On the Reconstruction Peculiarities of Sol–Gel Derived Mg2−xMx/Al1 (M = Ca, Sr, Ba) Layered Double Hydroxides

Abstract

In this study, the reconstruction peculiarities of sol–gel derived Mg2−xMx/Al1 (M = Ca, Sr, Ba) layered double hydroxides were investigated. The mixed metal oxides (MMO) were synthesized by two different routes. Firstly, the MMO were obtained directly by heating Mg(M)–Al–O precursor gels at 650 °C, 800 °C, and 950 °C. These MMO were reconstructed to the Mg2−xMx/Al1 (M = Ca, Sr, Ba) layered double hydroxides (LDHs) in water at 50 °C for 6 h (pH 10). Secondly, in this study, the MMO were also obtained by heating reconstructed LDHs at the same temperatures. The synthesized materials were characterized using X-ray powder diffraction (XRD) analysis and scanning electron microscopy (SEM). Nitrogen adsorption by the Brunauer, Emmett, and Teller (BET) and Barrett, Joyner, and Halenda (BJH) methods were used to determine the surface area and pore diameter of differently synthesized alkaline earth metal substituted MMO compounds. It was demonstrated for the first time that the microstructure of reconstructed MMO from sol–gel derived LDHs showed a “memory effect”.

Zn-Al Layered Double Hydroxide Thin Film Fabricated by the Sputtering Method and Aqueous Solution Treatment

“…However, it is difficult to control the band gap of LDH when using a metal substrate. Therefore, we focused on the previous metal oxide-based LDH synthesis study [14] and we aim to fabricate LDH containing a host layer, which corresponds to Al doped ZnO (AZO). If a host layer of AZO is present, the organic decomposition reaction occurs via the photocatalytic reaction of ZnO, and the band energy can be controlled using UV irradiation [15].…”

Magnetic Mg-Fe/LDH Intercalated Activated Carbon Composites for Nitrate and Phosphate Removal from Wastewater: Insight into Behavior and Mechanisms

“…This could be ascribed to the excellent formation and efficient dispersion of MgFe nanoparticles within the AC matrix without comprising the crystallographic structure. In contrast, the poor crystalline structure of the SBAC 500 MgFe composite is associated with the disorder and lattice defects of the MgFe crystalline structure due to the high loading of SBAC, which agglomerates or is stacked into LDH segments [ 18 , 34 ].…”

Enhanced Arsenic Removal from Aqueous Solution by Fe/Mn-C Layered Double Hydroxide Composite

“…LDH, as a kind of typical clay inorganic material [19,20], and its special formula could be noted as [M 1-x 2+ M x 3+ (OH) 2 ] x+ (A n-) x/n •yH 2 O, in which M 3+ and M 2+ are the divalent and trivalent cations, respectively. A represents a charge balancing anion in the interlay, n is the valence anion of the interlayer, and x denotes the density of charge, varying from 0.17~0.33 in general [21][22][23][24][25]. Because LDHs are rich in hydroxyl groups and interlayer anions, they can accommodate different ions in their structure [19].…”