Simultaneous absorption of NO and SO2 by combined urea and FeIIEDTA reaction systems

Abstract

SO₂ and NO emitted from coal-fired power plants have caused serious air pollution in China. In this work, a novel mixed absorbent, Fe^IIEDTA/urea, was employed for simultaneous removal of SO₂ and NO in a packed tower, with a corresponding optimal ratio of 0.014 mol L⁻¹ : 5%. The effects of various factors, such as mixed absorbent constitutions, reaction temperature, pH, O₂ concentration, as well as concentrations of SO₂ and NO, on simultaneous removal were investigated. The desulfurization efficiency was 95–99% in all tests, whereas denitrification was affected significantly by various conditions. NO removal efficiency decreased increasing oxygen concentration as well as increasing NO concentration. With an increase in temperature, pH, or SO₂ concentration, NO removal efficiency increased first and then decreased. Under optimal conditions, SO₂ removal efficiency was 100% and NO removal efficiency could exceed 91% within 80 min. The reaction mechanism was speculated according to relevant literature.