Open AccessSAXS study of the formation and structure of polynuclear thorium(IV) colloids and thorium dioxide nanoparticles
Author(s) -
Zhai Baihui,
Tian Qiang,
Li Na,
Yan Minhao,
Henderson Mark J.
Publication year - 2022
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s1600577521012923
Subject(s) - radius of gyration , thorium , agglomerate , small angle x ray scattering , colloid , scattering , chemistry , gyration , dispersion (optics) , nanoparticle , materials science , analytical chemistry (journal) , polymer , uranium , nanotechnology , chromatography , physics , optics , composite material , organic chemistry , geometry , mathematics , metallurgy
Stable actinide colloids and nanoparticles are of interest because of their potential to affect the transportation of radionuclides in the near‐field of a nuclear waste repository. At high concentrations, thorium(IV) can precipitate to form intrinsic colloids. In the present study, polynuclear thorium colloids and thorium dioxide crystallites, formed by the condensation of hydrolyzed Th 4+ solutions (3 m M ; initial pH 5.5) aged for up to 18 months, were studied using small‐angle X‐ray scattering. Scattering profiles were fitted using a unified Guinier/power‐law model (Beaucage model) to extract the radii of gyration and Porod exponents. Analysis of the scattering profiles from a dispersion aged for 5 months indicated that both polymer coils and more compacted structures (radius of gyration R g ≃ 10 nm) were present, which translated in the Kratky plots as a plateau and a peak maximum, respectively. After 18 months, the SAXS data were consistent with the presence of agglomerates of ThO 2 particles suspended in aqueous solution (pH 3.2; [Th] = 1.45 m M ). The measured radius of gyration ( R g ) of the agglomerates was 5.8 nm, whereas the radius of the ThO 2 particles was 2.5 nm.