Improved phenol adsorption on carbons after mild temperature steam reactivation.

The purpose of this work is to explore steam reactivation at moderate temperatures of activated carbon exhausted with phenol, a highly toxic compound frequently present in industrial wastewater. The spent carbon was treated with steam at various temperatures (450, 600 and 850 degrees C) and times (from 5 to 60 min). Promising results were obtained by applying moderate temperatures and times. Whereas at low temperatures the complete regeneration of the carbon is not accomplished, an almost quantitative desorption of the pollutant was achieved at 600 degrees C after exposure times below 30 min, with minimal damages in the porous network of the carbon. Further reutilization of the regenerated carbon resulted in a superior performance towards phenol uptake. The regeneration efficiency at 850 degrees C strongly depends on the time of reactivation, with an enhanced phenol uptake when short treatment times are applied. Prolonged duration of the regeneration treatment reduced phenol adsorption capacities, due to overreactivation of the carbon in the steam atmosphere, and to the blockage of the porous carbon network.