Fig. 5. (a) Sorption isotherms of 1,4 dichlorobenzene (DCB) to Pahokee peat (PP) after 14 and 35 d equilibration and Beulah-Zap lignite (BZL) after 21 and 35 d equilibration. Regression lines represent Freundlich fits to the 35 d sorption data. DCB was determined by gas chromatography for the 14- and 21-d isotherms and by scintillation counting for all other experiments. (b) Desorption kinetics of DCB from PP and BZL. The term C* is the hypothetical concentration if all DCB mass was in solution, C_eq is the equilibrium concentration after desorption. Note that the data are plotted over the square root of time. The term C is the solute concentration, and q is the sorbed concentration.