A novel synthesis of high‐area alumina via H2O2‐precipitated boehmite from sodium aluminate solutions

Abstract

A novel procedure was devised, whereby crystalline boehmite, γ-AlO(OH), was efficiently precipitated from sodium aluminate solutions, NaAlO 2 (aq), following controlled addition of H 2 O 2 aqueous solution. The effects of the aluminate solution variables (viz. concentration, volume, caustic ratio, pH and temperature), as well as the H 2 O 2 /Al 2 O 3 molar ratio, on the amount and composition of the yield, were examined. Accordingly, optimal conditions for 98% recovery of the aluminium content of the parent aluminate solution were realized. The remaining NaOH can be recycled and used to extract further amounts of aluminium from bauxite (Bayer process). Thermal stability of the resulting boehmite was explored by thermogravimetry and differential thermal analysis. Accordingly, various calcination products of the boehmite were obtained at some selected temperatures in the range 400-1100°C and characterized by chemical analysis, X-ray powder diffractometry, and surface charge and specific area measurements. The results obtained indicated the synthesis of relatively high surface area transitional aluminas of industrial and catalytic merits.