Competitive effect of iron(III) on metal complexation by humic substances: Characterisation of ageing processes

Lippold, Holger; Evans, Nicholas D.M.; Warwick, Peter; Kupsch, H.

doi:10.1016/j.chemosphere.2006.10.045

Cited by 37 publications

(13 citation statements)

References 51 publications

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“…The metals showed similar and homogeneous distributions in all fractions, close to those observed after 15 days, probably indicative of an establishment of equilibrium. These results differ from those obtained by Sargentini et al, 10 where a change was observed 24 h after addition of five metals (Ni, Cu, Zn, Cd and Pb), with a return to a distribution similar to that of the in natura sample after 10 days. Conditions were not identical, with the earlier study being of shorter duration, the NOM (denoted aquatic humic substances) extracted using XAD-8 resin, and the water sample obtained from the Rio Negro in the northern Amazon basin (Brazil).…”

Section: Resultscontrasting

confidence: 57%

“…Some studies have suggested that recently-complexed metal ions are preferentially linked with easily accessible functional groups in the organic molecules, with reaction time determining structural changes in NOM molecules and variations in the contents of dissolved organic carbon (DOC) and metals in the various molecular size fractions. [7][8][9][10] Information is therefore needed to improve understanding of the dynamics of natural aquatic systems containing elevated DOC contents, and here we use the example of the Serra de Itabaiana National Park watershed (Brazil). This environmentally protected region contains the headwaters of rivers that are important both from the perspective of water supplies for human consumption, and for irrigation projects affecting around 100,000 inhabitants of an arid region of Sergipe State in northeast Brazil.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of interactions between natural organic matter and metals by tangential-flow ultrafiltration and ICP OES

Santos¹,

Romão²,

Oliveira³

et al. 2011

J. Braz. Chem. Soc.

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O fracionamento por tamanho molecular da matéria orgânica natural (MON) de amostras de água do Parque Nacional Serra de Itabaiana (Brasil) foi utilizado para caracterização temporal da complexação de íons metálicos. Um sistema de ultrafiltração em cinco estágios foi usado para separar a MON em seis frações (F1: > 100; F2: 100-50; F3: 50-30; F4: 30-10; F5: 10-5; F6: < 5 kDa). A distribuição obtida, inicialmente para amostra in natura, mostrou que metais (Al, Ba, Cr, Cu, Fe, Mn, Ni, Pb e Sr) foram complexados, preferencialmente, pela fração F1, a qual continha maior concentração de carbono orgânico dissolvido (COD). A seguinte ordem decrescente de distribuição de carbono foi obtida: F1 >> F3 > F2 = F4 > F6 > F5. As frações F2 e F5 foram as mais humificadas e F6 a menos humificada. Após 30 dias com adição de elevadas concentrações de metais nas amostras filtradas novas distribuições de COD e metais foram observadas. Maior COD ainda foi encontrado na F1 com teores de carbono decrescendo na seguinte ordem: F1 > F2 > F3 > F4 > F5 > F6. Os metais apresentaram distribuições similares e homogêneas em todas as frações. Valores de log K foram similares para as amostras in natura e para aquelas de 30 dias após a adição dos metais (7,1 e 7,0; 6,6 e 6,9; e 7,2 e 7,0 para Al, Cu e Fe-MON, respectivamente), indicando uma nova condição de equilíbrio na distribuição dos metais após 30 dias. As espécies formadas entre MON e os metais adicionados mostraram um modelo de distribuição que mudou em função do tempo de complexação, indicando uma transformação dos sítios de ligação da MON, sugerindo que o efeito coletivo das frações é mais importante que as propriedades individuais e confirmando que as frações mais humificadas exercem grande influência na complexação de metais em ambientes aquáticos.Molecular size fractionation of the natural organic matter (NOM) in water samples from the Serra de Itabaiana National Park (Brazil) was used to characterize the temporal behavior of metal ion complexation. A special five-stage tangential-flow ultrafiltration device was used to separate NOM in six size fractions (F1: > 100; F2: 100-50; F3: 50-30; F4: 30-10; F5: 10-5; F6: < 5 kDa). The distribution patterns obtained for one in natura sample showed that metals (Al, Ba, Cr, Cu, Fe, Mn, Ni, Pb and Sr) were preferentially complexed by the F1 fraction, which contained higher concentration of dissolved organic carbon (DOC). The following decreasing order of carbon distribution in the different fractions was obtained: F1 >> F3 > F2 = F4 > F6 > F5. Fractions F2 and F5 were the most humified, and F6 the least. New distributions of DOC and metals were observed after 30 days when high concentrations of metals were added to filtered samples. Highest DOC was still found in F1, with carbon contents decreasing in the following order: F1 > F2 > F3 > F4 > F5 > F6. The studied metals presented similar and homogeneous distributions in all fractions. Values of log K were similar for samples in natura and 30 days after addition of metals (7.1 and 7.0, 6.6 and 6.9, ...

