HAL will be down for maintenance from Friday, June 10 at 4pm through Monday, June 13 at 9am. More information
Skip to Main content Skip to Navigation
Journal articles

Selenite Uptake by Ca–Al LDH: A Description of Intercalated Anion Coordination Geometries

Abstract : Layered double hydroxides (LDHs) are anion exchangers with a strong potential to scavenge anionic contaminants in aquatic environments. Here, the uptake of selenite (SeO32–) by Ca–Al LDHs was investigated as a function of Se concentration. Thermodynamic modeling of batch sorption isotherms shows that the formation of SeO32–-intercalated AFm (hydrated calcium aluminate monosubstituent) phase, AFm-SeO3, is the dominant mechanism controlling the retention of Se at medium loadings. AFm-Cl2 shows much stronger affinity and larger distribution ratio (Rd ∼ 17800 L kg–1) toward SeO32– than AFm-SO4 (Rd ∼ 705 L kg–1). At stoichiometric SeO32– loading for anion exchange, the newly formed AFm-SeO3 phase results in two basal spacing, i.e., 9.93 ± 0.06 Å and ∼11.03 ± 0.03 Å. Extended X-ray absorption fine structure (EXAFS) spectra indicate that the intercalated SeO32– forms inner-sphere complexes with the Ca–Al–O layers. In situ X-ray diffraction (XRD) shows that basal spacing of Ca–Al LDHs have a remarkable linear relationship with the size of hydrated intercalated anions (i.e., Cl–, SO42–, MoO42–, and SeO32–). Contrary to AFm-SeO3 with inner-sphere SeO32– complexes in the interlayer, the phase with hydrogen-bonded inner-sphere complexed SeO32– is kinetically favored but thermodynamically unstable. This work offers new insights about the determination of intercalated anion coordination geometries via XRD analyses.
Document type :
Journal articles
Complete list of metadata

Contributor : Nathalie Pothier Connect in order to contact the contributor
Submitted on : Thursday, September 27, 2018 - 8:20:09 AM
Last modification on : Tuesday, May 10, 2022 - 3:25:01 PM



Bin Ma, Alejandro Fernandez-Martinez, Sylvain Grangeon, Christophe Tournassat, Nathaniel Findling, et al.. Selenite Uptake by Ca–Al LDH: A Description of Intercalated Anion Coordination Geometries. Environmental Science and Technology, American Chemical Society, 2018, 52 (3), pp.1624 - 1632. ⟨10.1021/acs.est.7b04644⟩. ⟨insu-01882419⟩



Record views