Fig. 2. Measured adsorption-desorption isotherms on either a short-term (closed symbols, 48-h adsorption and 48-h desorption step) or a longer-term (open symbols, 504-h adsorption and 48-h desorption step) basis. Best-fit Freundlich isotherms (Eq. [6]) for adsorption-desorption isotherms are shown as solid lines. data from present study, data from Gamst et al. (2001) measured under similar conditions and time scales.