Effect of Alkaline Medium on Hydrothermal Synthesis of Boehmite

The transformation of gibbsite into boehmite upon hydrothermal treatment at 200°C in 1.5 wt % NaOH have been studied by X-ray powder diffraction, IR spectroscopy, Brunauer–Emmett–Teller, differential scanning calorimetry, and scanning electron microscopy. The stages of the process have been determined. The transformation of gibbsite into boehmite in an alkaline medium takes 1 h and is accompanied by the splitting of gibbsite into boehmite plates with an average particle size of ~1 μm. It has been shown that, upon hydrothermal treatment of gibbsite in a 1.5 wt % NaOH solution, lamellar boehmite particles are formed for 24 h. This makes it possible to recommend the synthesized powder boehmite to be used as an additive to oils, in the production of concrete, fire retardants, and as an intermediate phase in the synthesis of α‑Al2O3 powders