Nanoscale size effects on uranium(VI) adsorption to hematite.
U(VI) adsorption on aerosol-synthesized hematite particles ranging in size from 12 to 125 nm was studied to explore nanoscale size effects on uranium adsorption. Adsorption on 70 nm aqueous-synthesized particles was also investigated to examine the effect of the synthesis method on reactivity. Equilibrium adsorption was measured over pH 3-11 at two U(VI) loadings. Surface complexation modeling, combined with adjustment of adsorption equilibrium constants to be independent of site density and surface area, provided a quantitative reaction-based framework for evaluating adsorption affinity and capacity. Among the aerosol-synthesized particles, the adsorption affinity decreased as the particle size increased from 12 to 125 nm with similar intermediate affinities for 30 and 50 nm particles. X-ray absorption fine structure spectroscopy measurements suggest that the differences in adsorption affinity and capacity are not the result of substantially different coordination environments of adsorbed U(VI).
Zeng
Hui
H
Departments of Energy, Environmental and Chemical Engineering and of Earth and Planetary Sciences and Center for Materials Innovation, Washington University, St. Louis, Missouri 63130, USA.
Singh
Abhas
A
Basak
Soubir
S
Ulrich
Kai-Uwe
KU
Sahu
Manoranjan
M
Biswas
Pratim
P
Catalano
Jeffrey G
JG
Giammar
Daniel E
DE
D000143:Acids / Q000737:chemistry; D000327:Adsorption; D000468:Alkalies / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry*; D007700:Kinetics; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D013057:Spectrum Analysis; D013499:Surface Properties; D017186:Titrimetry; D014501:Uranium / Q000737:chemistry*
D000143:Acids; D000468:Alkalies; D005290:Ferric Compounds; C000499:ferric oxide; D014501:Uranium