Novel Approach to Synthetic Mg(II)Fe(III) Layered Double Hydroxide Using Waste Serpentine Tailings

AbstractLayered double hydroxides (LDHs) are usually synthesized by a conventional coprecipitation using inorganic salts. In this study, waste serpentine tailings (WSTs), including MgO and Fe2O3 with contents of 34 and 4.27%, were used to prepare Mg(II)Fe(III) LDHs. Firstly, WSTs were leached in a nitric acid solution at 90°C using a refluxing process in the presence of a solid∶liquid ratio of 1∶4. By a countercurrent leaching process, the acidity of the leaching solution not only was decreased but Mg and Fe were also enriched. Subsequently, waste iron was put into the leaching solution, which was used to adjust molar ratio of magnesium to ferrum. Finally, 30% NaOH solution was slowly put into the described solution to synthesize Mg(II)Fe(III)LDHs. The structure and surface morphology of the LDHs were characterized by an X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed typical structure of Mg(II)Fe(III) brucitelike sheets with exchangeable capability in an interlayer space. This study indicated that it was feasible to synthesize Mg(II)Fe(III) LDHs using WSTs and waste iron.