Carbonatation of Sulphates for CO2 sequestration

Project Information

CARS-CO2

Grant agreement ID: 101021894

DOI

10.3030/101021894

Project closed

EC signature date 6 April 2021

Start date 1 February 2022

End date 31 January 2024

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 184 707,84

EU contribution

€ 184 707,84

Coordinated by

UNIVERSITE GRENOBLE ALPES
France

Periodic Reporting for period 1 - CARS-CO2 (Carbonatation of Sulphates for CO2 sequestration)

Reporting period: 2022-02-01 to 2024-01-31

Summary of the context and overall objectives of the project

Calcium sulfates are abundant minerals in the earth's crust. These minerals, which are slightly soluble in water, can be transformed into carbonates when they come into contact with water containing this compound. The main goal of CARS-CO2 was to leverage these reactions as a method for capturing and storing CO2, one of the primary greenhouse gases responsible for the current accelerated climate change.
The project had the following three objectives:
1. Improving our understanding of the crystallization processes of sulphates and carbonates.
2. Studying the mechanisms, kinetics and stability of the carbonatation of sulphates and the evaluation of sulphates as potential “sequestrators” of CO2.
3. Designing an effective strategy to use carbonatation of natural and waste sulphates to capture CO2.
The achievement of the third objective depended on the successful completion of the first two, making it the cornerstone of the project with the most significant societal impact. Leveraging insights gained from the initial objectives, a novel CO2 capture method was developed. This method utilizes powdered gypsum (CaSO4·2H2O) combined with carbonate solutions derived from CO2 capture. Mixing the powdered gypsum with these solutions yields a new carbonate mineral phase, namely vaterite (CaCO3), and sulfate-rich solutions, all achievable at ambient temperatures. Both resulting by-products hold industrial significance; vaterite finds applications in various sectors like cosmetics and pharmaceuticals, while the sulfate-rich solutions could be repurposed for synthesizing new gypsum or for agricultural fertilization. Consequently, the proposed approach aligns with the principles of the circular economy, wherein waste materials are converted into resources with renewed utility.
Furthermore, this project also provides a proof of concept for future endeavors, wherein waste gypsum produced by diverse industries would replace synthetic and natural gypsum, thereby extending the sustainability of the approach.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

During this project, we managed to obtain a series of very interesting results on the nucleation and growth of sulphates, as well as on the transformation of sulphates into carbonates.
In this project, atomic force microscopy has been used to study the growth of gypsum on its main faces. We have been able to observe, for the first time, that the different faces have different growth mechanisms. A manuscript describing these results has been submitted for review to the journal Geochimica et Cosmochimica Acta.
The transformation of gypsum to bassanite in solutions with a high salt concentration, as well as the reverse reaction, i.e. the transformation of bassanite to gypsum, have also been studied using in situ Raman. These results, combined with results obtained in synchrotron experiments, have been published in the Journal of Cleaner Production.
Currently, we are finishing a third manuscript dealing with the transformation of gypsum into vaterite (a type of calcium carbonate used in different industries). This study, in which we have combined measurements made using an in situ Raman with measurements made ex situ, we have proposed a method of sulphate carbonation in which we use as raw material synthetic or natural gypsum and carbonate solutions, which were obtained by CO2 capture. This method therefore allows to capture CO2 and, at the same time, to obtain value-added by-products (i.e. vaterite and sulphate solutions).
During this period, additional side projects have focused on foliar fertilisation research, exploring various compounds pertinent to the project, such as sulphate solutions and carbonate particles. These efforts have resulted in remarkable findings that have been disseminated through publications in different journals.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Thanks to the findings gleaned over two years of dedicated research, our project has successfully unlocked an intriguing avenue for sulfate carbonation under ambient conditions in which it is possible to control the calcium carbonate phase obtained (i.e. vaterite or calcite). In this innovative approach, we have leveraged both synthetic and natural gypsum in tandem with carbonate solutions. These solutions, derived from CO2 capture, underscore the potential of our method in addressing the urgent need to mitigate this greenhouse gas, a primary driver of climate change.
Beyond its environmental benefits, this sulfate carbonation pathway yields materials of significant economic value. Vaterite, as a solid phase, holds promise across diverse industrial sectors such as cosmetics and pharmaceuticals, while sulfate-rich solutions offer avenues for gypsum resynthesis or serve as potent foliar fertilizers for agricultural cultivation. Thus, our method not only facilitates CO2 capture but also aligns with principles of circular economy by repurposing waste streams into valuable resources.
By showcasing the viability of our approach, this project sets the stage for future endeavours. We envision utilizing waste gypsum from various industries to bolster CO2 capture efforts, effectively addressing two environmental challenges while simultaneously generating industrial-grade by-products.

Scheme of the proposed processes for the obtention of vaterite