Microwave-Enhanced Simultaneous SO2 and NO Removal: Performance and Mechanism of Highly Efficient Adsorbents Fabricated from Ti-Bearing Blast Furnace Slag.

The simultaneous removal of SO2 and NO using solid waste-derived materials represents a promising but challenging strategy for complex flue gas purification. Herein, a highly efficient KOH-modified Ti-bearing blast furnace slag (KOH-TS) adsorbent was successfully synthesized via thermal activation at a calcination temperature of 800 °C for 2 h with the addition of 10 wt% KOH. When evaluated at a microwave-assisted adsorption temperature of 200 °C, the KOH-TS adsorbent exhibited exceptional simultaneous desulfurization and denitrification capabilities. Specifically, the T80% and T50% values for desulfurization efficiency were 17.85 min and 63.67 min, respectively, and the T95% and T90% values for denitrification efficiency were 30.63 min and 68.67 min, respectively. The characterization results reveal that this superior performance stems from dual-pathway structural reconstruction during preparation. Macroscopically, thermochemical etching by KOH results in the formation of a hierarchical porous skeleton, whereas microscopically, the isomorphic substitution of potassium ions (K+) into the primary CaTiO3 perovskite lattice induces abundant oxygen vacancies. Consequently, a robust multifunctional adsorbent integrating catalytic oxidation, chemical fixation, and physical confinement was constructed. Mechanistically, the K-doped defective perovskite acts as a catalytic engine to activate oxygen species, synergistically accelerating the continuous oxidation of SO2 and NO. The resulting oxidized intermediates are subsequently neutralized by surface basic sites and securely accommodated as stable sulfates and nitrates within the developed mesopores. This work provides a sustainable and highly efficient "waste-to-wealth" paradigm for multipollutant emission control.