Modelling and optimization of carbon dioxide sequestration potential of carbide slag waste

Mineral carbonation (MC) of industrial wastes has gained significant attention as a promising approach for reducing carbon dioxide (CO₂) emissions. This study investigates the wet-phase MC of carbide slag waste at realistic conditions for CO₂ capture and storage. Response Surface Methodology with a central-composite design was employed for optimization and modeling for wet-phase MC of carbide slag waste. Five operational parameters namely temperature, pressure, relative humidity, liquid-to-solid (L/S) ratio, and CO₂ loading rate were analyzed for their individual and interactive effects on CO₂ capture capacity and the reaction kinetics. Further, quadratic models were developed to predict CO₂ capture capacity and time required for 50 % carbonation conversion (time₅₀). The results revealed that the most influential factor was pressure followed by the L/S ratio for CO₂ capture capacity. While time₅₀ was majorly influenced by the CO₂ loading rate and pressure. The quadratic models for CO₂ capture capacity and time₅₀ have an R² value of 0.9863 and 0.9986, respectively. Moreover, the results predicted from the models for both responses were closely aligned with the experimental results. The optimized conditions yielded a maximum CO₂ capture capacity of 11.9 mol kg⁻¹ at 10 bar pressure, 65 °C, in the presence of 0.2 L/S ratio and 75 % relative humidity in 121 minutes, where 50 % conversion occurs in the first 52 minutes. In conclusion, wet-phase MC of carbide slag represents a promising approach to address both industrial waste utilization and CO₂ reduction. The high CO₂ capture capacity achieved under various experimental conditions demonstrates carbide slag as a viable candidate for large-scale CO₂ capture applications. Furthermore, techno-economic analysis and scalability assessments will be crucial in advancing this approach to industrial relevance.