In situ AFM investigation of heterogeneous nucleation and growth of sodium oxalate on industrial gibbsite surfaces in concentrated alkaline solution

Fu, Weng, Vaughan, James and Gillespie, Alistair (2015) In situ AFM investigation of heterogeneous nucleation and growth of sodium oxalate on industrial gibbsite surfaces in concentrated alkaline solution. Chemical Engineering Science, 126 399-405. doi:10.1016/j.ces.2014.12.057

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Author Fu, Weng
Vaughan, James
Gillespie, Alistair
Title In situ AFM investigation of heterogeneous nucleation and growth of sodium oxalate on industrial gibbsite surfaces in concentrated alkaline solution
Journal name Chemical Engineering Science   Check publisher's open access policy
ISSN 0009-2509
1873-4405
Publication date 2015-04-14
Year available 2014
Sub-type Article (original research)
DOI 10.1016/j.ces.2014.12.057
Open Access Status File (Author Post-print)
Volume 126
Start page 399
End page 405
Total pages 7
Place of publication Kidlington, Oxford, United Kingdom
Publisher Pergamon Press
Language eng
Subject 1500 Chemical Engineering
1600 Chemistry
2604 Applied Mathematics
2209 Industrial and Manufacturing Engineering
Formatted abstract
Highlights
• In situ AFM study of sodium oxalate nucleation and growth on gibbsite crystals.
• The lattice mismatches between gibbsite and sodium oxalate have been calculated.
• The epitaxial growth modes for sodium oxalate growth on gibbsite have been determined.

In situ atomic force microscopy (AFM) was used to study the nucleation behaviour of sodium oxalate on the gibbsite substrate in high ionic strength (5 M NaCl) and alkaline solution (pH=11.5). The growth of oxalate three-dimensional (3D) islands was observed on gibbsite (001) faces at medium oxalate supersaturation (σ=(Cinitial−Cequlibrium)/Cequlibrium=1.2). The 3D islands can be preferentially oriented with their (200) twin planes parallel to the gibbsite substrate (001) faces confirmed by both the calculation of lattice mismatch and AFM images. The lattice mismatch calculation also indicated that the most energetically favourable epitaxial relationship for oxalate growth on gibbsite is the growth of oxalate (200) planes on gibbsite (100) faces. In agreement with the prediction, the formation of heteroepitaxial layers of sodium oxalate on the gibbsite (100) faces were observed at high oxalate supersaturation (σ =1.4). The total strain energy ( γtotal ) in this oxalate layer was 6.62 mJ/m2 smaller than the interfacial tension of the gibbsite-solution interface ( γgs ) indicating that oxalate growth on gibbsite (100) faces is governed by Frank-van der Merwe growth mode. Meanwhile, oxalate 3D islands form on such heteroepitaxial layers, suggesting the Stranski–Krastanow mode for oxalate epitaxial growth.
Keyword Gibbsite
In situ AFM
Precipitation
Sodium oxalate
The Bayer process
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Available online: 29 December 2014.

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Chemical Engineering Publications
Official 2015 Collection
 
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