Understanding CO2 adsorption in layered double oxides synthesized by slag through kinetic and modelling techniques

As main by-product in iron and steel industry, high value-added utilization of blast furnace slag had received extensive attention. In this paper, a novelty technology was proposed for using blast furnace slag as raw material to obtain excellent CO2 adsorbent-layered double oxides. The characteristics of layered double hydroxides and layered double oxides were investigated in detailed. Most notably, the laminate structure of layered double hydroxides collapsed and the pore structure, particle size distribution and functional groups of the sample had been greatly changed. The layered double oxides were occupied by phases of CaO, Ca12Al14O32Cl2 and MgO. The transformation mechanism of the layered double oxides preparation was obtained. In addition, CO2 concentration and temperature influencing on CO2 adsorption of layered double oxides were studied and established a suitable kinetic model. The optimal kinetic mechanism model of CO2 adsorption by layered double oxides was PSO. The activation energy and pre-exponential factors were 56.88 kJ‧mol-1 and 12.26 min-1, respectively. Ultimately, CO2 adsorption capacity comparison and preliminary economic evaluation were conducted to assess the industrial feasibility of this technology. This work achieved the goals between CO2 reduction and high value-added utilization of solid waste in iron and steel industry.