University of Oulu

Yangmei Yu, Priyadharshini Perumal, Ian J. Corfe, Tirthankar Paul, Mirja Illikainen, Tero Luukkonen, Combined granulation–alkali activation–direct foaming process: A novel route to porous geopolymer granules with enhanced adsorption properties, Materials & Design, Volume 227, 2023, 111781, ISSN 0264-1275,

Combined granulation–alkali activation–direct foaming process : a novel route to porous geopolymer granules with enhanced adsorption properties

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Author: Yu, Yangmei1; Perumal, Priyadharshini1; Corfe, Ian J.2;
Organizations: 1Fibre and Particle Engineering Research Unit, University of Oulu, Finland
2Geological Survey of Finland, GTK, 02150 Espoo, Finland
3Biomimetics and Intelligent Systems Group, University of Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 3.7 MB)
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Language: English
Published: Elsevier, 2023
Publish Date: 2023-10-02


High-value applications, such as adsorbents, have drawn attention to geopolymers. In several of those applications, having the geopolymer as porous spherical particles is beneficial. This study presents a novel process for fabricating porous metakaolin-based geopolymer granules using a combination of direct foaming, one-part alkali activation, and granulation. In short, the precursor (e.g., metakaolin) and solid activator (e.g., sodium silicate) are loaded in a granulator, in which an aqueous blowing agent (e.g., H₂O₂) is added while the granulator is running, and the obtained granules are cured at 60 °C. Characterization of the granules for physico-chemical and morphological properties indicated an increase in overall porosity, especially in the µm-scale pores. Also specific surface area (+50%) and nanoscale pore volume (+102%) increased when using more concentrated H₂O₂ (20 or 30%) compared to nonporous granules. The use of porous granules was also demonstrated in dynamic adsorption experiments for ammonium (NH₄⁺) uptake, which showed up to ∼126% increase in cumulative adsorption amount compared to nonporous granules. The highest NH₄⁺ uptake was obtained with 10% H₂O₂ solution as the granulation fluid. The results confirmed the feasibility of the method for introducing porosity to geopolymer granules, which enhances the adsorption properties of the granules.

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Series: Materials & design
ISSN: 0264-1275
ISSN-E: 1873-4197
ISSN-L: 0264-1275
Volume: 227
Article number: 111781
DOI: 10.1016/j.matdes.2023.111781
Type of Publication: A1 Journal article – refereed
Field of Science: 116 Chemical sciences
215 Chemical engineering
216 Materials engineering
218 Environmental engineering
Funding: This work was financially supported by the Business Finland (project TYPKI, grant ID 43643/31/2020) and the University of Oulu & the Academy of Finland Profi5 (grant ID 326291). Part of the work was carried out with the support of the Centre for Material Analysis, University of Oulu, Finland.
Copyright information: © 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (