Redox reactions of nitrite ions on the surface of colloidal magnetite particles coated with chondroitin sulfate |
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Authors: | M Aoyagi H Sato K Yagi N Fukuda S Nishimoto |
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Institution: | (1) Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University Kyoto 606-8501, Japan, JP;(2) Department of Polymer Chemistry Graduate School of Engineering Kyoto University, Kyoto 606-8501, Japan e-mail: hsato@polym.kyoto-u.ac.jp Tel.: +81-75-7534812 Fax: +81-75-7535065, JP;(3) Department of Mechanical Engineering Mie University, 1515 Kamihama Tsu 514-0008, Mie, Japan, JP |
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Abstract: | Colloidal magnetite particles coated with chondroitin sulfate (abbreviated as Fe/CS) were prepared under conditions of varying
Fe(II) fractions at a fixed Fe concentration and a given concentration of CS. The average size of the magnetite core region
was estimated as 7 nm from transmittance electron microscopy measurements, while the size of the Fe/CS particles ranged 155–175 nm,
as estimated using Rayleigh scattering measurements by reference to a control size derived from the dynamic light scattering.
The reaction of various Fe/CS with NO−
2 in aqueous solutions was determined by fluorometry using 2,3-diaminonaphthalene as a probe and by gas chromatography–mass
spectrometry. The concentrations of NO−
2 in the reaction mixtures decreased in the presence of Fe/CS to a greater extent under Ar compared with aerobic conditions.
The reactivity of Fe/CS toward NO−
2 under aerobic conditions increased with decreasing the size of Fe/CS particles or with increasing content of Fe(III) in the
Fe/CS solutions, but was independent of the Fe(II) fraction in the preparation process. While CS molecules had no influence
on the NO−
2 decomposition, those coated with the magnetite core may prevent the diffusion of NO−
2 to be adsorbed on the core surfaces. NO−
2 was concluded to undergo redox reactions with Fe(II) and Fe(III) located on the core surface of magnetite crystalline structures
of Fe/CS.
Received: 12 April 2000/Accepted: 9 August 2000 |
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Keywords: | Colloidal magnetite particles Chondroitin sulfate Nitrite ions Redox reactions Core surface |
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