Adsorption and thermal desorption behavior of asphalt-like functionalities on silica

The adsorption and thermal desorption behaviours of seven model compounds containing asphalt-like functionalities were studied on silica. Adsorption isotherms of the model compounds were examined at 25°C and analyzed via the Langmuir isotherm. A series of temperature-programmed desorption (TPD) experiments was also conducted on the silica samples, the activation energy for desorption (E_d) being determined by conventional TPD analysis. The adsorption and thermal desorption behaviours were correlated in terms of the activation energy (E_{d tot}) for complete desorption. Dimethyl sulphoxide showed the strongest adsorption and the largest value for E_{d tot}, implying that the high energy consumption necessary to desorb such functionalities plays a key role in the durability of asphalt-aggregate bonding.