FeOCl-confined activated carbon for improving intraparticle Fenton-like oxidation regeneration

Highly efficient oxidation, as non-thermal regeneration technology, is a promising method to solve the regen-eration problem of spent activated carbon (AC) in wastewater treatment. In this study, FeOCl was confined into activated carbon (FeOCl/AC) for catalytic oxidation of contaminants on AC during the regeneration process. The characterization results of FeOCl/AC showed that amorphous FeOCl was distributed in micropores, mesopores and macropores of AC. The methylene blue (MB)-adsorbed FeOCl/AC had a regeneration efficiency of 93.7 % at neutral pH in the presence of H2O2, much higher than 46.9 % by Fenton oxidation and 33.7 % by H2O2 oxidation. Meanwhile, the spent FeOCl/AC after the adsorption of atrazine, 2,4-dichlorophenol, and ofloxacin had the regeneration efficiencies of 71.5 %, 86.4 %, and 100 %, respectively. Moreover, the regeneration efficiency still reached 87 % in the fifth adsorption-regeneration cycle, and was linearly decreased with the increase of adsorbed amounts of MB. During 6 h regeneration of spent FeOCl/AC, 97 % of adsorbed MB was degraded. Electron paramagnetic resonance and radical trapping experiments indicated that both superoxide and hydroxyl radicals were involved in MB oxidation during the regeneration process.

Automated summary

In this study, FeOCl confined into activated carbon (FeOCl/AC) was used for catalytic oxidation of contaminants on spent activated carbon. The results showed that FeOCl/AC had high regeneration efficiency and remained stable even after multiple cycles of adsorption and regeneration.