Reduction of mercury(II) by tropical river humic substances (Rio Negro) - Part II. Influence of structural features (molecular size, aromaticity, phenolic groups, organically bound sulfur)

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dc.contributor.authorRocha, J. C.
dc.contributor.authorSargentini, E.
dc.contributor.authorZara, L. F.
dc.contributor.authorRosa, André Henrique [UNESP]
dc.contributor.authordos Santos, A.
dc.contributor.authorBurba, P.
dc.contributor.institutionUniversidade Estadual Paulista (Unesp)
dc.contributor.institutionInstituto Nacional de Pesquisas da Amazônia (INPA)
dc.contributor.institutionCatholic Univ Brasilia
dc.contributor.institutionIQSC
dc.contributor.institutionInst Spectrochem & Appl Spect
dc.date.accessioned2014-05-20T15:29:44Z
dc.date.available2014-05-20T15:29:44Z
dc.date.issued2003-12-04
dc.description.abstractThe influence of structural features of tropical river humic substances (HS) on their capability to reduce mercury(II) in aqueous solutions was studied. The HS investigated were conventionally isolated from Rio Negro water-Amazonas State/Brazil by means of the collector XAD 8. In addition, the isolated HS were on-line fractionated by tangential-flow multistage ultrafiltration (nominal molecular-weight cut-offs: 100, 50, 30, 10, 5 kDa) and characterized by potentiometry and UV/VIS spectroscopy. The reduction of Hg(II) ions to elemental Hg by size-fractions of Rio Negro HS was assessed by cold-vapor AAS (CVAAS). UV/VIS spectrometry revealed that the fractions of high molecular-size (F-1 > 100 kDa and F-2: 50-100 kDa) have a higher aromaticity compared to the fractions of small molecular-size (F-5: 5-10 kDa, F-6: < 5 kDa). In contrast, the potentiometric study showed different concentration of functional groups in the studied HS fractions. The reduction of Hg(II) by aquatic HS fractions at pH 5 proceeded in two steps (I, II) of slow first order kinetics (t(1/2) of I: 160 min, t(1/2) of II: 300 min) weakly influenced by the molecular-size, in contrast to the differing degree of Hg(II) reduction (F-5 > F-2 > > F-1 > F-3 > F-4 > > F-6). Accordingly, Hg(II) ions were preferably reduced by HS molecules having a relatively high ratio of phenolic/carboxylic groups and a small concentration of sulfur. From these results a complex 'competition' between reduction and complexation of mercury(II) by aquatic HS occurring in tropical rivers such as the Rio Negro can be suggested. (C) 2003 Elsevier B.V. All rights reserved.en
dc.description.affiliationUNESP, Inst Chem, BR-14800900 Araraquara, SP, Brazil
dc.description.affiliationINPA, BR-69083000 Manaus, Amazonas, Brazil
dc.description.affiliationCatholic Univ Brasilia, Brasilia, DF, Brazil
dc.description.affiliationIQSC, Inst Chem, Sao Carlos, SP, Brazil
dc.description.affiliationInst Spectrochem & Appl Spect, D-44139 Dortmund, Germany
dc.description.affiliationUnespUNESP, Inst Chem, BR-14800900 Araraquara, SP, Brazil
dc.format.extent699-707
dc.identifierhttp://dx.doi.org/10.1016/S0039-9140(03)00351-5
dc.identifier.citationTalanta. Amsterdam: Elsevier B.V., v. 61, n. 5, p. 699-707, 2003.
dc.identifier.doi10.1016/S0039-9140(03)00351-5
dc.identifier.issn0039-9140
dc.identifier.orcid0000-0002-2042-018X
dc.identifier.urihttp://hdl.handle.net/11449/39238
dc.identifier.wosWOS:000186732700014
dc.language.isoeng
dc.publisherElsevier B.V.
dc.relation.ispartofTalanta
dc.relation.ispartofjcr4.244
dc.relation.ispartofsjr1,186
dc.rights.accessRightsAcesso restrito
dc.sourceWeb of Science
dc.subjectmercury(II) reductionpt
dc.subjectaquatic humic substancespt
dc.subjectmolecular-size fractionationpt
dc.subjectmultistage ultrafiltrationpt
dc.titleReduction of mercury(II) by tropical river humic substances (Rio Negro) - Part II. Influence of structural features (molecular size, aromaticity, phenolic groups, organically bound sulfur)en
dc.typeArtigo
dcterms.licensehttp://www.elsevier.com/about/open-access/open-access-policies/article-posting-policy
dcterms.rightsHolderElsevier B.V.
unesp.author.lattes5228846314663888[4]
unesp.author.orcid0000-0002-2042-018X[4]

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