Carbonation experiment of basaltic crystals and glasses using supercritical CO2 under different PT conditions

Greenhouse gases, especially CO₂, have been increasing worldwide. To address this issue, carbon capture and storage (CCS) technology has been researched and developed to decrease atmospheric CO₂ concentrations. Among the various methods studied, mineral carbonation is an emerging technique that involves the reaction between Ca-Mg-Fe bearing basaltic rocks and CO₂ to store it in the rocks through the formation of carbonate minerals. The CarbFix project in Iceland is an example of this method. However, there is still much to learn about the physicochemical relationships between water, dissolved ions, and growing crystals in complex multicomponent systems at the atomic and nanoscale, which are essential for the successful implementation of CCS in basaltic reservoirs.

One of the methods being explored in this study involves the utilization of supercritical CO₂, which is achieved above the critical temperature and pressure of 30.97 °C and 73.773 bar, respectively. Under these conditions, CO₂ exhibits both liquid and gaseous properties. This work shows the results of an experiment conducted in basaltic crystals and basaltic glasses at the temperature and pressure range of 100 and 200 ºC, and 64 to 79 bar, to investigate the reaction between CO_2(sc), water, natural forsterite and basaltic glass, which have demonstrated that under these conditions we have the partial dissolution of the previous mineralogical phases, and the subsequent formation of new alteration phases, but also the precipitation of carbonates with Ca, Mg and Fe. We will compare our results with studies of carbonation of synthetic forsterite.