Adsorption of cysteine on hematite, magnetite and ferrihydrite: FT-IR, Mössbauer, EPR spectroscopy and X-ray diffractometry studies

In the present paper, the adsorption of cysteine on hematite, magnetite and ferrihydrite was studied using FT-IR, electron paramagnetic resonance (EPR), Mössbauer spectroscopy and X-ray diffractometry. Cysteine was dissolved in artificial seawater (two different pHs) which contains the major constit...

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Bibliographic Details
Published in:Amino acids 2011-01, Vol.40 (1), p.205-214
Main Authors: Vieira, Alessandra P, Berndt, Graciele, de Souza Junior, Ivan G, Di Mauro, Eduardo, Paesano, Andrea Jr, de Santana, Henrique, da Costa, Antonio Carlos S, Zaia, Cássia T. B. V, Zaia, Dimas A. M
Format: Article
Language:English
Subjects:
Adsorption
amino acids
Analytical Chemistry
Biochemical Engineering
Biochemistry
Biomedical and Life Sciences
Cysteine
Cysteine - chemistry
Cystine
Diffraction
Electron Spin Resonance Spectroscopy
Ferric Compounds - chemistry
Ferrosoferric Oxide - chemistry
Infrared spectroscopy
Iron oxides
Life Sciences
Neurobiology
Original Article
Oxidation-Reduction
Prebiotic chemistry
Proteomics
Spectroscopy
Spectroscopy, Mossbauer
Surface chemistry
Surface complexation
X-Ray Diffraction
X-rays
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Summary:In the present paper, the adsorption of cysteine on hematite, magnetite and ferrihydrite was studied using FT-IR, electron paramagnetic resonance (EPR), Mössbauer spectroscopy and X-ray diffractometry. Cysteine was dissolved in artificial seawater (two different pHs) which contains the major constituents. There were two main findings described in this paper. First, after the cysteine adsorption, the FT-IR spectroscopy and X-ray diffractometry data showed the formation of cystine. Second, the Mössbauer spectroscopy did not show any increase in the amount of Fe²⁺ as expected due the oxidation of cysteine to cystine. An explanation could be that Fe²⁺ was oxidized by the oxygen present in the seawater or there occurred a reduction of cystine by Fe²⁺ generating cysteine and Fe³⁺. The specific surface area and pH at point of zero charge of the iron oxides were influenced by adsorption of cysteine. When compared to other iron oxides, ferrihydrite adsorbed significantly (p < 0.05) more cysteine. The pH has a significant (p < 0.05) effect only on cysteine adsorption on hematite. The FT-IR spectroscopy results showed that cystine remains adsorbed on the surface of the iron oxides even after being mixed with KCl and the amine and carboxylic groups are involved in this interaction. X-ray diffractometry showed no changes on iron oxides mineralogy and the following precipitated substances were found along with the iron oxides after drying the samples: cysteine, cystine and seawater salts. The EPR spectroscopy showed that cysteine interacts with iron oxides, changing the relative amounts of iron oxides and hydroxide.
ISSN:0939-4451
1438-2199
DOI:10.1007/s00726-010-0635-y