Integration of a calcium carbonate crystallization process and membrane contactor–based CO2 capture

•Sustainable production of precipitated CaCO3 via CO2 capture by membrane contactor.•Demonstration of calcium carbonate crystallization as a by-product of CO2 capture.•Energy for CO2 decomposition is avoided by production of added-value chemical.•Aqueous solutions of sodium hydroxide for carbon capture and valorization. This research work presents the integration of polypropylene hollow fiber membrane contactor–based CO2 absorption unit using aqueous sodium hydroxide (NaOH) as the absorbent solution, and precipitation of high-quality calcium carbonate by addition of calcium chloride. The integrated crystallization process bypasses the need for cost-intensive energy regeneration of the absorbent solution. Given the lifetime of high added value precipitated calcium carbonate, the proposed approach for integrating solid particle formation and a carbon dioxide mitigation technique can be considered as a potential post-combustion technology for carbon capture, utilization and sequestration (CCUS). The overall CO2 mass transfer coefficient in the membrane contactor and subsequent crystallization process was investigated by conducting the experiments at different operating conditions. For a maximum hydroxide concentration of 5.01molL-1, an overall mass transfer coefficient of 2.25·10-4ms-1 and CO2 flux of 2.45·10-4molm-2s-1 were obtained for a 0.5Lmin-1 of gas flow rate. The proposed liquid–liquid crystallization process produces a narrow size distribution of micron-sized calcium carbonate with a mean diameter of 3–8 µm that can be used in the paper, coatings, food and biomedical industries.