Modeling Analysis of Two Common Organic Pollutants' Adsorption and Desorption from Activated Carbon, C60, and Soil Organic Carbon

As one of the most important elements in the environment, carbon dictates the transport and fate of hydrophobic organic pollutants. Adsorption is the most common mechanism of organic pollutant attachment to carbonaceous materials, a process that can be illustrated by an adsorption isotherm. In this study, a series of adsorption-desorption experiments have been carried out to investigate the desorption hysteresis and modeling fitting of naphthalene and 1,2-dichlorobenzene with three types of carbonaceous materials, including fullerene C-60, activated carbon, and soil organic carbon. Sorption models evaluated include Freundlich, Langmuir, two-compartment dual-equilibrium desorption, and Polanyi-Manes isotherms. Results of model fitting of adsorption-desorption data with each isotherm were compared and discussed. Moreover, the possible mechanism controlling the adsorption process can be deduced according to the Polanyi-Manes model. This is the first report concerning the comparison of model fitting of these four different adsorption isotherms based on experimentally obtained organic pollutant adsorption-desorption data. This reported study can expand our knowledge of sorption and especially desorption characteristics of organic pollutants with different forms of carbonaceous materials.