Enhancement of the electro-Fenton degradation of organic contaminant by accelerating Fe3+/Fe2+ cycle using hydroxylamine

The Electro-Fenton process can generate reactive oxygen species capable of oxidizing refractory organic contaminants. However, low regeneration efficiency of Fe2+ restricts its application. Herein, hydroxylamine (HA) was added into the Electro-Fenton (HA/Electro-Fenton) process to accelerate the transformation of Fe3+ to Fe2+. Using dimethyl phthalate (DMP) as target contaminant, the HA/Electro-Fenton system alleviated the two-stage reaction process and accelerated the removal of DMP in the pH range of 2.0-6.0. With improving DMP concentration from 5 mg L-1 to 50 mg L-1, their degradation rate increased in the HA/Electro-Fenton system, while decreased in the Electro-Fenton system. The addition of HA had negligible effect on electro-generation of H2O2, but facilitate the redox cycle of Fe3+/Fe2+ and the generation of hydroxyl radicals, thus improving the degradation of DMP. The final transformation products of HA were N-2, N2O, and NO3. The presence of POI improved DMP degradation, while Cl and organic matters inhibited DMP removal in varying degrees. This study provided useful reference to solve the low efficiency of Fe3+/Fe2+ cycle and expand the pH application range in the Electro-Fenton process. (C) 2021 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

Automated summary

The study demonstrated that the addition of hydroxylamine (HA) into the Electro-Fenton process accelerated the transformation of Fe3+ to Fe2+, facilitating the removal of the target organic contaminant. The presence of different ions and organic matters had varying effects on the degradation efficiency, with POI enhancing DMP removal and Cl and organic matters inhibiting it to different extents. Overall, the study provides valuable insights for improving the efficiency of the Fe3+/Fe2+ cycle and expanding the pH application range in Electro-Fenton processes.