A new kind of composite material(P-silica gel) was prepared by modifying porous silica gel with pectin extracted from the waste pomelo peel,and its adsorption properties to methylene blue(MB) in water sample were investigated by UV spectrophotometry.The composite material was characterized by Fourier transform infrared(FT-IR) spectroscopy.Effects of some factors such as silica gel before and after modification,amount of P-silica gel,pH value,adsorption time, temperature and actual water sample on adsorption of MB were investigated.The adsorption of porous silica gel to MB improved significantly after modified by pectin,and its adsorption capacity increased from 31.6 mg?g-1 to 41.7 mg?g-1.The adsorption capacity of P-silica gel increased with the increase of pH value and temperature,and it was conducive to adsorb MB with P-silica gel in alkaline condition.The maximum adsorption capacity of MB on P-silica gel was 59.2 mg?g-1 when using 5 mg P-silica gel at pH 7.0 and temperature of 50 ℃.Kinetic studies showed that the P-silica gel could adsorb MB rapidly and reached the equilibrium in 120 min.Furthermore,the adsorption behavior of MB on P-silica gel could be described by the pseudo second order kinetic model,which indicated that the process of P-silica gel adsorbing MB was mainly assigned to chemical adsorption.The adsorption isotherms data indicated that the Langmuir model was better than the Freundlich model.The removal rate of MB by P-silica gel could reach above 90% in the environmental water sample.