Adsorption Behaviour of Tween80 on Graphite

Abstract

Techniques including thermogravimetry (TG), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were applied to characterize the adsorption behaviour of Tween80 on graphite. TG is a suitable method for determining the amount of Tween80 adsorbed since it is not restricted by the large amount of solvent adsorbed in this disperse system. The results indicate that TG may provide an alternative method for measuring the amount adsorbed in some disperse systems in which there are significant differences between the thermal behaviours of the adsorbate, adsorbent and solvent. The adsorption isotherms of Tween80 were of the Langmuir type, with the adsorbed amount attaining a maximum value at temperatures between 30°C and 50°C. XPS and FT-IR measurements were used to provide detailed information about the functional group shift. In addition, AFM images indicated that the adsorption of Tween80 has a considerable influence on the topography of graphite, with the adsorbate being adsorbed preferentially on the step defect sites at the edge of the graphite crystal.