Desorption processes: Supercritical fluid regeneration of activated carbon

✍ Scribed by F. Recasens; B. J. McCoy; J. M. Smith

• Publisher: American Institute of Chemical Engineers
• Year: 1989
• Tongue: English
• Weight: 599 KB
• Volume: 35
• Category: Article
• ISSN: 0001-1541
• DOI: 10.1002/aic.690350608

✦ Synopsis

Models are developed for isothermal desorption in a fixed bed of adsorbent particles. While more general models require numerical solution of the governing equations, two practically important cases have analytical solutions: 1) an equilibrium desorption model where the rate of desorption is controlled by external and intraparticle mass transfer; and 2) a kinetic model where external and intraparticle mass transfer and a first-order irreversible desorption step control the overall process.

Recent experimental data (Tan and Liou, 1988) for the desorption of ethyl acetate from activated carbon with supercritical carbon dioxide are found to fit the local-equilibrium model. Data for the effect of temperature on fractions desorbed indicate a reversal of the temperature dependence of the adsorption isotherm as the supercritical pressure is increased. This phenomenon is analogous to the observed cross-over region for the effect of temperature on the solubility of a solid at supercritical conditions.