Thermal reactivation of ammonia-tailored granular activated carbon exhausted with perchlorate

Thermal reactivation with CO2 or NH3 at temperatures higher than 700 degrees C effectively restored the perchlorate adsorption capacity of ammonia-tailored carbon. In contrast, steam regeneration restored only a portion of the perchlorate adsorption capacity, and these distinctions were attributed to the change in surface chemistry that was induced by regeneration. After perchlorate loading, regenerating the ammonia-tailored GAC via CO2, or NH3 preserved the nitrogen content and positive surface charge density of the initial ammonia-tailored activated carbon. In contrast, steam regeneration caused a decrease in nitrogen content and positive surface charge. Perchlorate breakthrough was monitored in rapid small-scale column test (RSSCT) operations with either CO2 or NH3 regeneration. 4000-4500 bed volumes of perchlorate adsorption life could be achieved through at least three cycles of RSSCT operation and regeneration. This compared favorably to the 4500 bed volumes that had been achieved when using the initial ammonia-tailored carbon. (C) 2005 Elsevier Ltd. All rights reserved.