Abstract:
The synthesis of Mg-Al layered double hydroxide (LDH) was explored, through a one-step
wet mechanochemical route, with the use of a NETZSCH LME 1 horizontal bead mill. Raw materials
selected comprised of a mixture of metallic oxides/hydroxides promoting green synthesis. The
research aims to expand on the understanding of the wet mechanochemical synthesis of Mg-Al LDH
through variation in milling and synthesis parameters. The selected parameters investigated were
rotational speed, retention time, solids loading, bead size and jacket water inlet temperature. Samples
were collected, filtered and dried at 60 °C for 12 h. Unless stated otherwise, or under investigation,
parameters were kept constant at pre-selected conditions adapted from existing literature. LDH
synthesis was deemed to occur successfully at elevated jacket water temperatures of 50 °C and
longer retention times. It was noted that Al(OH)3 XRD peak reduction occurred readily for increased
rotational speeds and residence times, regardless of system temperature. MgO was deemed to react
more readily at elevated temperatures. It was proposed that the amorphitisation and mechanochemical
activation of Al(OH)3 contributed to its dissolution providing the relevant Al3+ ions necessary
for Mg2+ isomorphic substitution. Increasing the system temperature promoted the hydration of
MgO, with the absence of Mg(OH)2 attributed to its contribution as an intermediate phase prior to
LDH formation.
