Comparing methods for determining the CO$_2$ content in CO$_2$-sequestering materials and natural rock

Kavčič, Nika (author), Tominc, Sara (author), Žibret, Lea (author), Žibret, Gorazd (author), Kolar, Mitja (author), Ducman, Vilma (author)

Carbon capture plays an important role in the decarbonation of the building sector. One way to capture carbon is through mineral carbonation, in which Ca and Mg compounds react with CO$_2$ to form stable carbonate minerals such as calcite, dolomite, magnesite and/or siderite, permanently sequestering CO$_2$. Various techniques are available to measure the amount of permanently bound CO$_2$ and quantify the carbonation potential. The suitability and accuracy of a particular method are very important, as the accurate determination of CO$_2$ is crucial to correctly assess the sequestration potential of different materials. This study compares the three methods: calcimetric, gravimetric and thermogravimetric analysis used for CO$_2$ determination in different types of ash, slag and natural rock. While the CO$_2$ content in natural rock is stable, the CO$_2$ content in slag and ash can change over time as the contained minerals gradually absorb CO$_2$ (by natural or accelerated carbonation) until they are fully carbonated. To avoid errors in testing the CO$_2$ uptake, as-received samples were first exposed to the full carbonation process and then tested. The comparison of calcimeter, thermogravimetric and gravimetric analysis of ground and sieved samples with a particle size below 125 μm shows that the results usually differ by less than 2 %. Higher deviations could be caused by non-carbonate minerals (especially in slags) that can react with hydrochloric acid during the calcimetric and gravimetric tests and/or decompose in the range where carbonates decompose, contributing to inaccurate CO$_2$ measurements. The measurement uncertainty was calculated for all three quantitative methods to allow a practical comparability.

• Language: English
• Keywords: CO$_2$ sequestration, ash, slags, natural rocks, TGA, calcimetry, measurement uncertainty
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Publication status: Published
• Publication version: Version of Record
• Year: 2025
• Number of pages: Str. 43786-43795
• Numbering: Vol. 51, iss. 25, pt. A
• PID: 20.500.12556/RUL-182552
• UDC: 54
• ISSN on article: 1873-3956
• DOI: 10.1016/j.ceramint.2025.07.109
• COBISS.SI-ID: 242372099
• Publication date in RUL: 15.05.2026

Record is a part of a journal

• Title: Ceramics international
• Publisher: Elsevier
• ISSN: 1873-3956
• COBISS.SI-ID: 23209733

Licences

• License: CC BY-NC 4.0, Creative Commons Attribution-NonCommercial 4.0 International
• Link: http://creativecommons.org/licenses/by-nc/4.0/
• Description: A creative commons license that bans commercial use, but the users don’t have to license their derivative works on the same terms.

Secondary language

• Language: Slovenian
• Keywords: privzem CO$_2$, pepel, žlindra, naravni kamen, TGA, kalcimetrija, merilna negotovost

Projects

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: J1-50032
• Name: Geološka in litogeokemijska karakterizacija slovenskih Dolomitov s poskusno ekstrakcijo magnezija

• Funder: EC - European Commission
• Funding programme: HE
• Project number: 101058162
• Name: Integration of Underutilized Ashes into Material Cycles by Industry-Urban Symbiosis
• Acronym: AshCycle