Preparation And Mechanism Of Monodisperse Flaky Magnesium Hydroxide Hydrated

The preparation of magnesium hydroxide as function materials having wide application has some problems,such as high cost,long cycle,low purity and agglomeration.Monodisperse sheet magnesium hydroxide was hydrated for 2h using active magnesium oxide as raw materials.The products were characterized by BET,XRD,SEM and laser particle size analysis,and the kinetics model of hydration was established to explore the crystal growth mechanism.The effects of inorganic additives which made a theoretical foundation for the hydration on the morphology of magnesium hydroxide was studied.The effects of activity of magnesium oxide,external force,ultrasonic power,temperature and inorganic additives on properties of magnesium hydroxide were studied.The results showed the monodisperse sheet magnesium hydroxide crystals was hydrated by active magnesium oxide with specific area 4.5m²/g under ultrasonic power 450W at the temperature of 80℃.Combined with dissolution-precipipation mechanism,the morphology and phase change of products was analyzed dynamically,and the results showed that the hydration of Mg O was the heterogeneous nucleation process.Part of Mg²⁺adhered on the surface of magnesium oxide produced in situ growth of magnesium hydroxide,leading to the rate of the other the magnesia particles hydration was different,not in the same order.The hydration mechanism was:dissolution of magnesium oxide→diffusion of Mg²⁺ions→nucleation of growth elements→growth of growth elements→precipitation of magnesium hydroxide.Ultrasonic hydration at room pressure which has advantages of short reaction time,low cost and environment friendly controllable process is an effective way to realize the high value-added utilization of magnesium resources in China.Figure 57;Table 4;Reference 67.