Heterogeneous reactions of sulfur dioxide on dust

The source of urban atmospheric particles is broad, and the major source is the building dust from urban construction. Calcium is the tagged element and Portland cement is the major component of building dust. In this study, CaO was regarded as the representative oxide of building dust, and mixtures were synthesized in terms of the major element ingredients of building dust. The heterogeneous uptake of SO2 on CaO, mixtures, Portland cement and building dust samples was investigated. In situ FTIR and X-ray photoelectron spectroscopy (XPS) were used to identify the products of the reactions. In addition, the crystal phases and the surface properties of the samples were characterized by XRD patterns and BET specific surface area. The results show that in the presence of oxygen, sulfur dioxide can be adsorbed to sulfite and further catalytically oxidized to sulfate on the surface of CaO, the mixtures, Portland cement and building dust. The reactivity of SO2 on the surface of dust and oxides is basically a first order. The main ingredient of building dust sample is SiO2, and the one of Portland cement is Ca3SiO5.