Deterioration of activated carbon by oxidants, contaminants and carbon regeneration

Activated carbon (AC) is widely used for removing organic contaminants; however, its finite adsorption capacity may limit the long-term use. Oxidation regeneration of saturated AC is one of the effective measures to recover the adsorptive capacity of AC, even though the deterioration of AC during the regeneration is common. In this study, advanced oxidation process (Fenton combined persulfate system, Fe2+/H2O2/S2I82-) was used to regenerate the saturated AC, the mechanisms of AC deterioration were evaluated, and the interactions of oxidants, contaminants, and AC during the adsorption/regeneration processes were investigated. The results indicate that the oxidants mainly functions on the AC surface, resulting in the deterioration of AC along with the destruction of the sorbed contaminant (e.g., trichloroethylene in this study). Deterioration of AC exposed fresh carbon to the surface, however, such emergence of the fresh carbon to the AC surface does not seem to increase the AC adsorption capacity. Iron precipitation on the surface of AC was also observed during the adsorption/regeneration process, however, it can be partially removed from the surface of AC along with the carbon deterioration.