Enhancement mechanisms of spherical UFA on CO2 capture of waste slag

At present, the rising level of carbon dioxide (CO2) in the atmosphere has become a global concern, which urges researchers to find possible solutions to reduce or capture CO2 emissions. Mineralization is an important method for reducing CO2 emissions. In this study, the investigation provided an important opportunity to advance the understanding of the improving mechanism of spherical ultrafine fly ash (UFA) on the CO2 mineralization of waste slag (WS). The results show that adding UFA could significantly improve the mineralization efficiency (E), with an increased rate was 25.04%. UFA can effectively reduce CaCO3 covered on the surface of WS, resulting in more Ca2+, OH could be released from WS. XRD, FTIR, TG, and SEM-EDS analysis revealed the surface of the UFA powder serves as another ideal ectopic growth matrix for the production of CaCO3. A mechanism model of UFA improving WS mineralization was proposed.