Enhancement of the degradation of atrazine through CoFe2O4 activated peroxymonosulfate (PMS) process: Kinetic, degradation intermediates, and toxicity evaluation

As an important reactive oxygen species (ROS) with selective oxidation, singlet oxygen (1O2) has wide application prospects in biology and the environment. However, the mechanism of 1O2 formation, especially the conversion of superoxide radicals (·O2-) to 1O2, has been a great controversy. This process is often disturbed by hydroxyl radicals (·OH). Here, we develop a molybdenum cocatalytic Fenton system, which can realize the transformation from ·O2- to 1O2 on the premise of minimizing ·OH. The Mo0 exposed on the surface of molybdenum powder can significantly improve the Fe3+/Fe2+ cycling efficiency and weaken the production of ·OH, leading to the generation of ·O2-. Meanwhile, the exposed Mo6+ can realize the transformation of ·O2- to 1O2. The molybdenum cocatalytic effect makes the conventional Fenton reaction have high oxidation activity for the remediation of organic pollutants and prompts the inactivation of Staphylococcus aureus, as well as the adsorption and reduction of heavy metal ions (Cu2+, Ni2+, and Cr6+). Compared with iron powder, molybdenum powder is more likely to promote the conversion from Fe3+ to Fe2+ during the Fenton reaction, resulting in a higher Fe2+/Fe3+ ratio and better activity regarding the remediation of organics. Our findings clarify the transformation mechanism from ·O2- to 1O2 during the Fenton-like reaction and provide a promising REDOX Fenton-like system for water treatment.

Singlet Oxygen Triggered by Superoxide Radicals in a Molybdenum Cocatalytic Fenton Reaction with Enhanced REDOX Activity in the Environment

Heterogeneous Fenton catalysts: A review of recent advances.

Fenton/Fenton-like processes with in-situ production of hydrogen peroxide/hydroxyl radical for degradation of emerging contaminants: Advances and prospects.

Impact of water matrix on the removal of micropollutants by advanced oxidation technologies

The occurrence of new emerging contaminants in surface waters has recently grabbed increased attention of the scientific community. The adoption of Advanced Oxidation Processes (AOPs) represents an efficient strategy to remove recalcitrant compounds from aqueous streams and achieve high mineralization levels. Amongst AOPs, the photo-Fenton process has been widely investigated due to the possibility of using a renewable energy source (i.e., solar energy) and low concentration of catalyst. On the other hand, the use of photo-Fenton process is restricted to acidic pH values, with associate high operating costs for industrial scale applications. To overcome these drawbacks, photo-Fenton processes modified by adding selected chelating agents can be successfully performed at neutral pH. The present review aims at examining and comparing the most relevant papers dealing with photo-Fenton processes at neutral pH that appeared in the literature so far. Such papers were classified by chelating species adopted. In particular, for each iron(III)-ligand complex, the mechanism of photolysis, the speciation diagram, the light absorption properties, the quantum yields, biodegradation and toxicity, and some example of applications are reported. As a conclusion, suitable criteria for choosing chelating agent and operating conditions in photo-Fenton processes at neutral pH are proposed.

I. Di Somma

Papers

Homogeneous photo-Fenton processes at near neutral pH: A review