Experimental investigation of the aerosol-catalyzed oxidation of SO 2 under atmospheric conditions

Abstract

One of the most important processes affecting the chemical and physical form of atmospheric sulfur dioxide is the interaction of gaseous SO 2 with solid or liquid aerosol particles. The investigation of the catalytic activity of some synthetic aerosols and dust particles of different industrial origin under real atmospheric conditions (i.e. a wide range of relative humidity and temperature) have been investigated in the course of an experimental research program at Karlsruhe Nuclear Research Center, Germany. The experiments were carried out in a 4.5 m 3 climate-controlled reaction chamber especially designed for SO 2-experiments in the ppm-concentration range. Starting with SO 2- concentrations of 3–5 mgm −3 the removal of SO 2 from gas phase in the presence of moist aerosol-free air and moist aerosol-polluted air was investigated as was the change of chemical composition of aerosols due to SO 2-adsorption and catalytic oxidation. The results of these experiments with synthetic MnSO 4 aerosols and fly-ash particles of a hard coal fired power plant are presented. They indicate a strong dependence of the catalytic oxidation rate on the relative humidity but no disappearance of the catalytic activity at low relative humidities.