Study on the initial evaporation rates of distilled sulphur mustard (HD) in concrete using wind tunnel and TD-GC/MSD: effect of drop size and temperature

In this paper, we demonstrate a robust, analytical method for the study of the initial evaporation rates of distilled sulphur mustard (HD) in concrete at various drop sizes and temperatures. We used a 5-cm wind tunnel and thermal desorption (TD) in connection with gas chromatograph and mass spectrometry detection (GC/MSD). Drops of neat HD, ranging in sizes of 1, 3, 6 and 9 µL, were applied to small concrete coupons. The temperatures were either 18°C, 25°C, 35°C or 50°C. The drop of HD rapidly spread in concrete upon its release. The initial evaporation rates of the drop of HD were analysed by TD in conjunction with GC/MSD. The results showed that the initial evaporation rates increased while HD spread over the surface of concrete, then decreased as the contamination was over. We also found that the initial evaporation rates of the drop of HD in concrete are linearly proportional to drop size and temperature. In particular, drop size or spreading factor has a more pronounced effect on the initial evaporation rates of the drop of HD in concrete than temperature.