Optimisation of the synthesis parameters of mechanochemically prepared CaAl-layered double hydroxide

• Synthesis of CaAl-LDH by manual grinding and two-step milling
• Identifying the optimum synthesis parameters
• Characterisation of the sample prepared under optimal conditions

In this work, not so commonly used methods, manual grinding and milling, were applied in an attempt of preparing phase-pure CaAl-LDH (CaAl-layered double hydroxide). For manual grinding a mortar and a pestle and the components with some added water or NaOH solution were used. Milling was a two-step procedure: dry milling was followed by milling in the presence of minute (and controlled) amount of water. The thus prepared samples were characterised by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). It was proven that even though manual grinding did produce LDH, only mechanochemical energy provided by the two-step milling procedure was able to transform the precursors nearly completely to CaAl-LDH. Optimisation of the milling parameters could reproducibly lead to close-to-phase-pure CaAl-LDH.