Electrothermal swing adsorption of toluene on an activated carbon monolith: Experiments and parametric theoretical study

Abstract

The purpose of the present work is to investigate electrothermal swing adsorption (ESA) process with an activated carbon monolith as adsorbent. Experiments are performed with toluene as VOC. Several parameters are investigated both experimentally and through a mathematical model. It is shown that the monolith, as a carbon material, behaves as a semi-conductor. Its resistivity decreases as temperature and amount adsorbed increase. This leads to different types of evolution of dissipated electrical power during desorption at constant current intensity. The concentration of the desorbed VOC as a function of time has the shape of a peak followed by a tail. This shape is interpreted as a dispersive wave in the sense of the equilibrium theory of adsorption columns. The performance of the process is strongly dependent on the operating conditions. The maximal (that is initial) concentration increases almost linearly with current intensity and purge gas flow rate, and increases also with preheating duration. The purge gas flow rate has mainly an effect of dilution. The efficiency of desorption (% VOC desorbed) is almost constant in average with different preheating times. It increases with current intensity and gas purge flow rate.