The mechanisms and microstructures of passive atmospheric CO2 mineralisation with slag at ambient conditions

MacDonald, J. M. , Khudhur, F. W.K. , Carter, R., Plomer, B., Wilson, C. and Slaymark, C. (2023) The mechanisms and microstructures of passive atmospheric CO2 mineralisation with slag at ambient conditions. Applied Geochemistry, 152, 105649. (doi: 10.1016/j.apgeochem.2023.105649)

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Removal of CO2 already in the Earth's atmosphere through CO2 mineralisation with alkaline waste materials such as steel slag is one approach to mitigate the effects of anthropogenically-induced climate change. However, the microstructures produced during passive carbonation of slag are not well known. Here we use Scanning Electron Microscopy imaging and chemical mapping, X-Ray diffraction and stable isotopes (δ13C and δ18O) to show that ingassed and hydroxylated atmospheric CO2 reacts with Ca leached from slag to precipitate calcite directly on the slag surface. Precipitated calcite crystal morphologies vary, ranging from bladed and acicular crystals to layered deposits of micron-scale equant crystals. The variable morphology and extent of calcite precipitation documented is linked to a combination of internal (i.e. microstructural properties of the slag itself) and external (environmental conditions) factors. This work shows that atmospheric CO2 can be drawn down and mineralised passively by the slag at ambient conditions as part of the slag valorisation and reutilisation process.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Wilson, Dr Claire and Carter, Ms Ruth and MacDonald, Dr John and Khudhur, Faisal and Slaymark, Miss Charlotte
Authors: MacDonald, J. M., Khudhur, F. W.K., Carter, R., Plomer, B., Wilson, C., and Slaymark, C.
College/School:College of Science and Engineering > School of Chemistry
College of Science and Engineering > School of Geographical and Earth Sciences
Journal Name:Applied Geochemistry
ISSN (Online):1872-9134
Published Online:31 March 2023
Copyright Holders:Copyright © 2023 The Authors
First Published:First published in Applied Geochemistry 152: 105649
Publisher Policy:Reproduced under a Creative Commons License

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