Abstract:In this study, three types of aluminum silicate (AS), Fe3+/AS, Cu2+/AS, and Ag+/AS, were prepared using the immersion method to measure the adsorption of menthol by modified AS using a static adsorption method. Temperature programmed desorption (TPD) experiments were conducted to measure the desorption activation energy, Ed, of menthol by modified AS. The variation in menthol Ed was analyzed and discussed using hard and soft acid and base (HSAB) theory. The results indicated that the surface area of the modified AS was significantly increased compared with that of the original AS. The differences were 105.83%, 44.41%, and 32.69% for Fe3+/AS, Cu2+/AS, and Ag+/AS, respectively. The modified materials also had increased menthol adsorption, which followed the order: Fe3+/AS > Cu2+/AS > Ag+/AS > AS. In addition, these modifications changed the binding force between menthol and the AS surface. The Ed of menthol by modified AS was as follows: Ag+/AS > Cu2+/AS > Fe3+/AS. Compared to the original AS, the loading of Ag+ and Cu2+ enhanced the binding force between menthol and AS, whereas the loading of Fe3+ weakened it, which were consistent with the results predicted by HSAB.
