Simultaneous removal of multi-pollutants from flue gas by a vaporized composite absorbent

An economical process that was used to remove SO₂, NO and Hg⁰ simultaneously was developed, based on the pre-oxidations of Hg⁰ and NO by a vaporized Fenton-based complex oxidant (FO) consisted of Fenton and NaClO. The effects of concentrations of FeSO₄ and NaClO in the oxidant, the molar ratio of vaporized oxidant to multi-pollutant, the oxidant solution pH, the reaction temperature, the gas flow ratio of vaporized FO to multi-pollutants, the flue gas flow and the concentrations of coexistence gases in flue gas on the simultaneous removals were investigated experimentally. The results showed that the removals of NO and Hg⁰ were significantly depended on FeSO₄ and NaClO concentrations, the molar ratio of vaporized oxidant to multi-pollutants, the FO solution pH, the reaction temperature, the gas flow ratio of vaporized FO to multi-pollutants and flue gas flow. And higher concentration of SO₂ and an appropriate concentration of NO had the promotion for Hg⁰ removal. The average simultaneous removal efficiencies of 100% for SO₂, 81% for NO and 91% for Hg⁰ were obtained under the optimal reaction conditions. According to the characterization of the reaction removal products by SEM, EDS, XRD and AFS, the reaction mechanism was speculated.