Shrinking Particle Reaction Model for a Waste Double-Base Propellant During Alkaline Hydrolysis

Double-base propellants are widely used in missiles and rocket engines. Waste double-base propellants must be safely disposed of because their safety and reliability greatly deteriorate during storage and use. Alkaline hydrolysis is a promising alternative to the open burning and open detonation disposal methods of waste propellants. To promote the industrialization of the alkaline hydrolysis treatment of waste double-base propellants, a reaction model of the alkaline hydrolysis of SC double-base propellants was studied. First, the relationship between the concentration of nitrite-nitrogen and nitrate-nitrogen in the alkaline hydrolysate was studied. The results revealed that a good linear relationship between the concentration of nitrite-nitrogen and nitrate-nitrogen (slope is 1.771, R² is 0.9925). The waste SC granules produce fewer nitrite ions than fresh nitrocellulose and nitroglycerin. Secondly, based on the analysis results of scanning electron microscopy, energy-dispersive X-ray spectroscopy, and the thickness of SC granules before and after alkaline hydrolysis, it was assumed that the reaction model was a shrinking particle reaction model, and the limiting step was the alkaline hydrolysis rate on the surface of granules. Then, the relationship between the alkaline hydrolysis degree x_SC of SC granules and reaction time t was x_SC=((α+2)/(2t_e))t-(α/(2t_e²))t² by theoretical reaction model derivation. Additionally, the reaction model and limiting step were experimentally validated. Thus, this study provides theoretical and technical support for the safe industrial deposal and resource utilization of waste SC and other double-base propellants with nitrocellulose and nitroglycerin as basic energetic components, as well as a basis for its fundamental research.