Nanogibbsite: Synthesis and characterization

Nanogibbsite was synthesized using a supersaturated Al(OH)3 solution which was prepared by titration of AlCl3 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.

Nanogibbsite crystals synthesis and progression were analyzed by XRD and FTIR spectroscopy. TEM indicated the pseudo-hexagonal shape nanostructure..Figure optionsDownload high-quality image (137 K)Download as PowerPoint slideResearch highlights
► 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.