Abstract:
The synthesis of Mg-Al, Ca-Al, Zn-Al and Cu-Al layered double hydroxides (LDHs) was
investigated with a one-step wet mechanochemical route. The research aims to expand on the
mechanochemical synthesis of LDH using a mill designed for wet grinding application. A 10%
slurry of solids was added to a Netzsch LME 1 horizontal bead mill and milled for 1 h at 2000 rpm.
Milling conditions were selected according to machine limitations and as an initial exploratory
starting point. Precursor materials selected consisted of a mixture of oxides, hydroxides and basic
carbonates. Samples obtained were divided such that half was filtered and dried at 60 ◦C for 12 h.
The remaining half of the samples were further subjected to ageing at 80 ◦C for 24 h as a possible
second step to the synthesis procedure. Synthesis conditions, such as selected precursor materials
and the MII:MIII ratio, were adapted from existing mechanochemical methods. LDH synthesis prior
to ageing was successful with precursor materials observably present within each sample. No Cu-Al
LDH was clearly identifiable. Ageing of samples resulted in an increase in the conversion of raw
materials to LDH product. The research offers a promising ‘green’ method for LDH synthesis without
the production of environmentally harmful salt effluent. The synthesis technique warrants further
exploration with potential for future commercial up-scaling.
