STUDY OF THE DESORPTION OF PHENOL AND PHENOLIC COMPOUNDS FROM ACTIVATED CARBON BY LIQUID-PHASE TEMPERATURE-PROGRAMMED DESORPTION

摘要

The thermal desorption in water of phenol, 2-dichlorophenol, 2, 6-dichlorophenol, 4-nitrophenol and 2, 6-dichloro-4-nitrophenol adsorbed onto an activated carbon is studied by temperature-programmed desorption (TPD) in liquid phase and by temperature-programmed adsorption-desorption (TPAD). The TPAD thermograms indicate that the desorption in water of the five compounds is complete before a temperature of 300℃ is reached. The five phenolic compounds are stable below 260℃. Application of the interruption test shows that diffusion controls the desorption of these compounds in water. High-temperature adsorption isotherms and TPAD thermograms indicate that readsorption occurs during thermal desorption. Study of TPAD permits the calculation of the activation energies of adsorption and desorption. The values of these energies afford values for the adsorption bonding energy that lie within the range of the hydrogen bond.