Characterization of Ferricyanide-Humate Complexes by a Voltammetric Approach

Leita, L.; Mori, Atsuko; Corso, G. Del; Nobili, Maria De; Franco, Irene De; Cenci, R. M.

doi:10.1080/20015891109383

Cited by 7 publications

(7 citation statements)

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“…HAs in fact behave as supramolecules that are able to polymerise, aggregate, form micelles and might also form supramolecular ensembles with other compounds Piccolo, 2002;Steed and Atwood, 2000). As reported by Pacheco et al (2003), the zwitterionic character of HAs allows the interaction of negatively and positively charged groups of HAs, through the micellar formations (Leita et al, 2001(Leita et al, , 2003. In fact, organic cations like pesticides (e.g.…”

Section: Electrochemical Analysis: Amperometric Titrationmentioning

confidence: 95%

“…Since it is well known that HAs' polyelectrolytic nature causes severe interferences in nearly all methods for the determination of chromium species in solution, evaluation of possible interferences at the electrodic surfaces was one of the main aspects to be considered (Korolczuk and Grabarczyk, 2002;Leita et al, 2001Leita et al, , 2003. Moreover, since HAs are also known to contain quinoid moieties, a series of DPS measurements were performed in the absence and in the presence of HAs in 1 mM quinone solution to verify the occurrence of any possible electronic passivation due to adsorption HAs at the surface of the working electrode.…”

Section: Electrochemical Analysis: Amperometric Titrationmentioning

confidence: 99%

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Soil humic acids may favour the persistence of hexavalent chromium in soil

Leita

Margon

Pastrello

et al. 2009

Environmental Pollution

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The interaction between hexavalent chromium Cr(VI), as K 2 CrO 4 , and standard humic acids (HAs) in bulk solution was studied using three complementary analytical methods: UV-Visible spectroscopy, X-ray absorption spectroscopy and differential pulse stripping voltammetry. The observed UV-Vis and X-ray absorption spectra showed that, under our experimental conditions, HAs did not induce reduction of Cr(VI) to its trivalent chemical form. The interaction between Cr(VI) and HAs has rather led to the formation of Cr(VI)-HAs micelles via supramolecular chemical processes. The reported results could contribute towards explaining the relative persistence of ecotoxic hexavalent chromium in soils.

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Section: Electrochemical Analysis: Amperometric Titrationmentioning

confidence: 95%

Section: Electrochemical Analysis: Amperometric Titrationmentioning

confidence: 99%

Soil humic acids may favour the persistence of hexavalent chromium in soil

Leita

Margon

Pastrello

et al. 2009

Environmental Pollution

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“…Ferrocyanide is oxidized to ferricyanide by molecular oxygen in acidic solution (Asperger et al , 1969) and by the manganese oxide birnessite (Rennert et al , 2005a). Conversely, ferricyanide is partially reduced by soil humic substances (Leita et al , 2001) and dissolved organic matter (Bauer et al , 2007). Both iron‐cyanide complexes are sorbed on mineral soil constituents: on iron oxides by monodentate inner‐sphere surface complexes (ferricyanide), as a Prussian‐Blue‐like layer (ferrocyanide) on goethite (Rennert et al , 2005b), and on aluminium oxides by weak outer‐sphere complexes (Cheng & Huang, 1996).…”

Section: Introductionmentioning

confidence: 99%

Interactions of ferricyanide with humic soils and charred straw

Rennert

Kaufhold

Brodowski

et al. 2008

European J Soil Science

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The iron-cyanide complexes ferricyanide, [Fe III (CN) 6 ] 3À , and ferrocyanide, [Fe II (CN) 6 ] 4À , are anthropogenic contaminants in soil. We studied the interactions of ferricyanide with humic soils and charred straw (maize and rye, both charred at 300, 400 and 500°C) by batch experiments and Fourier transform infrared (FTIR) spectroscopy. All soil samples sorbed ferricyanide (up to 8.4 g kg À1 ). Precipitation of a manganese ferrocyanide after reduction of ferricyanide in the moderately acidic to neutral soils was deduced from both FTIR spectroscopy (CN absorption bands at 2069-2065 cm À1 ) and geochemical modelling. Ferricyanide was also adsorbed onto the charred straw. The amounts of iron-cyanide complexes adsorbed increased with increasing charring temperature, with a maximum of 1.71 g kg À1 . An absorption band at 2083 cm À1 indicated weakly adsorbed intermediates of the reduction of ferricyanide to ferrocyanide. This band disappeared in the samples charred at higher temperature, whereas a band at 2026 cm À1 was present in all spectra and became intensified in the high-temperature straw. We attribute this band to ferrocyanide forming inner-sphere complexes, presumably with quinone species of the organic matter. The band at 2026 cm À1 was also present in the spectra of the soils, indicating that soil organic matter also adsorbs ferrocyanide. However, in humic soils the main processes of ferricyanide interaction include reduction to ferrocyanide and precipitation as manganese ferrocyanide. Quantitatively, adsorption on highly aromatic substances plays only a less important role as compared with precipitation.

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“…Because of the polyelectrolytic nature of HAs, interaction of HAs with iron compounds is strongly favored at neutral pH, and interferences at the work electrode surface were controlled and reliability of the analytical response checked on the reversible redox couple quinone-hydroquinone in presence and in absence of HAs, according to Leita et al (2001).…”

Section: Amperometric Titration By Use Of Differential Pulse Strippinmentioning

confidence: 99%

Interaction between Fe-cyanide complex and humic acids

et al. 2006

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The fate of cyanides in soil is strongly influenced by the formation of Fe cyanides, which can interact with organic and inorganic colloids and precipitate as stable compounds. Scarce information is available on the capacity of humic acids to interact with cyano-complexes and thus affect the leaching and prevent the risk of contamination of watertable. Here we show that interaction between humic acids (HAs) and ferricyanide complex led to a formation of ferricyanide-humo micelles, and that the interaction did not imply changes in the original structure of ferricyanide complex.

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Characterization of Ferricyanide-Humate Complexes by a Voltammetric Approach

Cited by 7 publications

References 0 publications

Soil humic acids may favour the persistence of hexavalent chromium in soil

Soil humic acids may favour the persistence of hexavalent chromium in soil

Interactions of ferricyanide with humic soils and charred straw

Interaction between Fe-cyanide complex and humic acids

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