Vapor phase adsorption of trichloroethane using organically modified montmorillonite

The vapor of 1,1,1-trichloroethane (TCA) was adsorbed to organically modified montmorillonite (organoclay). Hexadecyltrimethylammonium (HDTMA) was used to modify the surface of the clay and three types of organoclays with different HDTMA loadings were prepared. In adsorption experiments, the three types of organoclays, along with the non-modified (washed) clay were used. TCA was adsorbed from gaseous phase (nitrogen) by using a fixed adsorption bed. The adsorption breakthrough curves and the adsorption isotherms were determined at three different temperatures (24, 34, and 44 °C). The adsorption data were modeled with the Langmuir and BET isotherm equations. It was found that the isotherms of non-modified clay exhibited a favorable Type I behavior, which implies that the adsorption capacity is strongly dependent on vapor concentration at low concentration ranges. In regards to the organoclays, isotherms showed a marginally favorable Type II behavior with a reduced adsorption capacity at low concentrations, and exhibited a linear increase at elevated vapor concentrations. The temperature effect on the adsorption capacities of non-modified clay and organoclays exhibited different patterns. Desorption of TCA from clays was also performed by using pure nitrogen. The desorption rate constant k was in the order of 10−4 min−1 for all types of clay.