Elucidation of Potable Water Accelerated Weathering of Limestone for Post-Combustion Carbon Capture: Correlation, Optimization, Comparative, Kinetic Modelling and Mass Transfer Analysis

Abstract

Energy generation and industrial processes are the main emitters of CO₂, with 37.4 billion tCO₂ in 2023, causing detrimental environmental effects. As absorption is the most established carbon capture technology, this research implements the accelerated weathering of limestone (AWL) process to capture CO₂ from post-combustion emissions. However, this work replaces the conventional water source for the AWL process, seawater, with potable water. A correlation study was performed to study the effect of the proposed process's liquid-to-gas (L/G) ratio on the performance (i.e., effluent's alkalinity and CO₂ capture efficiency). The correlation findings show that by decreasing the L/G ratio (1–0.003), the calcium bicarbonate (Ca(HCO₃)₂) effluent concentration (0.77–3.65 mM) and pH (5.58–7.47) increase significantly, whereas CO₂ capture efficiency (81.94%–20.82%) was adversely affected. The optimization analysis obtained the highest achievable alkalinity at 3.63 mM at an optimized liquid and gas flow rate of 0.024 and 10 L min⁻¹, respectively. Meanwhile, the liquid and gas flow rates of 1.23 and 1 L min⁻¹ achieved the highest CO₂ capture efficiency of 82.15%. It was deduced that potable water is better than seawater for CO₂ capture operation via the AWL process, achieving a 12.09%–39.14% better CO₂ capture efficiency when operated at similar conditions. In addition, the kinetic and mass transfer performance of the proposed process was also established in this work. Overall, this research establishes the potential of a potable water-operated AWL process for future commercialization.