University of Oulu

Perumal, P., Hasnain, A., Luukkonen, T., Kinnunen, P., & Illikainen, M. (2021). Role of surfactants on the synthesis of impure kaolin-based alkali-activated, low-temperature porous ceramics. Open Ceramics, 6, 100097.

Role of surfactants on the synthesis of impure kaolin-based alkali-activated, low-temperature porous ceramics

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Author: Perumal, Priyadharshini1; Hasnain, Ali1; Luukkonen, Tero1;
Organizations: 1Faculty of Technology, Fibre and Particle Engineering Research Unit, PO Box 4300, University of Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 3.1 MB)
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Language: English
Published: Elsevier, 2021
Publish Date: 2021-09-03


Porous ceramics were generated by direct foaming the alkali-activated unprocessed kaolin (impure kaolin, iK) with the addition of hydrogen peroxide (H₂O₂) and calcining at a low temperature of 400 ​°C. Hydrogen peroxide, a blowing agent, decomposes producing oxygen gas bubbles forming the porous structure in the fresh alkali-activated iK paste. In the present study, three different molarity of alkali activator (5, 10, or 15 ​M NaOH) were employed. The dosage of blowing agent (H₂O₂) was varied between 0 and 2% with a constant dosage of 0.5% (wt. of binder) of surfactant. The gas bubbles in fresh-state geopolymer slurry are unstable with a tendency to coalesce. In such cases, surfactants are introduced to improve the stability of the gas-liquid interface. Two different surfactants: non-ionic and cationic ones were used to study the properties of alkali-activated porous material. Fresh properties such as viscosity, yield stress, foaming rate, and fresh density were compared between reference iK samples without surfactants and those with surfactants. The mechanical and microstructural properties of alkali-activated (AA) low-temperature porous iK ceramics were determined after calcination. Pore structures were characterized with electron microscope to understand the interaction of different parameters during fresh/hardened state and their relevance with the changes in the mechanical properties. Surfactants, irrespective of the type, highly influenced the fresh properties of the AA-iK samples, which in turn reflected on the compressive strength of the porous ceramics.

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Series: Open ceramics
ISSN: 2666-5395
ISSN-L: 2666-5395
Volume: 6
Article number: 100097
DOI: 10.1016/j.oceram.2021.100097
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
215 Chemical engineering
Funding: The authors gratefully acknowledge the financial support received from the project GEOMINS [grant #319676: Steps towards the use of mine tailings in geopolymer materials: reactivity, CO2 sequestration and heavy metal stabilization], CERATAIL [grant #292526: Novel synthesis methods for porous ceramic from mine tailings], Functional geopolymers and peracids in disinfection and advanced oxidation of water and wastewater [grant #315103] funded by Academy of Finland, and Academy of Finland InStreams profiling (grant #326291). P.P. gratefully acknowledges the financial support received from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska Curie grant agreement No [839848].
EU Grant Number: (839848) W2W - Waste to Wealth (W2W): A total solution for municipal solid waste incinerated ash in geopolymer concrete
Academy of Finland Grant Number: 319676
Detailed Information: 319676 (Academy of Finland Funding decision)
292526 (Academy of Finland Funding decision)
315103 (Academy of Finland Funding decision)
326291 (Academy of Finland Funding decision)
Copyright information: © 2021 The Author(s). Published by Elsevier Ltd on behalf of European Ceramic Society. This is an open access article under the CC BY-NC-ND license (