Coupling electrode aeration and hydroxylamine for the enhanced Electro-Fenton degradation of organic contaminant: Improving H2O2 generation, Fe3+/Fe2+ cycle and N2 selectivity.

• Coupling EA and HA showed a synergy for the Electro-Fenton property at pH 2.0–6.9. • Coupling EA and HA made up for their respective shortcomings. • Coupling EA and HA transformed more HA into N 2. • Coupling EA and HA broadened the effective pH range up to 6.5. To improve H 2 O 2 generation and Fe3+/Fe2+ cycle simultaneously for enhancing Electro-Fenton performance, the electrode aeration (EA) and hydroxylamine sulfate (HA) were coupled. With dimethyl phthalate (DMP) as main target contaminant, combination of HA and EA greatly accelerated the degradation of DMP and exhibited a synergy in the pH of 2.0–6.9 through promoting the key reactions, including electrochemical two-electron reduction of O 2 into H 2 O 2 and redox cycles of Fe3+/Fe2+, which then improved the generation of hydroxyl radicals (·OH). The coupling EA and HA reduced the use of HA and converted most of HA into environment-friendly N 2 (60.1–62.1% of HA products), while HA/solution aeration(SA) system consumed HA rapidly and the generated N 2 only accounted for 5.8–6.7% of HA products. Furthermore, compared with HA/SA and EA Electro-Fenton systems, enhancement degree of DMP degradation in HA/EA Electro-Fenton process was higher in actual waterbody than in ultrapure water. The coupling EA and HA in the Electro-Fenton process could solve the low Fe3+/Fe2+ cycle efficiency and low H 2 O 2 production simultaneously, and improve the N 2 selectivity of HA transformation, which advanced its application in practical environmental remediation. [Display omitted] [ABSTRACT FROM AUTHOR]