Simultaneous removal of SO, NO and Hg using an enhanced gas phase UV-AOP method.

The core for simultaneous removal of SO, NO and Hg is the oxidation of NO and Hg. Radical induced oxidation of NO and Hg is considered to be the most efficient method. We develop a novel gas phase advanced oxidation process (AOP) of UV-Heat/HO-NaClO to simultaneously remove SO, NO and Hg due to a great synergism between HO and NaClO under thermal and ultraviolet (UV) co-catalysis. The results indicated that the SO removal was always good, while the removal of NO and Hg was affected by NaClO and UV. Higher catalytic temperature and longer flue gas residence time favored the removal of NO and Hg. The presence of SO and NO facilitated Hg removal. Kinetics analyses were conducted to provide the reaction rate of removal of NO and Hg under different conditions. X-ray photoelectron spectroscopy (XPS) revealed the product composition as Cl, Hg, NO and SO. Electron spin resonance (ESR) tests confirmed the generation of HO. Cost analyses demonstrated the better cost performance of the proposed method compared to SCR-ACI combined method. HO and ClO were proved to be the main oxidant. The reaction mechanism for removal of NO and Hg by using UV-Heat/HO-NaClO were proposed finally.