Plausible Mechanisms of the Fenton-Like Reactions, M = Fe(II) and Co(II), in the Presence of RCO₂^– Substrates: Are OH^• Radicals Formed in the Process?

DFT calculations concerning the plausible mechanism of Fenton-like reactions catalyzed by Fe­(II) and Co­(II) cations in the presence of carboxylate ligands suggest that hydroxyl radicals are not formed in these reactions. This conclusion suggests that the commonly accepted mechanisms of Fenton-like reactions induced oxidative stress and advanced oxidation processes have to be reconsidered

Acceleration of the corrosion reaction of magnesium by Fenton reagents

<p>Magnesium alloys have attracted increased attention for a variety of applications, chief among which are alternative energy and medical implants. The use of biodegradable implants in the complex system of the human body, in which myriad reactions occur, must consider the potential effects of the body’s natural chemical reactions on implant corrosion rates. The aim of this study was to elucidate the synergistic effects of pure Mg and Mg alloys on the Mg corrosion reaction with reagents that participate in the Fenton reaction. We corroborated our results with six different measurement methods (hydrogen evolution rate [HER], gas chromatography [GC], potentiodynamic polarization, inductively coupled plasma [ICP] spectrometry, Auger electron spectroscopy [AES], and scanning electron microscope [SEM]). The results point out that the corrosion and hydrogen evaluation rates of Mg were elevated by the addition of Fenton reagents, divalent iron and hydrogen peroxide, to a saline solution. In the context of Mg-based alloy medical implant development and use, this observation is significant.</p

The reaction between the peroxide VO(η²-O₂)(pyridine-2-carboxylate)·2H₂O and Fe^II_aq is not a Fenton-like reaction

<p>The reduction of VO(η²-O₂)(pyridine-2-carboxylate) by Fe(H₂O)₆²⁺ proceeds via formation of the transient complex (pyridine-2-carboxylate)(O)V^V(μ-η²: η²-O₂)Fe^II(H₂O)₃²⁺ that is transformed via intramolecular electron transfer into (pyridine-2-carboxylate)(O)V^IV(μ-η²: η²-O₂)Fe^III(H₂O)₃²⁺. The latter transient reacts with another Fe(H₂O)₆²⁺ to yield 2Fe(H₂O)₆³⁺ + V^VO(OH)(pyridine-2-carboxylate)⁺. These results point out that: (1) V^V does not activate the η² bound peroxide toward the Fenton-like reaction. In this aspect, V^V differs from Fe^III in (H₂O)₅Fe–OOH²⁺ and (2) transients of the type L_mMⁿ(μ-η²: η²-O₂)M′L″_l have to be considered in the reductions of complexes of η²-bound peroxides.</p

Polyoxometalates entrapped in sol–gel matrices for reducing electron exchange column applications

<p>Electron exchange columns were developed by utilizing the redox properties of polyoxometalates (POMs) entrapped in silica matrices via the sol–gel route. The properties of the columns strongly depend on the composition of the precursors used to prepare the matrices. The columns exhibit good reversibility and are the first ‘reducing’ electron exchange columns ever prepared. They are also the first columns where both the matrix and the entrapped redox agent are inorganic compounds. This increases their stability. However, the redox properties of the entrapped POMs in the matrices are affected by the composition of the matrices.</p