Knudsen cell and smog chamber study of the heterogeneous uptake of sulfur dioxide on Chinese mineral dust

The heterogeneous uptake processes of sulfur dioxide on two types of Chinese mineral dust (Inner Mongolia desert dust and Xinjiang sierozem) were investigated using both Knudsen cell and smog chamber system. The temperature dependence of the uptake coefficients was studied over a range from 253 to 313 K using the Knudsen cell reactor, the initial uptake coefficients decreased with the increasing of temperature for these two mineral dust samples, whereas the steady state uptake coefficients of the Xinjiang sierozem increased with the temperature increasing, and these temperature dependence functions were obtained for the first time. In the smog chamber experiments at room temperature, the steady state uptake coefficients of SO₂ decreased evidently with the increasing of sulfur dioxide initial concentration from 1.72 × 1012 to 6.15 × 1012 mol/cm³. Humid air had effect on the steady state uptake coefficients of SO₂ onto Inner Mongolia desert dust. Consequences about the understanding of the uptake processes onto mineral dust samples and the environmental implication were also discussed.