A Simple Mechanochemical Route to Layered Double Hydroxides: Synthesis of Hydrotalcite-Like Mg-Al-NO3-LDH by Manual Grinding in a Mortar

Hydrotalcite-like Mg-Al-NO3-layered double hydroxide (LDH) was successfully prepared in a mortar by manually grinding the hydrated magnesium and aluminum nitrate salts with sodium hydroxide. Various techniques, including XRD, MAS NMR, FTIR, SEM; thermogravimetric and differential thermal analyses (TGA,DTA), Surface area and zeta potential measurements were used to establish a correlation between the LDH samples prepared in the mortar and by co-precipitation. The LDH prepared in the mortar showed all the characteristics of a layered structure but with a lower crystallinity. This product was tested for its anion exhange property with tetraborate anions and 52% of the theoretical exchange capacity was reached. The mortar route does not require heating/refluxing treatment, CO-free atmosphere and solvent as in the conventional preparation methods and allows obtaining LDHs in a short reaction time.