Advancements in enforced C2S wet carbonation: Leveraging δ13C isotope tracking for reaction insights

This study concerns wet carbonation of β-C₂S (Ca₂SiO₄) in a closed system at 23 °C. The progress of carbonation was detected by quantitative X-ray diffraction (QXRD) and thermogravimetric analysis (TGA). Further measurements of pH and ion concentrations as well as modelling carbon species and saturation indices were done. Additionally, stable carbon isotope ratios (δ¹³C) in CO₂, dissolved inorganic carbon (DIC) and carbonate phases were measured. The aim of this study was to investigate δ¹³C isotope values during C₂S carbonation. If a systematic fractionation of carbon isotopes occurs during the reaction, it can help to quantify the carbonation reaction. During the carbonation process over 48 h, we found carbon isotope distributions from the gaseous phase to the solution and ultimately to the solid phase. Calculations confirm the direct relation of δ¹³C values to the carbonation progress. With this, stable isotope measurements offer a promising tool to monitor the reaction progress in-situ.