Evolutionary Characteristics of Sulphate Ions in Condensable Particulate Matter Following Ultra-Low Emissions from Coal-Fired Power Plants During Low Winter Temperatures

Coal-fired power plants exacerbate hazy weather under low winter temperatures, while sulphate ions (SO 4 2− ) in condensable particulate matter (CPM) emitted from ultra-low emission coal-fired power plants accelerate sulphate formation. The transformation of gaseous precursors (SO 2 , NOx, NH 3 ) is the main pathway for sulphate formation by homogeneous or non-homogeneous reactions. For the sustainability of the world, in this paper, the effects of condensation temperature, H 2 O, NO X and NH 3 on the SO 4 2− generation characteristics under low-temperature rapid condensation conditions are investigated. With lower temperatures, especially from 0 °C cooling to −20 °C, the concentration of SO 4 2− was as high as 26.79 mg/m 3 . With a greater proportion of H 2 SO 4 in the aerosol state, and a faster rate of sulphate formation, H 2 O vapour condensation can provide a reaction site for sulphuric acid aerosol generation. SO 4 2− in CPM is mainly derived from the non-homogeneous reaction of SO 2 . SO 3 is an important component of CPM and provides a reaction site for the formation of SO 4 2− . SO 2 and SO 3 , in combination with Stefan flow, jointly play a synergistic role in the generation of SO 4 2− . The content of SO 4 2− was as high as 36.18 mg/m 3 . While NO X sometimes inhibits the formation of SO 4 2− , NH 3 has a key role in the nucleation process of CPM. NH 3 , SO 2 and NO X have been found to rapidly form sulphate with particle sizes up to 5 µm at sub-zero temperatures and promote the formation of sulphuric acid aerosols.