Adsorption behavior of phenol in aqueous solution on MCM-41 grafted by different functional groups

Four types of organo-functionalized mesoporous silicas were synthesized by post-grafting method, and characterized by powder X-ray diffraction, nitrogen adsorption/desorption and fourier transform infrared spectroscopy. In addition, adsorption behaviors of the prepared material modified with different functional groups were studied by adsorption of phenol in aqueous solution. When the concentration of phenol was 800 mg/L, the equilibrium adsorption capacity of N-aminoethyl- γ-aminopropyl-MCM-41, aminopropyl-MCM-41, mercaptopropyl-MCM-41 and propyl-MCM-41 was respectively as 2.5 times, 2.2 times, 1.9 times, and 1.7 times as that of MCM-41. It was due to the introduction of organo-functional groups, changing the polarity of the channel surface, and increasing the hydrophobic properties. N-aminoethyl-γ-aminopropyl and aminopropyl groups could generate acid-base interactions with phenol, therefore, their adsorption capacity increased much more. Besides, the pH value of the solution could significantly affect the adsorption amount of phenol on samples. The result showed that with the increase of pH, the adsorption amount of phenol increased at first, and then decreased. The maximum adsorption amount of all the prepared materials occurred at about pH value of 6.