One-pot synthesis of Mg Al layered double hydroxide (LDH) using MgO and metakaolin (MK) as precursors

Layered double hydroxides (LDH) are a class of basic inorganic layered compounds, which widely used in the fields adsorption and catalysis owing to their unique structure properties. In previous studies, costly soluble Al salts or Al(OH)3 were as sources for synthesis MgAl LDH. The present work proposes facile one-pot method synthesize LDH water bath with MgO MK precursors, both obtained from abundant natural resources. effects liquid/solid ratio (30:1 60:1), temperature (55–90 °C) alkali concentration (3 6 mol/L) investigated on composition characteristics synthetic products. samples characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermogravimetric analysis (TGA), Scanning electron microscope (SEM) Nuclear magnetic resonance (NMR). Findings showed that highly alkaline solution (6 M NaOH) promoted dissolution MK, resulting release trivalent formation Increasing also led faster released more Si, resulted zeolite. More importantly, it was found Mg2+ during hydrolysis combined Al-containing substances directly precipitate LDH, whereas its hydration product, i.e., brucite, remained stable condition little participate Zeolites may form depending Si/Al is governed various parameters. findings not only shed lights reaction mechanism between role key conditions zeolitic phases, but demonstrated feasibility using widely-available, low-cost minerals produce commercial adsorbents/catalysts.