Regeneration of activated carbons contaminated by phenol using supercritical water

The purpose of this study was to efficiently regenerate activated carbons (ACs) saturated with phenol using supercritical water at 260 bar and 400-500 degrees C. Regeneration temperature and time were the variables that most affected the process. Times close to 10 min provided efficiencies of 100%, such that the procedure can be considered to be very fast and efficient. A study of temperature-programmed desorption using liquid and supercritical water as the carrier fluid indicated that a fraction of the phenol retained on the ACs was physisorbed while another fraction was chemisorbed. ACs subjected to successive cycles of adsorption-regeneration were not completely regenerated when the regeneration times were short (3 min). The study also addressed the regeneration of ACs saturated with phenol aged over long periods of time (0.5-60 days). The difficulty in regenerating the ACs increased with the saturation of phenol and the ageing time. (C) 2012 Elsevier B.V. All rights reserved.