The Effects of Hydration Process Variables on Surface Properties of MgO/Blast Furnace Ironmaking Slag for CO2 Uptake

Abstract

Abstract This research aims to explore a novel preparation and characterization of modified BFIS slag, with magnesium oxide, ammonium chloride as a hydrating agent, and the MgO/BFIS sorbent, all of which were synthesized utilizing an atmospheric hydration procedure. The sorbents were made by altering the hydration conditions, which included the MgO/BFIS slag weight ratio (1:1 to 1:4), hydration temperature (40–90 °C), ammonium chloride (1–4 g), and hydration length (4–12 h). The carbonation process was carried out using thermogravimetric analysis (TGA) at 800 °C. At all preparation conditions, the specific surface area of MgO/BFIS composite ranged between (50.2–53.6 m 2 /g) and was more than that of MgO (5.34 m 2 /g). The produced MgO/BFIS sorbent had a more porous structure than virgin MgO or BFIS slag, according to SEM micrographs. X-Ray Diffraction (XRD) and Fourier-Transform Infrared spectroscopy (FTIR) analysis revealed the existence of complex compounds comprising magnesium silicate hydrate in the produced sorbents. This helped to explain the large BET-specific surface area. The Brunauer–Emmett–Teller (BET) specific surface area decreased as the amount of BFIS slag increased and increased with the hydration temperature, time, and amount of hydrating agent increased. The shrinking core model was used to fit the kinetics of the carbonation reaction, and the results show that diffusion over the product layer was the rate-limiting step. Graphical Abstract