CO2 capture and revalorization as carbonate crystals using membrane technologies

Climate change is clearly an urgent challenge nowadays. The constant accumulation of greenhouse gases and their drastic consequences have led to intensified research aiming to reduce the impact of human activities on the environment. As carbon dioxide (CO2) is the primary greenhouse gas emitted through human activities, numerous projects focus on the reduction of CO2 emissions. Carbon capture and storage are considered, but this strategy considers carbon dioxide as a waste. Carbon capture and utilization, on the other hand, gives a sustainable answer by giving value to the carbon by transforming it into another reusable product. Several revalorization routes are being explored, and mineralization (crystallization) seems to be an efficient methodology as it is thermodynamically favorable. Several carbonate compounds can be produced and marketed. Sodium bicarbonate (NaHCO3) is an interesting candidate as it can be used for numerous applications in the chemical, food, pharmaceutical, and textile industries. Such a carbon capture and revalorization process is currently under development in our group in UCLouvain. The process makes use of membrane technologies to capture and convert carbon dioxide into sodium bicarbonate as a final product. The process is divided into two steps: first, the CO2 is captured in a membrane base absorption process using a solvent promoted by enzymes or amino acids. Then, the resulting solution is concentrated up to crystallization in a membrane contactor. The different promoted solvents and routes for crystallization are being optimized. [1-4] The results are the following: In the first step (absorption), the CO2 absorption efficiency was evaluated, observing the enhancement of the mass transfer when enzymes or amino acid salts were used. In the second step (crystallization), we were able to obtain crystals with high purity. The morphology of the crystals is shown in Figure 1. Ongoing research is focusing on the study of the presence of other