University of Oulu

Luukkonen, T., Tolonen, ET., Runtti, H. et al. J Mater Sci (2017) 52: 9363.

Optimization of the metakaolin geopolymer preparation for maximized ammonium adsorption capacity

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Author: Luukkonen, Tero1; Tolonen, Emma-Tuulia1,2; Runtti, Hanna2;
Organizations: 1Kajaani University of Applied Sciences, P.O. Box 52, 87101 Kajaani, Finland
2Research Unit of Sustainable Chemistry, University of Oulu, P.O. Box 3000, 90014 Oulu, Finland
3Kajaani University of Applied Sciences, Kajaani, Finland
4Kokkola University Consortium Chydenius, University of Jyvaskyla, P.O. Box 567, 67701 Kokkola, Finland
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 1.1 MB)
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Language: English
Published: Springer Nature, 2017
Publish Date: 2018-05-05


Geopolymers are functional materials that can be used in various environmental applications such as adsorbents in pollutant removal from wastewaters. Metakaolin geopolymer (MK-GP) has been proven to be especially suitable for ammonium (NH₄⁺) removal. In this research, the optimal reagent and raw material ratios in the preparation of MK-GP in terms of NH₄⁺ adsorption capacity were investigated. The response surface methodology based on the face-centered central composite design was used to optimize the levels of three factors: the amounts of hydroxide, silicate, and metakaolin. In addition, the effect of Na or K as the charge-balancing cation was studied. Empirical models were fitted to the experimental data using multiple linear regression. The significance of the models was confirmed by means of analysis of variance. Optimal NH₄⁺ removal efficiency was achieved when the amounts of hydroxide and silicate were maximized, the amount of metakaolin was minimized, and Na-based reagents were used. These trends are most likely a result of optimized conversion of metakaolin into MK-GP.

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Series: Journal of materials science
ISSN: 0022-2461
ISSN-E: 1573-4803
ISSN-L: 0022-2461
Volume: 52
Issue: 16
Pages: 9363 - 9376
DOI: 10.1007/s10853-017-1156-9
Type of Publication: A1 Journal article – refereed
Field of Science: 116 Chemical sciences
216 Materials engineering
218 Environmental engineering
Funding: This work was supported by the Finnish Funding Agency for Innovation (TEKES) [Grant Number 4096/31/2014, project GeoSorbents].
Copyright information: © Springer Science+Business Media New York 2017. This is a post-peer-review, pre-copyedit version of an article published in Journal of Materials Science. The final authenticated version is available online at: