(746g) Two-Step Process on Persistent Organic Pollutants Removal – Insight into the Adsorption Loss during the Electro-Fenton Regeneration Process

Electro Fenton (EF) processes are proven effective for the mineralization of organic pollutants yet suffering from the practical challenge in applications. In this study, a cyclic process combining adsorption and electro Fenton process was developed to improve the practicality of the decontamination of organic pollutants. During the adsorption-electrochemical regeneration cycles, a sharp adsorption loss at the beginning of the cycles was observed, and the adsorption capacity further yielded to a plateau (52.4% of the initial capacity of ACF) without continuous loss. The analysis via Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and point of zero charge (pH_PZC) confirmed the stability of the ACF in the process. The further pore structure analysis showed a complete recovery of the pores with sizes above 12 Å, with poor recovery (only 31.52%) of pores with a diameter below 12 Å. We deduced from the results that the loss in adsorption is due to the formation of iron complexes ferrioxalate, which makes micropores inaccessible for the ferric catalyst. Furthermore, the release of organic substances from the spent ACF electrodes during the alkaline elution confirmed the incomplete removal of degradation intermediates accumulation. Overall, our study demonstrated the high feasibility of the cyclic process towards organic pollutants removal and provided a comprehensive image of the EF-based activated carbon regeneration process.