Polymorphic Transformation of Aluminum Hydroxide Precipitated from Reactive NaAl(OH)4鈭扤aHCO3 Solution
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- 作者：Yan Li ; Yifei Zhang ; Fangfang Chen ; Chao Yang ; Yi Zhang
- 刊名：Crystal Growth & Design
- 出版年：2011
- 出版时间：April 6, 2011
- 年：2011
- 卷：11
- 期：4
- 页码：1208-1214
- 全文大小：934K
- 年卷期：v.11,no.4(April 6, 2011)
- ISSN：1528-7505
文摘
For the first time, the polymorphism and nucleation mechanism of the precipitates from concentrated sodium aluminate solution reacted with sodium bicarbonate solution were investigated. The interface tensions of gibbsite and bayerite in the solution were measured as 45.9 and 58.3 mJ/m2, respectively. Temperature and supersaturation significantly affected the polymorph as well as the polymorphic transformation of the initial precipitates in the reactive solution. Gibbsite solely nucleated at 70 掳C, while bayerite solely nucleated at 50 掳C regardless of supersaturation; however, the high supersaturation benefited the nucleation of bayerite and inversely the nucleation of gibbsite at 60 掳C. The sequence of polymorphic transformation in the reactive solution was proposed as Al-containing cluster 鈫?boehmite 鈫?bayerite 鈫?gibbsite. And the transformation rate from bayerite to gibbsite in the mother solution increased with temperature and caustic concentration.