Adsorption of halocarbons to micro-, meso- and non-porous particulate materials

It is important to understand the transport of environmental contaminants in natural environments. Chemical questions concerning the use of tracers for probing surbsurface transport phenomena were studied, focusing on the use of CCl₄, CCl₃F, and CCl₂F₂. Different types of soil constituents in terms of their efficiency for binding and possibly degrading halocarbons at the liquid-solid or gas-solid interface were evaluated. The halocarbons were examined using GC with liquid, headspace, and solid-phase microextraction injection techniques combined with flame ionization and electron capture detection. Adsorption on model soil materials and on specific sandy soil samples was described. This work included microporous aluminosilicate materials such as MFI and faujasite zeolites, mesoporous materials such as silica gels and nonporous particulate matter including SiO₂, Al₂O₃, Fe₂O₃, and humic acids. Even in aqueous solutions, MFI and faujasite zeolites readily adsorbed all CFC-11, CCl₄, and CFC-113 up to their saturation limits in water. Halocarbons in groundwater could be taken up by the surrounding soil and must be considered when modeling halocarbons in tracer experiments.