A preliminary study on sorption, diffusion and degradation of mustard (HD) in cement.

A preliminary study has been done to examine the sorption, diffusion and degradation of mustard (HD) in cement. The sample of dried cement paste is a meso-porous adsorbant with a BET surface area around 40.8 m2/g, which is able to adsorb vapor of HD at room temperature and to result in a multiple-layer isotherm of II type. The molecule of HD seemed to chemically adsorb onto cement surface. Droplet of HD contaminating cement was able to be degraded into less toxic products, but in a very low rate of k = 4.8 x 10(-5) min(-1) and t(1/2) = 16 x 10(4) min at room temperature. Droplet of HD is able to penetrate through the layer of cement, but a cement plate of 8mm can protect against HD droplets over 48 h. A decrease of thickness for cement layer or addition of sand in cement would lead to lower the protection time against HD droplets. The diffusion coefficient of HD molecule in cement was determined, about 1.3 x 10(-4) cm2/min and of a typical diffusion in solid.