Treatment of gas containing hydrophobic VOCs by adsorption process on raw and intercalated clays

The adsorption of volatile organic compound VOC (o-xylene, m-xylene, p-xylene, benzene, and toluene) as a single solute or as a hydrocarbons mixture was studied by a static headspace coupled to gas chromatography in raw and intercalated clay. Vapor-solid adsorption isotherms of VOC were measured at 20, 30, and 40 A degrees C. Clay was modified with hexadecyltrimethylammonium bromide (HDTMABr). The values of the amounts of VOC adsorbed in HDTMA clay were about 18 times higher than raw clay. It was observed that adsorption capacities of VOCs were strongly dependent on their properties including molecular weight, boiling point, and polarizability. Furthermore, clay materials have higher adsorption affinity for the xylene than for other VOC, which could be attributed to the interaction of its two adjacent methyl groups with clay surface. The adsorption isotherms were fitted with Langmuir, Freundlich, Langmuir-Freundlich, and Toth models. Langmuir-Freundlich model is the best. The evaluation of thermodynamic parameters presents an exothermic and spontaneous adsorption process. Thermal regeneration of raw and HDTMA clays was also investigated to evaluate its efficiency. Therefore, clay materials could be attractive candidate adsorbents for VOC removal.