Effect of ferrous ion concentration on the kinetics of radiation-induced iron-oxide nanoparticle formation and growth

Magnetite nanoparticles were formed by γ-radiolysis of solutions containing different initial concentrations of FeSO 4 without any other chemical additives. The particles formed in a given [Fe 2+ ] 0 had a narrow size distribution and the average size increased with [Fe 2+ ] 0 . Five hour irradiatio...

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Bibliographic Details
Published in:Physical chemistry chemical physics : PCCP 2016-12, Vol.19 (1), p.695-78
Main Authors: Sutherland, T. I, Sparks, C. J, Joseph, J. M, Wang, Z, Whitaker, G, Sham, T. K, Wren, J. C
Format: Article
Language:English
Subjects:
Austenitic stainless steels
Formations
Imaging
Irradiation
Nanostructure
Oxidation
Reaction kinetics
Time dependence
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Summary:Magnetite nanoparticles were formed by γ-radiolysis of solutions containing different initial concentrations of FeSO 4 without any other chemical additives. The particles formed in a given [Fe 2+ ] 0 had a narrow size distribution and the average size increased with [Fe 2+ ] 0 . Five hour irradiation at 0.8 Gy s −1 produced an average size ranging from 23 ± 2 nm to 300 ± 40 nm in 0.1 mM or 10 mM [Fe 2+ ] 0 solutions, respectively. To ascertain the size-determining mechanism, the kinetics of γ-radiation-induced particle formation and growth were investigated by simultaneously analyzing the [H 2 (g)] in the headspace, the [Fe II ] and [Fe III ] dispersed in solution, UV-Vis absorbances at 304 nm and 380 nm, and the pH of the solution. The particles formed were characterized by TEM imaging and various spectroscopic analyses. For a given [Fe 2+ ] 0 the time-dependent behaviours of different analyses collectively show three distinct kinetic stages of iron oxidation. The [Fe 2+ ] 0 affects the oxidation kinetics of different stages and hence, the oxidation yields and the size of particles formed after irradiation. The main processes which cause the observed kinetics and yields in the three stages are proposed. Magnetite nanoparticles with a narrow size distribution were produced via gamma-radiolysis of FeSO 4 solutions. The average particle size increased with [Fe 2+ ] 0 . A multistage mechanism (supported by radiolysis kinetic modelling) is described that can explain the observed dependence of particle size on [Fe 2+ ] 0 .
ISSN:1463-9076
1463-9084
DOI:10.1039/c6cp05456k