Effect of copper content on the synthesis and properties of (Mg4−xCux)Al2OH12CO3, nH2O layered double hydroxides

In this paper, the substitution of Mg by Cu on the synthesis and properties of (Mg4−xCux)Al2OH12CO3, nH2O LDHs has been studied. Samples have been synthesized by the coprecipitation method using varying pH method. Physicochemical characterization of the obtained samples was performed by a combination of techniques such as X-ray diffraction, SEM, BET-specific surface area, UV–Visible spectrometry, EPR spectrometry, and thermogravimetric analysis. For all the syntheses, whatever the Mg/Cu ratio, a single phase was obtained. For low copper contents (x < 2.6), the single phase is a rhombohedral LDH. For higher copper contents, a symmetry decrease was observed and the layered hydroxide compound is monoclinic, due to distorted Cu(OH)2 octahedra by Jahn–Teller effect. Additionally, thermal stability of the compounds decreases when Cu content increases. Samples with the monoclinic cell do not show any affinity for nitrates and an even higher affinity for carbonates compared to Mg4Al2-LDH. For the samples with the LDH structure, the captured nitrate content increases as the copper content increases but remains limited. All the samples also lead to amorphous mixed oxide nanoparticles when heated at moderate temperature.