Effect of impurity ions on the primary nucleation of ammonium alum precipitated from aqueous solution

Ammonium alum is an important powder material for producing high purity alumina. It is usually obtained by crystallization from aqueous solution, but impurity ions in solution have a great effect on the quality of final product particles. Effects of sodium, potassium and iron ions on the primary nuc...

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Bibliographic Details
Published in:Powder technology 2021-02, Vol.379, p.217-222
Main Authors: Qu, Min, You, Shaowei, Liu, Pengfei
Format: Article
Language:English
Subjects:
Alum
Aluminum oxide
Ammonium
Aqueous solutions
Crystallization
Crystals
FBRM
Impurities
Induction time
Ion beams
Ions
Iron
Metastable zone width
Nucleation
Potassium
Primary nucleation
Sodium
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Summary:Ammonium alum is an important powder material for producing high purity alumina. It is usually obtained by crystallization from aqueous solution, but impurity ions in solution have a great effect on the quality of final product particles. Effects of sodium, potassium and iron ions on the primary nucleation of ammonium alum were studied by measuring induction time and metastable zone width using focused beam reflectance measurement (FBRM). It was found that potassium ion or iron ion enhanced the nucleation, whereas sodium ion had no obvious effect. Analysis about the mechanism of impurity incorporation showed that, due to the isomorphous substitution, potassium ion or iron ion were easily incorporated into ammonium alum crystals. Moreover, potassium ion was more easily incorporated into crystal than iron ion. [Display omitted] •Potassium and iron ions promote the nucleation of ammonium alum.•Sodium ion has no significant influence on the nucleation.•Isomorphous substitution leads to the incorporation of potassium and iron ions into crystals.•Potassium ion is more easily built into the crystal than iron ion
ISSN:0032-5910
1873-328X
DOI:10.1016/j.powtec.2020.10.072