Carbonate quantification in co₂ removal technologies through lime carbonation: experimental comparison of analytical techniques

The increase in anthropogenic carbon dioxide emissions has driven the development of carbon removal technologies capable of reducing atmospheric CO₂ concentrations and contributing to global climate targets. Among these alternatives, direct air capture through lime carbonation represents a promising approach due to its ability to transform atmospheric CO₂ into stable calcium carbonate through chemical reactions with alkaline materials. In this context, the accurate quantification of carbonate content constitutes a fundamental element for monitoring, reporting, and verification processes associated with carbon capture and storage systems. The objective of this research was to comparatively evaluate different analytical techniques for determining calcium carbonate content in materials representative of lime carbonation DAC systems. A quantitative experimental approach was applied using synthetic samples composed of different proportions of Ca(OH)₂ and CaCO₃. The evaluated techniques included volumetric calcimetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, and combustion with infrared detection. The results showed that thermogravimetric analysis and infrared combustion presented higher precision and reproducibility, while FTIR and calcimetry demonstrated advantages related to rapid analysis and lower operational costs. Furthermore, the study identified that mineralogical composition significantly influences the accuracy of analytical measurements. This research provides relevant information for the development of standardized protocols applicable to monitoring and verification systems in carbon dioxide removal technologies.