Nanogibbsite: Synthesis and characterization

Nanogibbsite crystals synthesis and progression were analyzed by XRD and FTIR spectroscopy. TEM indicated the pseudo-hexagonal shape nanostructure. [Display omitted] . ► A simple methodology is presented to synthesize nanogibbsite particulates using supersaturated Al(OH) 3 solutions around pH 4.6. ► A plausible mechanism of nanogibbsite crystallization is proposed based on macroscopic and microscopic experimental data. ► Inhibiting role of chloride on nanogibbsite formation is discussed and further investigations are warranted. Nanogibbsite was synthesized using a supersaturated Al(OH) 3 solution which was prepared by titration of AlCl 3 with NaOH at pH 4.6. Excess chloride ions in the system were stripped off by dialyzing the Al(OH) 3 suspension against distilled water. The dialysis step is critical for initiation of gibbsite crystallization or the Al(OH) 3 suspension would remain amorphous. Chloride ions seem to mask the seeding sites and so retard the overall process of gibbsite formation. When subjected to heat treatment, gibbsite → alumina conversion occurred by two mechanisms. Nanogibbsite → α-alumina phase transition occurred forming χ- and κ-alumina polymorphs.