Abstract:

This paper aims to investigate the efects of different metal ions loaded on activated carbon(AC)on the activation energy of phenol desorption.In the investigation,six kinds of metal ions were respectively loaded on the AC surface by means of impregnation.Then,the activation energies of phenol desorption from the six kinds of modified activated carbons were determined using the temperature-programmed desorption(TPD)technique,and the efects of metal-ion loading on the desorption activation energy were an alyzed and discussed with the help of Hard Soft Acid Base(HSAB)principle.The results show that the activation energies of phenol desorption from Al(9I)/AC,Mg (II)/AC,Fe(Ⅲ)/AC and Ca(II)/AC are all larger than those from the original AC,while the activation energies of phenol desorption from Ag(I)/AC and Cu(II)/AC are smaller.According to the HSAB pfin-ciple,phe-nol belongs to hard base,the loadings of hard acid ions AI ,Mg ,Fe an d Ca on AC lead to an increase in the local acid hardness of AC surface,thus improving the adsorption for phenol.However,since Ag an d Cu are respectively soft acid an d borderline acid ions,the loadings of Ag an d Cu on AC result in a decrease in the local acid hardness of AC surface,thereby,the surface adsorption for phenol becomes weak to some extent.

Key words: activated carbon, phenol, metal coating, temperature-programmed desorption, Hard Soft Acid Base principle