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

The thermal desorption in water of phenol, 2-dichlorophenol, 2,6-dichl orophenol, 4-nitrophenol and 2,6-dichloro-4-nitrophenol adsorbed onto an activated carbon is studied by temperature-programmed desorption (T PD) in liquid phase and by temperature-programmed adsorption-desorptio n (TPAD). The TPAD thermograms indicate that the desorption in water o f the five compounds is complete before a temperature of 300 degrees C is reached. The five phenolic compounds are stable below 260 degrees C. Application of the interruption test shows that diffusion controls the desorption of these compounds in water. High-temperature adsorptio n isotherms and TPAD thermograms indicate that readsorption occurs dur ing thermal desorption. Study of TPAD permits the calculation of the a ctivation energies of adsorption and desorption. The values of these e nergies afford values for the adsorption bonding energy that lie withi n the range of the hydrogen bond. Copyright (C) 1996 Elsevier Science Ltd