Electro-peroxone regeneration of phenol-saturated activated carbon fiber: The effects of irreversible adsorption and operational parameters

This study investigated the regeneration of phenol-saturated activated carbon fiber (ACF) by an electro-peroxone (E-peroxone) process. Results show that approximately ∼30% of the sorbed phenol was irreversibly adsorbed on ACF, and could not be effectively desorbed by conventional cathodic regeneration. Therefore, the cathodic regeneration restored only about 68% of the adsorption capacity of ACF for phenol reloading. In comparison, by combining the cathodic regeneration with ozonation, the E-peroxone regeneration process could oxidatively convert irreversibly sorbed phenol to more desorbable transformation products, and thus enhanced the regeneration efficiency up to ∼90%. Due to the irreversible adsorption of phenol and oxidation of ACF by oxidants such as O3 and OH, the adsorption capacity of ACF declined during multiple cycles of phenol adsorption and E-peroxone regeneration, especially when high ozone dose was used in the regeneration. By optimizing the ozone dose, the modifications of ACF properties due to O3 and OH oxidation could be minimized. Consequently, after twelve cycles of the E-peroxone regeneration, the ACF retained still ∼72% of the adsorption capacity of the virgin control. These results suggest that the E-peroxone process may provide a more effective alternative to conventional cathodic regeneration for the regeneration of ACs saturated with irreversibly sorbed organics.