Abstract: Aiming at the problems of the solid-liquid separation difficulties and the poor adsorption performance when the Al₂O₃ and expanded graphite (EG) were used separately as adsorbants, the nano Al₂O₃/EG was prepared with EG as aggregate,   Al(NO₃)₃9H₂O as aluminum source,  NH₃H₂O as precipitant and anhydrous ethanol as dispersant.  The adsorbents were characterized by Fourier transform infrared   (FT-IR) spectrosopy,   X-ray diffraction  (XRD) and  scanning electron microscopy (SEM). The effects of ammonia water addition,  activation temperature,  activation time,  the mass ratio of Al₂O₃ to EG and impregnation time on the adsorption properties of Al₂O₃/EG  on Congo red were investigated. The results show that nano Al₂O₃ is successfully loaded on the EG,  and when ammonia water is added drop by drop,  the activation temperature is 170 ℃,  the activation time is 3 h,  the mass ratio of Al₂O₃ to EG is 0.06∶1,  the impregnation time is 20 min,  the adsorption effect is best,  and the decolorization rate is about 86%. Compared with EG and Al₂O₃,  respectively,  the decolorization rate of Al₂O₃/EG is obviously increased,  which is more than 2 times that of EG, and Al₂O₃/EG is easier to separate than Al₂O₃ in separation operation after adsorption.

Key words:  , expanded graphite,  , aluminium oxide, Congo red,  , decolorization rate,  , characterization