Enhanced flow-through electro-Fenton process based on rGO aerogel cathode: Essential role of sodium tetrapolyphosphate

As a promising advanced oxidation process , electro-Fenton (EF) technology could in-situ generate H 2 O 2 through 2e - oxygen reduction reaction (ORR), and then activate H 2 O 2 into reactive oxygen species to degrade the organic pollutants in wastewater. However, its practical application is limited by the sluggish ORR kinetics and acidic condition (pH < 3), which requires external addition of acids, ferrous salts (Fe II ) or even H 2 O 2 . To improve the efficiency of wastewater treatment , targeted development on EF technology based on specific application scenario is also critical. In this contribution, a flow through EF system was developed to remove the antibiotic pollutants in the meat processing wastewater, where the EF process was significantly enhanced by the reduced graphene oxides (rGO) aerogel cathode and the presence of polyphosphates (PPs). The interconnected 3D porous configuration of rGO aerogel with abundant oxygen functional groups greatly facilitated the mass and electron transfer during the flow-through EF process. Meanwhile, the formation of PPs film on the surface of sacrificial iron anode ensured continuous releasing of Fe II under near-neutral condition without rusting, and the generation of Fe II -PPs complexes effectively compensated the production of H 2 O 2 via the pathway of molecular oxygen activation. Moreover, 99.9% of phosphorus can be recycled and reused in the flow-through EF system by coupling the nanofiltration technology, enabling efficient removal of antibiotics and utilization of PPs in the wastewater.