CaO-based adsorbents derived from municipal solid waste incineration bottom ash for CO2 capture

The utilization of waste-derived adsorbents for CO2 capture presents a promising strategy for the reduction of adsorbent cost and waste volume. In this study, CaO-based adsorbent was prepared from Ca-rich municipal solid waste (MSW) incineration bottom ash (BA) as raw material. The effects of acid patterns, carbonization/calcination temperature, triblock copolymer (P123) and Mn loadings, as well as the steam contents in the flue gas on the cyclic CO2 capture capacity of the adsorbents were studied. The results showed that CaO-based adsorbents obtained by nitric- and acetic-acid extraction showed more stable adsorption capacity, due to more active CaO and less impurity content. When the Ca/Mn molar ratio was 100:1 and the concentration of P123 solution was 2 g/L, the prepared adsorbent showed the adsorption capacity of 0.321 g/g after 20 cycles, which was 175% of the unmodified CaO-based adsorbent (0.183 g/g). The addition of Mn and P123 increased the surface area and pore volume of the adsorbents, resulting in a dense distribution of pore size. Additionally, Mn could also inhibit the particle growth and mitigate sintering of the adsorbents. The electron transfer between Mn3+ and Mn4+ played a crucial role in generating labile oxygen vacancies, which improved the adsorption capacity of the adsorbents.