A Comparative Study of Mineral Carbonation Using Seawater for CO2 Utilization: Magnesium-Based System Versus Calcium-Based System with Low Energy Input

Abstract

Mineral carbonation is promising for CO2 utilization and sequestration via capturing CO2 into stable solid carbonates. However, the effectiveness and price of the solvents, as well as the energy consumption of CO2 purification and pressurization of industrial flue gas, are hindering the development of this technology. Therefore, this study integrates two important concepts of seawater utilization and direct use of CO2 gas without purification and pressurization, investigating the mineral carbonation using seawater as an alternative solvent with low energy input. Carbonation of magnesium- and calcium-based systems is investigated, and the behaviors as well as mechanisms of using seawater and distilled water are compared. The kinetics, conversion progress of compounds, and carbonation behavior are determined. The CO2 uptake capacities of seawater carbonation are higher in the Mg-based system (1.16 g-CO2/g-MgO) than in the Ca-based system (0.68 g-CO2/g-CaO); however, most CO2 in the Mg-based system is captured in the solution phase. Insights into reaction optimization are provided. The potential assessment of mineral carbonation using seawater is provided. This study aims to facilitate the development of CO2 utilization and provide opportunities for mineral carbonation using seawater, through applying various alkaline wastes containing Ca and Mg from diverse industries.