Environmental Benign Synthesis of Lithium Silicates and Mg-Al Layered Double Hydroxide from Vermiculite Mineral for CO₂ Capture

This research introduces a completely new environmental benign synthesis route for obtaining two kinds of inter-mediate and high temperature CO₂ sorbents, Mg-Al layered double hydroxide (LDH) and Li₄SiO₄, from vermiculite. The mineral vermiculite was leached with acid, from which the obtained SiO2 was used for the synthesis of Li₄SiO₄ and the leaching waste water was used for the synthesis of Mg-Al LDH. Therefore, no waste was produced during the whole process. Both Li₄SiO₄ and Mg-Al LDH sorbents were carefully characterized using XRD, SEM, and BET analyses. The CO₂ capturing performance of these two sorbents was comprehensively evaluated. The influence of the Li/Si ratio, calcination temperature, calcination time, and sorption temperature on the CO₂ sorption capacity of Li₄SiO₄, and the sorption temperature on the CO2 sorption capacity of LDH, were investigated. The optimal leaching acid concentration for vermiculite and the CO₂ sorption/desorption cycling performance of both the Li₄SiO₄ and Mg-Al LDH sorbents were determined. In sum, this demonstrated a unique and environment-friendly scheme for obtaining two CO₂ sorbents from cheap raw materials, and this idea is applicable to the efficient utilization of other minerals. View Full-Text