Hydrotalcite-like compounds double hydroxides

New developments in the use of silicates to improve flame retardancy have arisen from the use of synthetic anionic clays that correspond to the family of lamellar mixed metal hydroxides, commonly named layered double hydroxides (LDH) or hydrotalcite-like compounds.17... 

Layered double hydroxides (LDHs) are a unique type of clay with anion exchange capacity. In nature, they are found in the carbonated hydrotalcite-like compounds... 

The hydroxycarbonate precursors showed dif action patterns consistent with the layered double hydroxide structure proposed for hydrotalcite-like compounds, i.e., brucite-like sheets formed by OH groups and cations (Mg and AP ) in octahedral coordination. Water molecules and charge-compensating COs anions are located in the interlayers. The hydrotalcite-like precursor composition is [Mg,, .Al,(0H)2] (C03), . mH20 with r = Al/(A1+Mg) the stoichiometric hydrotalcite compound, Mg6Al2(0H)i6C03.4H20, is obtained for r = 0.25. Upon thermal decomposition at 673 K, the hydroxycarbonate precursors lose... 

Anionic clays are a family of lamellar mixed metal hydroxides, also called hydrotalcite-like compounds (HTlcs) or, more often, layered double hydroxides... 

Under microwave irradiation, in situ polymerization constitutes an alternative method for preparing poly(ethylene terephthalate) (PET)/layered double hydroxide (LDH) nanocomposites. LDHs are also known as anionic clays or hydrotalcite-like compounds. To overcome the lack of compatibility between PET and LDHs that contain purely inorganic anions, LDHs were modified with dodecyl sulfate prior to sample preparation. The preparation time was considerably reduced, and the inorganic filler was well dispersed and exfoliated in the polymer matrix. The nanocomposites thus obtained were thermally more stable than original PET,... 

Hydrotalcite-like compounds (MgAlFe) containing Mg2+, Fe3+ and AB+ were used for the transesterification of soybean oil with methanol to produce biodiesel. Under optimized conditions of oil to methanol ratio of 1 21 and a temperature of 65° C with 3% catalyst and 4 h of reaction period resulted in 85% conversion [67], In a similar study, hydrotalcite like compounds containing Mg2+, Ni2+ and A13+ leered double hydroxide catalysts were used for... 

Clays are layered aluminosilicates that exhibit cation exchange capabilities and adsorption properties, while layered double hydroxides are aiuon exchangers with a hydrotalcite-like structure. Both have been incorporated in CPEs and exploited in electroanalysis, mostly to preconcentrate target analytes (usually by ion exchange or organic compounds by adsorption) prior to their voltammetric detectiOTi. 

Figure 6.1 Stacking of brucite-like layers forming the hydrotalcite structure. Reprinted from Coordination Chemistry Reviews, Vol. 181, Vicente Rives and Maria Angeles Ulibarri, Layered double hydroxides (LDH) intercalated with metal coordination compounds and oxometalates, pp. 61 - 120, 1999, with permission from Elsevier.

Hydrotalcite (HT)-like compounds are a family of anionic clays that are also known as layered double hydroxides (LDH) (Wang and Jehng, 2011). They are represented by the general formula where are divalent anions... 

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