Effect of Drying on the Fabrication of MgAl Layered Double Hydroxides

Abstract

This study aimed to evaluate the synthesis of MgAl/LDH from the drying process perspective, evaluating the influence of temperature (75–90 °C) and time (16–20 h) in the drying process. The synthesis was performed, maintaining a ratio of 2:1 of Mg/Al, and the drying was conducted according to a 2 2 experimental design: four axial points and three repetitions at the central point. The surface area and pore diameter ranged from 4.09 to 18.55 m 2 /g and 12.50 to 24.46 nm. Fourier transform infrared (FTIR) analysis indicated the drying-caused variation of the LDH typical bands intensities. Scanning electron microscopy (SEM) images showed the tendency of the increase of agglomeration with the temperature elevation. The drying parameters’ influence was evident for X-ray diffraction (XRD) analysis observing the crystallite size increment, from 13.10 to 38.94 nm, and basal spacing variation, from 7.52 to 7.64 Å. The statistical models for growing crystal and reduction of the basal spacing were physically consistent but with low values of R 2 . The drying time and temperature had a considerable influence on the chemical, physical, structural, and morphological properties of LDH.

Investigating the Impact of the Washing Steps of Layered Double Hydroxides (LDH) on the Electrochemical Performance

“…Considering the peaks at 2 θ indexed to (003), we calculated the basal spacing for all the samples using the Bragg Equation (3) [ 33 ]. Thereafter, from the Equations (4) and (5) [ 34 ], the constant lattices “a” and “c”, which indicate the distance between cations in the lamella and the interlamellar distance, respectively, were calculated. Table 3 displays the calculated values of the basal spacing as well as the constant lattices “a” and “c” for all the samples.…”

“…This could be attributed to the nature of the interlamellar anion and their orientation. Adding to this, the electrostatic interactions between cations, ionic radius of anions within the interlamellar, and the electrostatic force between anions and hydroxyls layers of the lamellar could also be the cause [ 31 , 34 ]. Furthermore, the crystallite sizes for the samples washed with ethanol, acetone, and the ethanol–acetone solution showed an increment compared to the sample washed with deionised water only.…”

“…However, the pore size of the sample washed with the ethanol-acetone solution was 8.575 nm, which was smaller in comparison to the sample washed with acetone. It was reported that the nature of the pore distribution is the result of the formation procedure and the ions located in the layer, while the pore size is influenced by the synthesis route and the relationship between the LDH lamellar [ 34 ]. In addition, Q. Wang et al demonstrated that when a LDH is dispersed into an organic solvent, the molecules of the solvent strips the molecules of water from the surface of the hydroxide metal and replaces them.…”

Advantage of Dimethyl Sulfoxide in the Fabrication of Binder-Free Layered Double Hydroxides Electrodes: Impacts of Physical Parameters on the Crystalline Domain and Electrochemical Performance

“…This hypothesis can also be supported by the behaviors of carbonate anions in the interlamellar of all the electrodes (refer to the pink colored arrows). It is known that more than one atomic species in the interlamellar of LDH possesses a carbonate anion and the corresponding bands are generally distinguished by a D3 h trigonal planar symmetry that shows the vibrations V2, V3, V4 which can be located at 860, 1360, 774 cm −1 , respectively [ 42 , 47 ]. In this work, the recorded bands attributed to carbonate vibrations ranged from 1355 to 1365 cm −1 for all the electrodes indicating the interactions between carbonate groups and water molecules in the interlamellar.…”

Revisiting the Structural Evolution of Hydrotalcite‐Derived Mixed Metal Oxides upon Alkali Metal Doping and Its Impact on Base Catalysis

“…[15][16][17][18][19][20] Among the diverse families of the hydrotalcites, magnesium and alumina hydrotalcites are among the most widely studied materials in the literature. [3,15,[21][22][23] Although different approaches have been disclosed to prepare this class of materials, such as the conventional co-precipitation [17,24] and hydrothermal synthesis methods, [25,26] the use of alkali metals (Na [16,18,27,28] or K [29] ) as the precipitators is frequently adopted. The complete elimination of these residual alkali metal species is very difficult by simple washing.…”