Estimation of Thermal Desorption Curve and Desorption Efficiency of Organic Solvent from Activated Carbon

Abstract

A simple analytical method is proposed for thermal desorption curves and desorption efficiencies of organic solvent from activated carbon. Basic equations are obtained from mass balance in desorption column, mass transfer of organic solvent vapor from the inside of particles to gas stream, and adsorption isotherm. Two assumptions are made in order to solve these equations analytically.i.e., concentration of solvent vapor is uniform both in the gas and solid phases, and adsorption isotherm is linear. When adsorption isotherm is curved, it is approximated by several straight lines. Comparison of the analytical, process showed that the mass transfer rates of solvent vapors were so rapid, and the shapes of desorption curves were affected mainly by the adsorption isotherm. The estimated desorption curves and desorption efficiencies agreed well with the experimental values for ethyl acetate especially in the case of a large diameter of column. However, the estimated desorption efficiency of toluene was a little lower than the experimental one.