A Molecular Simulation and Experimental Study of the Effect of Phenolic Hydroxyl on the Adsorption of Dibenzothiophene on Activated Carbon

The interaction between phenolic hydroxyl on activated carbon and dibenzothiophene was investigated by using density function theory and by the absorption experiments.The theory of Atoms in Molecules was used to calculate the theoretical charge density and the Laplacian of the complex adsorption system.The electron distribution of the system was analyzed by performing the natural bond orbital calculations for the monomers and adsorption complex.Based on the theoretical study of the complex adsorption,it was found that there exists hydrogen bonds between the electron systems(C1=C2) of dibenzothiophene and the anti-bond orbital(﹡O33-H34) of the phenolic hydroxyl.When the hydrogen bond is formed,some charge(5.29×10 22 C) is transferred from C1=C2 to ﹡O33-H34 and the interaction energy is 7.97 kJ mol 1.The adsorption amounts of dibenzothiophene on activated carbons with different amounts of phenolic hydroxyl were measured.The results show that the dibenzothiopheneon adsorption amount and the absorptive power of the activated carbon increase with the increase of the amount of phenolic hydroxyl on the activated carbon,which indicates that the increase of phenolic hydroxyl amount on activated carbon offers more adsorption sites for dibenzothiophene adsorption.When the phenolic hydroxyl on the oxidized activated carbon increases from 0.14 to 0.38 mmol g 1AC,its dibenzothiophene adsorption amount increases by 52%(from 9.3 to 14.1 mgS g 1AC),which is in good agreement with the theoretical results.The investigation provides valuable information for developing novel adsorbents for ultra-deep desulfurization of liquid fuels.