Water Molecules in Hydrotalcite-like Layered Double Hydroxides: Interplay between the Hydration of the Anions and the Metal Hydroxide Layer

2015 ◽  
Vol 641 (5) ◽  
pp. 927-934 ◽  
Author(s):  
Shivanna Marappa ◽  
P. Vishnu Kamath
Keyword(s):  
Layered Double Hydroxides ◽  
Metal Hydroxide ◽  
Water Molecules ◽  
Double Hydroxides

Molecular Dynamics Simulation of Interlayer Structure and Hydration Properties of Glycine Intercalated Layered Double Hydroxides

2011 ◽  
pp. 242-250
Author(s):  
Guo-Xiang Pan ◽  
Feng Cao ◽  
Pei-Song Tang ◽  
Hai-Feng Chen ◽  
Zhe-Ming Ni ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bond ◽  
Layered Double Hydroxides ◽  
Interlayer Spacing ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Hydration Properties ◽  
Interlayer Structure ◽  
Double Hydroxides ◽  
Water Contents

Interlayer structure, hydrogen-bond, hydration and swelling properties of glycine intercalated layered double hydroxides (LDHs-Gly) were investigated with molecular dynamics (MD) methods. The results show that the interlayer spacing dc increases as hydration level increases. The computed hydration energies reach the most negative values at low water contents and change rapidly over the range 1 = NW = 6, and slowly and gradually approach the potential energy for bulk SPC water at NW > 6. But there are no local minima in the energy over the entire hydration range. This result suggests that LDHs-Gly tend to absorb water continuously in water-rich environments and enhance swelling to delaminate the hydroxide layers. The interlayers of LDHs-Gly exhibit complex hydrogen-bond network. With water content increasing, the glycine molecules progressively change their orientation from parallel to the layers to nearly perpendicular. Water molecules firstly form hydrogen-bond with M-OH layers at low water contents. While the hydroxide layers gradually get to saturation state at Nw > 3. And then water molecules continuously fill the interlayer to expand interlayer spacing.

scholarly journals Efficient Exfoliation of Layered Double Hydroxides; Effect of Cationic Ratio, Hydration State, Anions and Their Orientations

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 346 ◽  
Author(s):  
Jayakumar Karthikeyan ◽  
Helmer Fjellvåg ◽  
Silje Bundli ◽  
Anja Olafsen Sjåstad
Keyword(s):  
Layered Double Hydroxides ◽  
Particle Morphology ◽  
Clear Correlation ◽  
Water Molecules ◽  
Nitrate Anion ◽  
Hydration State ◽  
Double Hydroxides ◽  
Charge Balancing ◽  
Nitrate Anions ◽  
Anion Type

The exfoliation ability of nitrate based Mg1−xAlx(OH)2(NO3)x·mH2O layered double hydroxides (Mg-Al LDH) in formamide into single or multilayer nanosheets depends strongly on nitrate anion orientation and layer charge. Our systematic studies used materials that were likely to disclose differences with respect to anion type and their concentrations in the interlayer gallery. We assured to avoid any carbonate incorporation into the galleries for nitrate, chloride, iodide, and sulfate based Mg-Al LDHs. Furthermore, the comparative exfoliation experiments were conducted for fully hydrated samples with as similar particle morphology as possible. The exfoliation of nitrate Mg-Al LDH is far superior to similar clays with carbonate, sulfate, chloride, or iodide as charge balancing anions. Quantitative analysis of exfoliation yield for pre-treated, fully hydrated samples, shows an optimum composition for exfoliation into single nanosheets of around x ≈ 0.25, while double or triple layered sheets are encountered for other x-values. We observe a clear correlation between the expansion of the interlayer gallery due to progressing tilts of nitrate anions and water molecules out of the horizontal interlayer plane, suspension turbidity, and degree of exfoliation. The established correlations extends to nitrate Ni-Al LDH materials. We finally claim that morphology is a dominating parameter, with house-of-card morphology particles exfoliation far less than platelet-like particles. Hence, hydrothermal treatment may be favorable to enhance exfoliation yields.

Thermal evolution of Mg–Al and Ni–Al layered double hydroxides: the structure of the dehydrated phase

2016 ◽  
Vol 72 (6) ◽  
pp. 651-659 ◽  
Author(s):  
Svetlana Cherepanova ◽  
Natalya Leont'eva ◽  
Vladimir Drozdov ◽  
Vladimir Doronin
Keyword(s):  
Layered Double Hydroxides ◽  
Thermal Evolution ◽  
Water Molecules ◽  
Initial Structure ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
X Ray ◽  
Turbostratic Disorder ◽  
Diffraction Patterns ◽  
Double Hydroxides

Simulation of X-ray diffraction patterns on the basis of the models of one-dimensional disordered crystals was used to investigate the structure of the dehydrated phase produced by dehydration of Mg–Al and Ni–Al layered double hydroxides at a temperature of ∼473–498 K. It was found that the removal of water molecules transforms the initial structure, which is a mixture of 3R1and 2H1polytypes, into a structure that comprises preferentially fragments of 3R2and 1Hpolytypes and has some turbostratic disorder.

scholarly journals Hydrotalcites in Construction Materials

2020 ◽  
Vol 10 (22) ◽  
pp. 7989
Author(s):  
Anna-Marie Lauermannová ◽  
Iva Paterová ◽  
Jan Patera ◽  
Kryštof Skrbek ◽  
Ondřej Jankovský ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Radioactive Waste ◽  
Construction Industry ◽  
Layered Double Hydroxides ◽  
Building Materials ◽  
Construction Materials ◽  
Water Molecules ◽  
Wide Range ◽  
Waste Repository ◽  
Double Hydroxides

Hydrotalcites are layered double hydroxides displaying a variety of stoichiometry caused by the different arrangement of the stacking of the layers, ordering of the metal cations, as well as the arrangement of anions and water molecules, in the interlayer galleries. The compounds of the hydrotalcite group show a wide range of the possible applications due to their specific properties, such as their large surface area, ion exchange ability, the insolubility in water and most of the organic sorbents, and others. Affordability, wide possibilities of manufacturing, and presence of sufficient natural deposits make hydrotalcites potentially very useful for the construction industry, as either a building material itself or an additive in mortars, concrete or in polymers composites used in constructions. Similar possible application of such material is in leakage control in a radioactive waste repository. The effect of use of these materials for ion exchange, anti-corrosion protection, radioactive ions containment, and similar purposes in building materials is examined in this review.

Design and synthesis of metal hydroxide three-dimensional inorganic cationic frameworks

2018 ◽  
Vol 47 (10) ◽  
pp. 3339-3345
Author(s):  
Long Yuan ◽  
Keke Huang ◽  
Wenchun Feng ◽  
Baiyan Li ◽  
Changmin Hou ◽  
...  
Keyword(s):  
Rare Earth ◽  
Transition Metal ◽  
Layered Double Hydroxides ◽  
Three Dimensional ◽  
Metal Hydroxide ◽  
Design And Synthesis ◽  
Double Hydroxides

We developed the largest family of three-dimensional inorganic cationic frameworks that built by edge-sharing rare-earth and transition metal hydroxide polyhedral units,which indicates the successful conversion of layered double hydroxides (LDHs) and layered rare-earth hydroxides (LREHs) to 3-D structures.

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