Transport and sorption of organic gases in activated carbon

The relationships among adsorption-desorption kinetics, equilibrium partitioning, and fixed-column breakthrough curves are elucidated for airborne benzene and vinyl chloride on activated carbon grains and fibers. An electrobalance is used to measure adsorption/desorption kinetics and to obtain equilibrium partitioning data; column experiments are conducted to determine additional equilibrium partitioning data and to measure breakthrough curves. A porous sphere/cylinder intragrain diffusion model, coupled with a Freundlich isotherm to describe equilibrium partitioning, conforms closely to the experimental kinetic data for both adsorption and desorption. In addition, it is shown that the adsorption isotherm may be accurately predicted based on the asymmetry between adsorption and desorption rates measured in a single kinetic experiment. The parameters extracted from the kinetic experiment, when combined with the appropriate transport equations, can be used to accurately forecast column breakthrough curves.