Performance evaluation and environment risk assessment of steel slag enhancement for seawater to capture CO2

Abstract

Major CO2 emitters are concentrated in coastal areas of China. The seawater with potential to capture CO2 was used as an absorbent and the addition of steel slag (SS) enhanced CO2 absorption by seawater. CO2 solubility in steel-slag-enhanced seawater was measured by an on-line chromatography apparatus, and the characterization analysis, thermodynamics, and kinetics were researched. CO2 solubility in seawater with a steel slag of 1.00 wt% increases by 64.27% relative to that in seawater, but is smaller than that in simulated-steel-slag-seawater (increasing by 29.86% relative to that in seawater with real steel slag). The results of XRD, TGA, IR and SEM-EDS show that Ca(OH)2 in the steel slag reacts with CO2 to form CaCO3. More quantity of CaO in simulated steel slag reacted with CO2 compared to real steel slag from XRF analysis. Increasing the concentration of steel slag and decreasing particle size of steel slag can also improve CO2 solubility and CO2 absorption rate. The steel slag and products after capturing CO2 are not hazardous waste and the steel slag can operate the solidification/stabilization of toxic metals. Steel slag can enhance CO2 absorption by seawater and perennially segregate CO2, providing CO2 capture and storage for coastal zones.