Oxidation of emerging organic contaminants by in-situ H2O2 fenton system

The existence and risk of emerging organic contaminants (EOCs) have been under consideration and paid much effort to degrade these pollutants. Fenton system is one of the most widely used technologies to solve this problem. The original Fenton system relies on the hydroxyl radicals produced by Fe(II)/H2O2 to oxidize the organic contaminants. However, the application of the Fenton system is limited by its low iron cycling efficiency and the high risks of hydrogen peroxide transportation and storage. The introduction of external energy (including light and electricity etc.) can effectively promote the Fe(III)/Fe(II) cycle and the reduction of oxygen to produce hydrogen peroxide in situ. This review introduces three in-situ Fenton systems, which are electro-Fenton, Photo-Fenton, and chemical reaction. The mechanism, influencing factors, and catalysts of these three in-situ Fenton systems in degrading EOCs are discussed systematically. This review strengthens the understanding of Fenton and in-situ Fenton systems in degradation, offering further insight into the real application of the in-situ Fenton system in the removal of EOCs. [Display omitted] •The mechanisms and influencing factors of in-situ Fenton systems are summarized.•The different EOCs oxidation mechanisms by in-situ Fenton systems are reviewed.•Electrode materials affect mechanism and efficiency of in-situ Fenton system.•Iron-based compounds are beneficial to photo-generation and utilization of H2O2.•Catalysts with electron-rich and electron-poor areas efficiently product H2O2.