Irreversibility effects in liquid desorption of organic solvents from activated carbon

Two methods for the determination of recoveries in the desorption step have been studied: spiking the carbon with subsequent desorption and mixing the sample with the desorbing agent. The former method gave lower recoveries and equilibrium was not reached (irreversible adsorption). Differences between the two methods depended on the sample load and were more pronounced when carbon disulphide was used for desorption than dimethylformamide. These effects seem to be related to the pore size distribution and the chemical nature of the adsorption sites.