Thermal stability changing caused by chromium (iii) in the carbonated magnesium-aluminum hydrotalcite

Abstract

There are several purposes for investigating hydrotalcite clays and one of them is due to its importance as an anionic adsorbent and ion exchanger, which make them capable of removing various pollutants from water. The most common hydrotalcite structure is based on double lamellar hydroxide of magnesium and aluminum, containing carbonate anions in the interlayer space. However, it is common to investigate the co-substitution of aluminum with other trivalent cations, especially transition metal cations, due to their binding properties. In this work, it was investigate the co-substitution of chromium (III) and aluminum in a sample of magnesium-aluminum carbonated hydrotalcite, comparing it with the same composition without this co-substitution. Thermal stability, crystallinity and morphology were investigated, showing that chromium contributes to the adsorptive capacity at low temperature.

Esterification of biomass-derived levulinic acid using molybdate-intercalated hydrotalcite materials

“…The presence of trivalent chromium in the framework makes the lamellaer of the LDH structure more homogenous, hence preventing early dehydroxylation at lower temperatures. 45 The total weight losses observed during the dehydration, dehydroxylation and decarbonation process of the MgFe, MgAl and MgCr samples were 43, 33 and 40%, respectively. The TGA profiles of the molybdenum-intercalated samples show a delay in the dehydroxylation step and less weight loss, which clearly indicates the higher thermal stability compared to the molybdenum-free samples.…”