Simultaneous removal of SO₂, NO_x and Hg⁰ by O₃ oxidation integrated with bio-charcoal adsorption

Simultaneous removal of SO₂, NO_x and Hg⁰ by using O₃ and corn bio-charcoal/coconut shell activated carbon was compared in a fixed bed. The effects of temperature, adsorption time and ratio of O₃/NO on the removal efficiency of NO, Hg⁰ and SO₂ by corn/coconut shell charcoal were studied, and the corn/coconut shell charcoal was characterized and analyzed. The results indicated that the oxidation rate of NO and Hg⁰ increases with the increase of O₃/NO ratio, while the oxidation rate of SO₂ first increases and then decreases slightly. The increase of temperature inhibits the oxidation of NO but promotes the oxidation of Hg⁰ and SO₂. At 140 ℃ and O₃/NO ratio of 1.4, the oxidation rate of NO, Hg⁰ and SO₂ is 99%, 78.6% and 3.5%, respectively. As O₃/NO ratio increases from 0.4 to 1.4, the removal efficiency of corn charcoal for NO_x increases from 4.6% to 93%, and coconut shell charcoal increases from 4.5% to 79%. Corn/coconut shell charcoal can reduce part of NO₂ and increase NO concentration at the outlet. NO_x adsorption performance on corn charcoal is relatively better, while those of Hg⁰ and SO₂ on coconut charcoal are relatively stronger. Coconut shell charcoal has stronger physical adsorption capacity than corn charcoal. The relative content of oxygen-containing functional groups C-O and C=O on the surface of corn charcoal is higher than that of coconut shell charcoal, while its relative content of COOH and O=C-O is lower.