Dynamic modeling and semibatch reactive crystallization of calcium carbonate through CO2 capture in highly alkaline water

Abstract

A laboratory scale integration of carbon capture and utilization (CCU) technique operating based on highly alkaline aqueous hydroxide sorbents with a semibatch reactive crystallization process of calcium carbonate is presented. The study was conducted with a focus on investigating the kinetics of the crystallization process for CCU applications, where the production of micron-sized calcium carbonate particles occurs by direct addition of CO2-loaded solution to a crystallizer containing calcium chloride. Within this system, the need for high temperature heat consumption above 800 °C (109.4 kJ/mol CO2) for CO2 decomposition from Na2CO3 is avoided by production of value-added chemical from carbonate reach solution. The current set-up enables potential pre-treatment of carbon emission sources due to separate absorption and liquid-liquid crystallization processes. This leads to production of high-purity solid particles in comparison to conventional industrial practices. Experiments were carried out at several operating conditions at ambient temperature and pressure and effect of the absorbent solution concentration on CO2 capture efficiency and subsequently the precipitation yield was analyzed. Based on coupling the standard method of moments approach of the population balance formulation with power-law kinetic expressions, a correlation was extracted between the growth rate constant and feed flow rate for the adopted process. Moreover, characterization of the precipitated sample indicates the vaterite polymorphs of calcium carbonate as the dominant crystals in the pH range of 7.9–10.4. These types of demonstrations could contribute to circular economy processes using waste materials and can be considered as a potential approach toward an efficient carbon capture and valorization technique.