Interlayer structure of iodide intercalated layered double hydroxides (LDHs)

Abstract

a b s t r a c tThe iodide-containing layered double hydroxides (LDHs) of Mg and Zn with Al crystallize by the inclusion of extensive positional disorder of I À ions in the interlayer region. I À ion given its poor charge to size ratio can neither screen effectively the positive charge nor participate in H-bonding with the metal hydroxide layers. Thereby the I À ions are not stabilized in sites close to the seat of positive charge of the metal hydroxide layers (6c), nor in sites that facilitate H-bonding (3b or 18h). On the other hand, OH À from water can do both and effectively displaces I À from the interlayer.

Effective intercalation of sodium dodecylsulfate (SDS) into hydrocalumite: Mechanism discussion via near-infrared and mid-infrared investigations

“…1(b) (the 2h position = 3.20°) and in the IR results of CaAl-SDS 2 at 1252 and 1220 cm À1 , which were different from the theoretical results for the ion exchange mechanisms of LDHs [29,30]. Thus the occurrence of another reaction under the system of higher SDS concentration is highly possible.…”

Porous Layered Double Hydroxides Synthesized using Oxygen Generated by Decomposition of Hydrogen Peroxide

“…The intensity of the main reflection (003) was significantly reduced, while the (006) intensity increased slightly. This effect can be due to (1) the large atomic scattering factor of the intercalated iodide ions, which may have added considerably to the reflection intensity by the lighter metals, magnesium and aluminum, in the host layers 26, 27 and (2) a decrease in the higher-order crystallinity upon ion exchange, which is a phenomenon that has already been observed for I − intercalated LDHs 28 . The structural order of LDHs intercalated with I − is compromised by stacking faults of the cationic metal hydroxide layers and positional disorder of the large iodide anions.…”

A comprehensive study on iodine uptake by selected LDH phases via coprecipitation, anionic exchange and reconstruction

“…Ahmed et al have reported that ZnAl LDHs are stable materials up to 200°C [31]. Prasanna et al showed that iodide-containing Mg and Zn with Al LDHs release the intercalated iodide while leaching even at neutral pH, due to replacement by hydroxide anions [32]. Mg/Al LDHs with different cationic molar ratios (Mg 2 Al, Mg 3 Al and Mg 4 Al) have been studied as potential matrices for 129 I storage [33,34].…”