Activation Energy for Desorption of Benzene on Modified Activated Carbons

This work mainly involves the study of activation energy of benzen desorption on modified activated carbons.Three kinds of activated carbons such as KH560/activated carbon,1706/activated carbon,and A172/activated carbon were prepared by means of the surface modification of organic silicon alkyl.Temperature-programmed desorption(TPD)experiments were conducted to measure the TPD curves of benzene on the activated carbons and estimate the activation energy for desorption of benzene on the modified activated carbons.The results showed that the activation energy for desorption of benzene on the KH560/activated carbon,1706/activated carbon and A172/activated carbon separately was 25.968,23.134 and 18.076 kJ/mol,which were higher than that on unmodified activated carbon,17.911 kJ/mol.It indicated that the use of organic silicon alkyl to modify the surfaces of activated carbon could improve its adsorption of benzene.The results of inverse gas chromatography(IGC)showed that specific interaction free energy for adsorption of benzene on the activated carbons was negative,which meant that this adsorption was spontaneous,the specific interaction free energy for adsorption of benzene on the modified activated carbons was smaller than that on the unmodified activated carbon,and the smaller the specific interaction free energy,the higher the activation energy required for the desorption of benzene on activated carbon.