Simultaneous purifying of Hg 0 , SO 2 , and NO x from flue gas by Fe 3+ /H 2 O 2 : the performance and purifying mechanism

Abstract

Hg⁰, SO₂, and NOx result in heavily global environmental pollution and serious health hazards. Up to now, how to efficiently remove mercury with SO₂ and NOx from flue gas is still a tough task. In this study, series of high oxidizing Fenton systems were employed to purify the pollutants. The experimental results showed that Fe³⁺/H₂O₂ was more suitable to purify Hg⁰ than Fe²⁺/H₂O₂ and Cu²⁺/H₂O_2. The optimal condition includes Fe³⁺ concentration of 0.008 mol/L, Hg⁰ inlet concentration of 40 μg/m³, solution temperature of 50 °C, pH of 3, H₂O₂ concentration of 0.7 mol/L, and O₂ percentage of 6%. When SO₂ and NOx were taken into account under the optimal condition, Hg⁰ removal efficiency could be enhanced to 91.11% while the removal efficiency of both NOx and SO₂ was slightly declined, which was consistent to the analysis of purifying mechanism. The removal efficiency of Hg⁰ was stimulated by accelerating the conversion of Fe²⁺ to Fe³⁺, which resulted from the existence of SO₂ and NOx. The results of this study suggested that simultaneously purifying Hg⁰, SO₂, and NOx from flue gas is feasible.