Optimization of AlN hydrolysis in aluminum dross based on response surface methodology and reaction kinetics

Aluminum nitride (AlN) in aluminum dross could be hydrolyzed in humid air, releasing a large amount of NH 3 . NH 3 can harm environment and human health when exposed to air, but it could be recycled and utilized after effective disposal. This paper studied the effects of reaction temperature, liquid-solid ratio, and time on hydrolysis behavior, and optimized experimental conditions using response surface methodology, in response to characteristics of long reaction time and incomplete reaction in AlN hydrolysis. Hydrolysis rate of AlN was 92.45% under the optimum experimental conditions of: reaction temperature of 95 °C, reaction time of 11.2 h, liquid-solid ratio of 7.8: 1 mL/g, and stirring speed of 400 r/min. Reaction kinetics studies showed that hydrolysis process was controlled by a surface chemical reaction control model with an apparent activation energy of 40.24 kJ/mol. XRD and SEM-EDS results showed that AlN transforms into Al(OH) 3 adhering to the surface of aluminum dross, with the crystals growing over temperature and time. This work provided value for recycling of NH 3 from aluminum dross.