Abstract: A series of mesoporous SiO₂/expanded graphite (EG) composites were directly synthesized via a facile one-step hydrothermal method in aqueous solutions that contain templates,aluminum salts,expanded graphite and siliceous source.The weak acid environment of reaction solutions were self-generated by the aluminum salts.The effects of the added amount of aluminum salt in the reaction system on the structures and properties of the obtained composites were carefully investigated.The structures and morphologies of the composites were characterized by XRD,N₂ physisorption and SEM techniques.Methylene blue (MB) was used as a probe pollutant molecule to systematically evaluate the adsorption properties of the composites.The results show that all mesoporous SiO₂/expanded graphite composites have large surface areas and high pore volumes,and they can be prepared by using aluminum salts in a wide range of r_Al/Si=0.25-2.0(pH=3.1-2.3).It is further observed that multi-layered mesoporous SiO₂ membranes are grown onto the carbon flakes of expanded graphite in SiO₂/EG composites.Those SiO₂/EG composites synthesized with r_Al/Si of 0.25,0.5 and 1.0 have well-ordered mesoporous while those synthesized with r_Al/Si of 1.5 and 2.0 have less-ordered mesoporous.Mesoporous SiO₂/EG composite adsorption capacity in 52-55 mg·g^-1,and the adsorption behavior is mainly in accordance with the Langmuir equation and pseudo-second-order kinetic model.