When computer simulations were performed in the grand canonical ensemble, adsorption
isotherms for benzene, toluene, and p-xylene in Heulandite zeolite were constructed. Nitrogen
adsorption was simulated to test a feasible computational strategy. Simulations were performed
at three temperatures (200, 298, and 473 K), at pressures ranging from 0 to 200 kPa, and at
water contents ranging from 0% to 4%. It was found that the adsorption of the organic species
was not significantly affected by increasing the pressure over 10 kPa. Also, increasing the water
content of the zeolite reduced the adsorption of these aromatics significantly. On the other hand,
as the temperature was increased the amount of adsorbed material was only slightly affected.
To access adsorption selectivity information, various mixtures of the aromatics were studied.
Results from the simulations show that adsorption of benzene was higher than that of toluene,
and toluene adsorption was higher than that of p-xylene. A relation between the electronic
environment of the molecular species and the amount of adsorbed material was established.
The results obtained are compared with experimental data available on other synthetic and
natural zeolites.
Detection of Explosive Related Chemicals (ERCs) emanating from landmines is strongly influenced by fate and transport processes in variably saturated soils, which are affected by many environmental factors. To study the fate and transport behavior of ERCs in soils, it is necessary to conduct experiments is physical models designed for this purpose. Sampling and analysis of the chemicals in soil water and air is one of the most important components of this design.In this project, air and water sampling devices and methods for sampling TNT and DNT in a tropical sandy soil were studied. Different stainless steel porous samplers were evaluated to determine sampling volumes and efficiencies. Results show that they can be used with proper extraction vacuum and pore size depending on soil water content. The stainless steel porous samplers show no or little effect of the sampling efficiencies of TNT and DNT.
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