Enhanced CO2 capture via calcium looping with mesoporous ladle furnace stainless steel slag

• Ladle furnace slag (LFS) was investigated for CO 2 sequestration in the calcium looping (CaL) process. • Mesoporous composites were developed from LFS for enhanced CO 2 uptake. • Modified LFS achieved 7.55 g CO 2 /g sorbent, a 47 % increase over bare LFS. • Modified LFS maintained performance over 20 CaL cycles, indicating superior durability. • LFS for CO 2 capture offers a sustainable solution to repurpose industrial waste. CaO-based materials have attracted considerable interest because of their potential roles in thermochemical CO 2 capture via the calcium looping (CaL) process. The steel manufacturing sector inevitably generates substantial amounts of slag as a by-product, posing environmental issues such as soil contamination if left untreated. Despite its abundance and low cost, steel slag, which contains 20–60 % CaO, has not been extensively researched for its potential in the CaL process. This study introduces ladle furnace slag (LFS) as an optimal CaO-rich material for developing mesoporous composites to improve CO 2 sequestration in the CaL process. Using an autoclave reactor/muffle furnace setup, we conducted a parametric investigation on operational variables including reaction time, temperature, pressure, and liquid-solid ratio and determined the kinetics of carbonation/calcination reaction of CaL process. Our findings reveal that the CO 2 capture performance of modified LFS surpassed that of the bare LFS, achieving a CO 2 uptake of 7.55 ± 0.01 g per g of sorbent over 20 cycles. Additionally, the modified LFS exhibited the capability to undergo a minimum of 20 regeneration cycles, reaching steady state after the 15th cycle with minimal variation of 0.01 g per g of sorbent. The enhanced stability was linked mainly due to the presence of ceramics such as Al 2 O 3 and Fe 2 O 3 in ratios of 1:5 and 1:6.5 respectively, with respect to CaO, achieved through acid etching. Such mineralogical transformation of the modified LFS improved its resistance towards sintering while ensuring 100 % recycling of metals in the LFS. Therefore, this study highlights the sustainable utilization of LFS as a valuable and efficient sorbent for CO 2 capture, showcasing its potential for repurposing in environmental applications.