A Real Adsorbed Solution Theory model for competitive multicomponent liquid adsorption onto granular activated carbon

Multicomponent adsorption of gas mixtures on diverse solid surfaces is important in many applications. However, there are still many questions on the practical applicability of the available theories, especially for polar systems. In this work, we consider three well-known theories suitable for the prediction of multicomponent adsorption with parameters obtained solely from correlating single gas/solid data. We have tested them over an extensive database with emphasis on polar systems (both gases and solids). The three theories are the multicomponent Langmuir, the ideal adsorbed solution theory (IAST), and the multicomponent potential adsorption theory (MPTA). We have not attempted to improve/modify the methods in any way but have used them in their original form, as the purpose of our work is to illustrate the capabilities and inherent limitations of the models for predicting multicomponent adsorption. We have ensured that the description of single gas/solid systems is as accurate as possible, but beside...

Capabilities and Limitations of Predictive Engineering Theories for Multicomponent Adsorption

Uncertainties in determining microbial biomass C using the chloroform fumigation-extraction method

The role of the porosity and oxygen groups on the adsorption of n-alkanes, benzene, trichloroethylene and 1,2-dichloroethane on active carbons at zero surface coverage

Adsorption of benzene mixtures on silicalite-1 and NaX zeolites

Qualitative and quantitative characterization and prediction of multicomponent adsorption equilibria are essential for design of environmental remediation processes such as soil vapor extraction, bioventing, and thermal desorption. Single component, binary- and ternary-mixture isotherms on silica gel were measured by the frontal analysis chromatography technique. Binary organic mixtures were composed of environmentally relevant VOCs, hexane/benzene (nonpolar/nonpolar), and hexane/trichloroethylene (nonpolar/slightly-polar). Water binaries were water with hexane, benzene, or trichloethylene. Organic mixtures exhibited enhanced adsorption, where the adsorbed amount for each component was increased due to the second component. Water/hexane and water/benzene mixtures showed noncompetitive adsorption, where water adsorbed onto polar sites and n-hexane or benzene adsorbed onto nonpolar sites. Competition for polar adsorption sites was observed for the trichloroethylene adsorption in water. Adsorption data of n-hexane/benzene/water showed that n-hexane and water were independently adsorbing onto different adsorption sites. Furthermore, n-hexane and benzene with water showed the same adsorption behavior as without water. For the mixture of n-hexane/trichloroethylene/water, only the amount of water adsorbed was reduced compared to the pure species adsorption of water. The adsorption equilibria of n-hexane and trichloroethylene were not influenced in comparison to their pure species isotherms. Mixture isotherms were modeled with IAST, MSAM, and RAST. The nonideal adsorbed phase was characterized using activity coefficients.

Thermodynamic modeling of binary and ternary adsorption on silica gel

Qualitative and quantitative characterization and prediction of multicomponent adsorption equilibria are essential for design of remediation processes such as soil vapor extraction, bioventing, and thermal desorption. The effects of physical properties of volatile organic components (VOCs) on adsorption equilibria were investigated by measuring single-component and binary-mixture adsorption isotherms on a polar adsorbent, silica gel, employing the frontal analysis chromatography technique. The binary mixtures were n-hexane/benzene (nonpolar/nonpolar), n-hexane/trichloroethylene (nonpolar/slightly polar), and chloroform/chlorobenzene (polar/polar). The adsorption isotherms for the single components were BET type II isotherms, indicating physical multilayer adsorption. The monolayer uptake increased with the increasing polarity of the components. The adsorption isotherms of the binary mixtures of n-hexane/benzene and n-hexane/trichloroethylene were BET-type II. For the chloroform/chlorobenzene mixt...

Dirk G. Steffan

Papers

Thermodynamic modeling of binary and ternary adsorption on silica gel

Single-Component and Binary-Mixture Adsorption of Volatile Organic Contaminants on Silica Gel