Enhanced in situ production of Fenton reagent's by nanobubble aeration and sacrificial iron anodes in the electro-Fenton process

Wastewater treatment is currently focused on the development of simple, safe, cost-effective technologies for the complete destruction of persistent organic pollutants. A novel reagent-free electro-Fenton process by integrated nano-bubble aeration and sacrificial iron anode is proposed, which improves mass transferability of large content dissolved oxygen (10.55mgL-1) in the electrolyte and then quickly transported oxygen to the electrode surface. The synergistic effect of nanobubble aeration and sacrificial iron anodes can product a highly efficient hydrogen peroxide (H2O2) (310 mgL-1) and enhanced electrochemically driven reduction of Fe2+ at pH 3.5 and current density 55 mAcm-2. The degradation of phenol (100 mgL-1) with hydroxyl radicals (⋅OH) generated in situ is described by a pseudo first-order kinetics mode and was fast (0.036 min-1), which obtained a remarkable decolorization of over 58.7% in 60 min. With nanobubble aeration and sacrificial iron anode, the catalytic decomposition of H2O2 to ⋅OH by Fe2+ was more powerful, achieving a cost-effective and green design without reagents.