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Section: Resultscontrasting

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Characterization of interactions between natural organic matter and metals by tangential-flow ultrafiltration and ICP OES

Santos¹,

Romão²,

Oliveira³

et al. 2011

J. Braz. Chem. Soc.

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“…Among the cations present in natural waters, several cations, such as Fe 3+ and Al 3+ , are known to complex strongly with HA ( Tanizaki et al, 1992;Takahashi et al, 1997;Dupré et al, 1999;Olivié-Lauquet et al, 1999;Allard et al, 2004;Tipping et al, 2002;Tipping, 2005;Lofts et al, 2008), and are therefore a strong potential competitor of REE for HA binding. Experimental studies of a single REE (Lippold et al, 2005;Lippold et al, 2007) and a modeling study of the whole REE series (Tang and Johannesson, 2003) showed that Al and Fe could significantly reduce the amount of the REE bound to HA. Therefore, the question to be asked is if metal competition could modify the REE-HA pattern.…”

Section: Consequences For Cation Competitionmentioning

confidence: 98%

An improved description of the interactions between rare earth elements and humic acids by modeling: PHREEQC-Model VI coupling

Marsac

Davranche

Gruau

et al. 2011

Geochimica et Cosmochimica Acta

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The Humic Ion Binding Model VI (Model VI) -previously used to model the equilibrium binding of rare earth elements (REE) by humic acid (HA) -was modified to account for differences in the REE constant patterns of the HA carboxylic and phenolic groups, and introduced into PHREEQC to calculate the REE speciation on the HA binding sites. The modifications were shown to greatly improve the modeling. They allow for the first time to both satisfactorily and simultaneously model a large set of multi-REE experimental data with the same set of equations and parameters. The use of PHREEQC shows that the light rare earth elements (LREE) and heavy rare earth elements (HREE) do not bind to HA by the same functional groups. The LREE are preferentially bound to carboxylic groups, whereas the HREE are preferentially bound to carboxy-phenolic and phenolic groups. This binding differentiation might lead to a fractionation of REE-HA patterns when competition between REE and other metals occur during complexation. A survey of the available data shows that competition with Al 3+ could lead to the development of HREE-depleted HA patterns. This new model should improve the hydrochemical modeling of the REE since PHREEQC takes into account chemical reactions such as mineral dissolution/ precipitation equilibrium and redox reactions, but also models kinetically controlled reactions and one-dimensional transport.

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“…Ultimately, van der Perk suggests that the humic-metal complexation enhances metal solubility [11], effectively partitioning heavy metals from tropospheric aerosols into atmospheric water. Thus, HULIS strong chelating functional groups may influence the ligand promoted solubility and further mobility of iron in tropospheric aqueous systems [12]. However, the transport and binding strength of the HULIS-Fe system is closely dependent on the relative replaceability of exchangeable cations, as described by Scheffer and Schachtschabel [13] .…”

Section: Introductionmentioning

confidence: 99%

“…In fact, electrochemical potentials determined by Aeschbacher and collaborators suggest that humic substances will be primarily reducing agents to iron [6]. While Fe 3+ is the most abundant species of iron in tropospheric aerosols [8,12], the presence of HULIS in atmospheric water can reduce iron to bivalent species, which is more bioavailable. Although the reduced form of iron can be exchanged by surrounding Al .…”

Section: Introductionmentioning

confidence: 99%

Fate of aqueous iron leached from tropospheric aerosols during atmospheric acidic processing: a study of the effect of humic-like substances

Borgatta¹,

Navea²

2015

WIT Transactions on Ecology and the Environment

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Humic-like substances (HULIS) are complex organic molecules that can be found in the atmosphere as components of tropospheric aerosols or suspended in atmospheric water. HULIS are chelating agents and oxidation-reduction species, therefore these substances can affect the availability of aqueous iron, a heavy metal commonly leached from atmospheric particulate matter upon acidic processing. Specifically, chelating properties allow HULIS to remove aqueous iron from atmospheric water, while their redox properties can alter iron speciation. Ultimately, wet deposition of soluble iron can be influenced not only by HULIS but also by other ubiquitous atmospheric cations. In this work, we investigate the effect of HULIS on iron leached from atmospheric particles in the presence of aluminium ions, an environmentally abundant cation also chelated by HULIS. Colorimetric methods were used to examine the cation exchange (CE) of aluminium ions with both iron (II) and (III) ions in humic acids, a model system for HULIS. An effective chelation of aqueous phase iron with humic acids was observed during suspension experiments, with aqueous iron removed from aqueous phase into a HULIS complex. In addition, the redox properties of humic acids showed no oxidation of iron (II) after chelation by humic acid, but a fraction of iron (III) was reduced into the more bioavailable iron (II). Cation exchange with aluminium suggests that bioavailable iron (II) ions chelate with HULIS in a combination of exchangeable and inexchangeable iron, with a higher proportion of exchangeable iron incidence. Additionally, HULIS interaction with iron (III) ions shows chelating properties as well a reduction potential, producing aqueous and chelated iron (II) ions.

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Competitive effect of iron(III) on metal complexation by humic substances: Characterisation of ageing processes

Cited by 37 publications

References 51 publications

Characterization of interactions between natural organic matter and metals by tangential-flow ultrafiltration and ICP OES

Characterization of interactions between natural organic matter and metals by tangential-flow ultrafiltration and ICP OES

An improved description of the interactions between rare earth elements and humic acids by modeling: PHREEQC-Model VI coupling

Fate of aqueous iron leached from tropospheric aerosols during atmospheric acidic processing: a study of the effect of humic-like substances

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