Influence of pore structure and pretreatments of activated carbons and water effects on breakthrough dynamics of tert-butylbenzene

Several activated carbons differently pretreated (de-ashed, oxidized, reduced, wetted, frozen, and dried) were investigated using static (equilibrium adsorption of nitrogen and benzene) and dynamic (tert-butylbenzene (TBB)) adsorption methods. Treatments of carbons at relatively mild conditions leading to not great changes in their textural characteristics affect the TBB breakthrough concentration because of changes in the chemistry of the surfaces (oxidized or reduced) and the presence of water in airstream or pre-adsorbed on carbon beds. Oxygen-containing functionalities at a carbon surface change condition of competitive adsorption of nonpolar TBB and polar water molecules. Calculations of distribution functions of adsorption potential (A), energy (E), Gibbs free energy (ΔG  ) of adsorption of benzene and TBB and effective adsorption (first-order) rate pseudoconstant βeβe over different ranges of relative exit TBB concentration c(t)/c0c(t)/c0 (from ≈10−5≈10−5 to 0.01–0.4) reveal nonlinear effects caused by the size of carbon granules, the pore size distributions, the presence of water, oxidation or reduction of the surfaces and other treatments resulting in distribution functions f(y)f(y) with nonzero intensity in relatively broad ranges of the A, E, ΔG  , and βeβe values. There are many factors affecting the breakthrough parameters; therefore, simple linear relationships between these parameters and the structural characteristics (SBETSBET, SDSSDS, VpVp, and VDSVDS) are not observed.

Several activated carbons differently pretreated were investigated using static and dynamic adsorption methods.Figure optionsDownload as PowerPoint slide