Simultaneous removal of sulfur dioxide and nitrogen oxide from flue gas by phosphorus sludge: The performance and absorption mechanism

• Phosphorus sludge, an industrial waste, achieves >95% simultaneous removal of SO2 and NOx at low temperature (55°C), offering a cost-effective solution for small and medium-sized coal-fired boilers. • The absorption mechanism involves Fe3+ and Mn2+ catalyzing SO2 oxidation to sulfate, while yellow phosphorus induces NO oxidation to water-soluble high-valent nitrogen oxides, which are then absorbed as nitrate. • The spent absorption slurry contains valuable acids (H2SO4, HNO3, H3PO4) and can be reused in wet process phosphoric acid production, promoting circular economy. • This green technology addresses the limitations of conventional desulfurization and denitrification methods, such as high costs and secondary pollution, and has broad application prospects.