A green synthesis strategy for low-cost multi-porous solid CO2 adsorbent using blast furnace slag

[Display omitted] •Abundant pore size hydrotalcite-like are synthesized using blast furnace slag.•The structure–performance relationship of BFS series adsorbents were studied.•BFS10.5-50TEPA sorbents show excellent CO2 adsorption performance.•The increased stacking porosity reduced CO2 mass transfer resistance.•The adsorption mechanism of BFS10.5-50TEPA is weak chemisorption and physisorption. The low-cost of CO2 adsorbent is crucial for realistic CO2 adsorption application. In this paper, a series of green CO2 adsorbents were prepared using tetraethylenepentamine (TEPA) functionalized blast furnace slag (BFS) as raw materials, which not only implemented the recycling of blast furnace slag solid waste, but also realized the low cost of amine adsorbents. A series of characterization analyses were performed on the synthesized hydrotalcite-like and hydrated calcium silicate green support materials. The effects of structures, TEPA loadings and adsorption temperatures on the material properties were investigated. The result shows that BFS10.5-50TEPA with more pores is an ideal adsorbent, its optimum adsorption capacity for CO2 is 5.64 mmol/g at 80 ℃, and the amine efficiency is as high as 38.42 %. According to CO2-TPD analysis, the dominant CO2 adsorption mechanism of BFS10.5-50TEPA were physisorption and weak chemisorption. Moreover, the adsorption kinetics and regeneration performances also studied. The results indicate that pseudo-first-order model and pseudo-second-order model are both not accurately at predicting experimental results, while the Avrami model can accurately predict the adsorption kinetics of CO2 at both low adsorption temperature and high adsorption temperature. After 10 adsorption-desorption recycles, the CO2 adsorption capacity of BFS10.5-50TEPA still maintain 5.02 mmol/g. This study provides a novel method for the preparation of solid amine adsorbents with high adsorption performance from low-cost solid waste.