Production of colloidally stable calcium carbonate precipitates to enhance CO2 subsurface storage through mineralization
Isah Mohammed, Mohamed Mahmoud, Dhafer Al Shehri, Abdulwahab Muhammad Bello
Abstract
Around the world, a lot of conversations centre on the pursuit of carbon sequestration and storage. The goal is to create solutions that minimize atmospheric emissions while guaranteeing storage security. In light of this, mineral and solubility trapping are seen to be the safest among the numerous potential alternatives. Aquifers and depleted oil and gas reservoirs are just two of the many possible storage locations for solubility trapping that exist worldwide. However, all brines have a maximum solubility limit that once reached, no further CO 2 can be dissolved, thus, its limitation. On the other hand, because CO 2 is transformed into solids and stored in that state in the case of mineral trapping, it is deemed the safest long-term storage option. But according to recent research, it takes a long time—roughly two years—to complete. Thus, the mineralization of CO 2 in a CaCl 2 -rich solution is shown for the first time to be accomplished in 24 h. This study's technique included using a chelating agent to achieve mineralization and looking at the effects of pressure, temperature, and chelating agent concentration on the process. The findings of this investigation demonstrated that, in the presence of a chelating agent, calcite precipitation can occur from the interaction of CO 2 with a CaCl 2 -rich solution in less than a day. The chelating agent's dehydration of the cations (Ca 2+ ) to speed up their interaction with the carbonate ion in the solution is the mechanism causing the notable improvement in the mineralization kinetic observed here. Mineralization, which is normally assumed to take a long time, can be accomplished in a day by following this easy procedure. Further investigation was conducted on the precipitates' bulk and mineralogical composition . Additionally, a scanning electron microscope was utilized to identify the five unique crystal forms that were created in the precipitated calcite . The results of this study are also regarded as revolutionary since they have far-reaching consequences for our efforts to store CO 2 in the safest possible way. Furthermore, reject water from a water treatment procedure like reverse osmosis might be the feed stream for the process this study describes. Consequently, wastewater can be turned into wealth and help achieve sustainability objectives.