文献类型：期刊文献

英文题名：Insights into the polymorphic transformation mechanism of aluminum hydroxide during carbonation of potassium aluminate solution

作者：Jiang, You-Fa[1];Liu, Cheng-Lin[1];Xue, Jin[1];Li, Ping[1];Yu, Jian-Guo[1]

机构：[1]East China Univ Sci & Technol, State Key Lab Chem Engn, Natl Engn Res Ctr Integrated Utilizat Salt Lake R, Shanghai, Peoples R China

年份：2018

卷号：20

期号：10

起止页码：1431

外文期刊名：CRYSTENGCOMM

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000430582900012)】；

基金：The authors wish to acknowledge National Nature Science Foundation of China (Grant 51574126) for the financial support.

语种：英文

摘要：In this study, the carbonation process, in which potassium aluminate solution reacted with CO2/KHCO3 solution under different caustic concentrations (37.0 g K2Ok L-1, 92.5 g K2Ok L-1 and 222.0 g K2Ok L-1) and temperatures (40 degrees C and 80 degrees C), was investigated. The precipitation products were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Mastersizer. Bayerite was found to be present in the initial crystalline products, regardless of the temperature, caustic concentration and carbonation method and also, it was present as the predominant phase under most experimental conditions, which is fairly different from previous studies that reported the dependence on temperature or concentration. The transformation from bayerite to gibbsite was apparently promoted with an increase in temperature and caustic concentration. The polymorphic transformation during carbonation of potassium aluminate solution is discussed kinetically and structurally according to the calculated nucleation rate and is supposed to be: Al(III)-containing cluster -> boehmite -> bayerite -> gibbsite. The growth rate of bayerite was always several orders of magnitude higher than that of gibbsite, which led to the formation of the final products in a temperature- and caustic concentration- dependent manner. At a relatively high temperature and caustic concentration, the reaction was thermodynamically controlled and the most thermodynamically stable phase, namely gibbsite, was the predominant final product. However, at a low temperature and caustic concentration, the reaction was kinetically controlled and bayerite was the predominant product. It is concluded that the change in thermodynamic stability is not likely for bayerite and gibbsite in the present study. However, precise research on the possibility of the stability crossover between Al(OH)(3) polymorphs is worthy.