function of pH, ligand type and ligand concentration with the measured rate varying between 0.44 ± 0.07 and 39.25 ± 1.77 pM s-1 in the systems investigated. Additionally, our results show that the presence of competing cations such as Ca2+ have a significant impact on iron(II) formation if the organic ligand is strongly complexed by Ca2+. Formation of iron(II) occurs by either (or, in some instances, both) reaction of superoxide with inorganic iron(III) after its dissociation from the complex (dissociative reduction) or by direct reaction of superoxide with the complex (non-dissociative reduction). In the presence of weak ligands, dissociative reduction (DR) dominates; however non-dissociative reduction (NDR) becomes important in the presence of either strongly binding ligands or high concentrations of weakly binding ligands. The major factors contributing to the pH dependence of the iron(II) formation rate are the complexation kinetics of inorganic iron(III) (which controls the DR contribution) and the reduction kinetics of the iron(III) complex (which controls the NDR contribution). The relative NDR contribution increases with increasing superoxide and ligand concentration and decreasing pH for all ligands examined. Since iron(II) formation occurring via NDR results in a significantly larger increase in the proportion of iron in free aquated form than does DR, this non-dissociative pathway of superoxide-mediated iron(III) reduction is particularly effective in increasing the lability of iron in aquatic systems. © 2007 Elsevier Ltd. All rights reserved. en_US
dc.identifier.issn 0016-7037 en_US
dc.identifier.uri http://hdl.handle.net/1959.4/42283
dc.language English
dc.language.iso EN en_US
dc.rights CC BY-NC-ND 3.0 en_US
dc.rights.uri https://creativecommons.org/licenses/by-nc-nd/3.0/au/ en_US
dc.source Legacy MARC en_US
dc.subject.other Cation en_US
dc.subject.other Complexation en_US
dc.subject.other Iron en_US
dc.subject.other Ligand en_US
dc.subject.other Ligand en_US
dc.title Superoxide-mediated reduction of organically complexed iron(III): Impact of pH and competing cations (Ca2+) en_US
dc.type Journal Article en
dcterms.accessRights metadata only access
dspace.entity.type Publication en_US
unsw.accessRights.uri http://purl.org/coar/access_right/c_14cb
unsw.relation.faculty Engineering
unsw.relation.ispartofissue 23 en_US
unsw.relation.ispartofjournal Geochimica et Cosmochimica ACTA en_US
unsw.relation.ispartofpagefrompageto 5620-5634 en_US
unsw.relation.ispartofvolume 71 en_US
unsw.relation.originalPublicationAffiliation Garg, Shikha, Civil & Environmental Engineering, Faculty of Engineering, UNSW en_US
unsw.relation.originalPublicationAffiliation Rose, Andrew, Civil & Environmental Engineering, Faculty of Engineering, UNSW en_US
unsw.relation.originalPublicationAffiliation Waite, T, Civil & Environmental Engineering, Faculty of Engineering, UNSW en_US
unsw.relation.school School of Civil and Environmental Engineering *
Files
Resource type