Insights into modeling adsorption equilibria of single and multicomponent systems of organic and water vapors

Water vapor is often present in industrial gas streams. This renders modeling of water vapor-based multicomponent adsorption a priority in gas-separation, gas-purification, and air pollution control systems. Over the last five decades, several multicomponent competitive adsorption isotherm models were developed and verified with experimental data, with some being more commonly used (ideal adsorbed solution theory, real adsorbed solution theory, extended Langmuir) than others (virial mixture coefficient, method of Manes, method of Okazaki et al., method of Doong and Yang). Majority of these models are extensions of single-component adsorption isotherms (Langmuir, Freundlich, Toth, Dubinin-Radushkevich, Dubinin-Astakhov, Do and Do, Cooperative Multimolecular Sorption, etc.) or use them as inputs. Therefore, the accuracy of single-component adsorption isotherms is critical to the reliability of the multicomponent isotherms. Understanding the kinetics of an adsorption process is highly crucial, be in a gas-separation/purification system or a regulatory-sensitive air pollution control system. While there are many studies on the kinetics of single-component adsorption, there is less work done on the kinetics of multicomponent competitive adsorption, particularly for systems involving water vapor. This paper presents a review of important single-component and multicomponent adsorption isotherms for organic and water vapors, with the intention of guiding researchers, scientists, and engineers to model comprehensive multicomponent adsorption systems involving both equilibria and kinetics.