Eco-friendly, sustainable and porous eggshell/tea waste-derived CaO nanoparticles as a high-temperature CO2 sorbent: Fabrication and textural/morphological evaluation

Abstract

The CaO-based sorbents suffer from a high-intensity sintering rate and require costly promoters to improve their CO2 capture capacity through the Calcium Looping (CaL) technique. Herein, for the first time, the eco-friendly and efficient eggshell-derived CaO sorbents were promoted with tea waste for the CO2 capture process. 0, 2.5, and 5 wt.% of ball-milled tea waste nanoparticles (NPs) were merged with sieved eggshell-based NPs throughly. Their CO2 capture activity was evaluated under severe calcination conditions, including calcination under 100 vol.% CO2 for 5 min at 950 °C. According to the textural/morphological data, 92 % and 89.8 % enhancement were seen for the prepared sample's surface area and pore volume, including 5 wt.% tea waste NPs. Additionally, the average grain size of as-prepared specimens decreased from 39.3 nm to 25.2 nm. Furthermore, the sorbent having 5 wt.% tea waste presented the multicyclic durability of 48.1 % and the average CO2 uptake capacity of 0.133 g CO2/g sorbent during fifteen multiple carbonation/calcination cycles under severe calcination conditions. The incorporation of 5 wt.% tea waste as the structural promoter resulted in 100 % and 58 % improvements in the capture potential of CaO at kinetically- and diffusion-controlled carbonation stages of the 15th cycle.