An Experimental Study of Phase Transformations of Aluminum Oxides in the Processes of Sub- and Supercritical Water Oxidation of Metallic Aluminum

In this work, samples of metallic aluminum are objects of sub- and supercritical water oxidation. Experimental studies have been carried out, and dependences of the effect of temperature, pressure, reaction time, and pH of the oxidizing agent on the phase composition of the oxidation products and their adsorption properties have been revealed. Experimental studies have been carried out in the temperature range of 275–380°C, reaction time from 3 to 12 h, and different water pH of 7–12. Maximum specific surface S = 120.2 m2/g samples obtained at temperature T = 380°C and reaction time τ = 3 h with pH 12. The phase composition of this sample included aluminum oxide γ-Al2O3 (92.3 wt %) and corundum α-Al2O3 (7.7 wt %).