Adsorption on activated carbon: Comparison of molecular simulation with experiment
Activated carbon has a microporous structure that is highly disordered. The shape of these micropores is highly irregular and leads to geometric hetero-geneity. In addition, chemisorbed groups on the edges on the graphite lamellae introduce a chemical heterogeneity that affects the adsorption of polar adsorbates. The objective of this work is to study the effects of both structural and chemical heterogeneity upon adsorption of methane and carbon dioxide. Grand Canonical Monte Carlo simulations are performed to provide a fundamental understanding of the microscopic behavior of adsorption. This method is used to generate adsorption second virial coefficients, isotherms and heats of adsorption. Intermolecular interactions are described by Lennard-Jones potentials. For polar adsorbates, an additional potential to account for polar interactions is included. The structure of activated carbon is modeled by monodisperse slit and polyhedral pores. In addition, a new strip model is presented, which utilizes semi-infinite graphite planes arranged in a configuration matching that of a real activated carbon. The surface area and porosity of the models match those of the real activated carbon. Results of the simulations are compared with experimental volumetric and gravimetric adsorption data in order to determine the viability of model predictions. Heats of adsorption are especially sensitive to the model energetics and are the criteria for judging models.
Stella, Albert, "Adsorption on activated carbon: Comparison of molecular simulation with experiment" (1993). Dissertations available from ProQuest. AAI9413911.