Wastes against wastes treatment: Industrial silica fume derived porous solid amine adsorbent for efficient and reversible ultralow-pressure CO2 adsorption

The utilization of ambient low-pressure CO 2 adsorption for carbon neutrality initiatives holds great potential. However, conventional liquid amine absorption methods for CO 2 capture are plagued by high energy consumption and equipment corrosion issues. In this study, we present a novel approach using industrial waste silica fume (SF) as a precursor and tetraethylenepentamine (TEPA) as a chemical modifying agent to efficiently synthesize low-cost mesoporous solid amine adsorbents within the waste-derived mesoporous powder sorbents (MPS) series. Employing the static adsorption technique, the impact of both adsorption temperature and amine loading on the CO 2 adsorption efficacy was comprehensively investigated. The optimized sample, MPS-TEPA-30, demonstrated a superior CO 2 adsorption capacity, achieving 2.22 mmol g −1 at 323 K and 1 bar, a significant 6.8-fold increase compared to the unmodified MPS material (0.326 mmol g −1 ). Additionally, MPS-TEPA-30 demonstrated notable performance advantages, surpassing SBA15-TEPA-30 and MCM41-TEPA-30 with near 1.49- and 2.12-fold increases in adsorption capacity, respectively. Impressively, MPS-TEPA-30 exhibited remarkable adsorption ability beyond 1.5 mmol g −1 at ultralow pressures (<0.01 bar), suggesting its potential for ambient ultralow-pressure CO 2 capture. Moreover, MPS-TEPA-30 showed exceptional stability over multiple adsorption–desorption cycles, with only a marginal 6 % decrease in CO 2 capture efficiency after the seventh cycle. Thermogravimetric analysis confirmed the robust thermal stability of the amine-functionalized adsorbent (∼473 K), rendering it suitable for high-temperature adsorption–desorption processes. The Ideal Adsorbed Solution Theory (IAST) equation predicted an excellent adsorption selectivity of 1600 for the CO 2 /N 2 (1:1) mixture at 323 K and 10 mbar, underscoring the promising prospects of MPS-TEPA-30 in CO 2 capture and selective separation applications from ambient condition.