Kinetic, Mechanistic and Spectral Investigation of Ruthenium(III) Catalysed Oxidation of Atenolol by Alkaline Diperiodatonickelate(IV) (Stopped Flow Technique)

Enhanced oxidation of organic contaminants by Mn(VII) in water

Studies that promote chemical oxidation by permanganate (MnO₄^-; Mn(VII)) as a viable technology for water treatment and environmental purification have been quickly accumulating over the past decades. Various methods to activate Mn(VII) have been proposed and their efficacy in destructing a wide range of emerging organic contaminants has been demonstrated. This article aims to present a state-of-art review on the development of Mn(VII) activation methods, including photoactivation, electrical activation, the addition of redox mediators, carbonaceous materials, and other chemical agents, with a particular focus on the potential activation mechanism and critical influencing factors. Different reaction mechanisms are involved in activated Mn(VII) oxidation processes, including the generation of reactive intermediates derived from Mn(VII) (e.g., Mn(III), Mn(V), and Mn(VI)) or activators (e.g., intermediates of redox mediators and Ru catalysts), reactive oxygen species (ROS) (e.g., •OH, O₂^•-, and ¹O₂), as well as electron transfer from organics to Mn(VII) via catalysts as the electron mediator. Except •OH that is generated as one of co-oxidants in UV/Mn(VII) process, other reactive species are relatively mild oxidants, which are more selective toward organic substrates and highly tolerant toward various water matrices (e.g., inorganic ions and natural organic matter) compared to strongly oxidizing radical species. Therefore, activated Mn(VII) oxidation processes show a good prospect for efficient removal of target contaminants in natural and complex environmental matrices. However, there are some disputes about the dominant reactive species generated in these processes, and their identification methods may be not appropriate, causing serious confusion in the mechanistic understanding. So, further efforts are still needed to fill the knowledge gap and also to address the application challenges of these technologies.

Ruthenium nanoparticles supported on CeO2 for catalytic permanganate oxidation of butylparaben

This study developed a heterogeneous catalytic permanganate oxidation system with ceria supported ruthenium, Ru/CeO2 (0.8‰ as Ru), as catalyst for the first time. The catalytic performance of Ru/CeO2 toward butylparaben (BP) oxidation by permanganate was strongly dependent on its dosage, pH, permanganate concentration and temperature. The presence of 1.0 g L(-1) Ru/CeO2 increased the oxidation rate of BP by permanganate at pH 4.0-8.0 by 3-96 times. The increase in Ru/CeO2 dosage led to a progressive enhancement in the oxidation rate of BP by permanganate at neutral pH. The XANES analysis revealed that (1) Ru was deposited on the surface of CeO2 as Ru(III); (2) Ru(III) was oxidized by permanganate to its higher oxidation state Ru(VI) and Ru(VII), which acted as the co-oxidants in BP oxidation; (3) Ru(VI) and Ru(VII) were reduced by BP to its initial state of Ru(III). Therefore, Ru/CeO2 acted as an electron shuttle in catalytic permanganate oxidation process. LC-MS/MS analysis implied that BP was initially attacked by permanganate or Ru(VI) and Ru(VII) at the aromatic ring, leading to the formation of various hydroxyl-substituted and ring-opening products. Ru/CeO2 could maintain its catalytic activity during the six successive runs. In conclusion, catalyzing permanganate oxidation with Ru/CeO2 is a promising technology for degrading phenolic pollutants in water treatment.

Experimental study on elemental mercury removal by diperiodatonickelate (IV) solution

A novel method has been developed to remove elemental mercury from simulated flue gas by a diperiodatonickelate (IV) solution. The influencing factors, such as diperiodatonickelate (IV) concentration, reaction temperature, solution pH, the initial Hg(0) concentration, SO₂ concentration and NO concentration were investigated at a bubbling reactor. In the presence of SO₂ and NO, removal efficiency of 86.2% for elemental mercury was obtained. Meanwhile, 56.2% of NO and 98% of SO₂ were simultaneously removed, under the optimal experimental conditions, in which diperiodatonickelate (IV) concentration was 6 × 10(-3)mol/L, reaction temperature was 50°C, the initial Hg(0) concentration was 20 μg/m(3) and pH was 8.5. Moreover, based on the research results of the hydrolyzing products of IO(4-), and the analysis of the removal products of Hg(0), the reaction mechanism of Hg(0) removal was proposed.

Kinetics and Mechanism of Oxidation of Gabapentin (Neurontin) Anion by Alkaline Diperiodatonickelate(IV) — A Free Radical Intervention

The kinetics of oxidation of gabapentin (Neurontin) (GP) by diperiodatonickelate(IV) (DPN) in aqueous alkaline medium was studied spectrophotometrically. The reaction is first order with respect to [DPN] and is an apparent less than unit order, each in [GP] and [alkali] under the experimental conditions. Reaction rate increases with increase in ionic strength and in solvent polarity of the medium. Addition of reaction products has no effect on the reaction rate. A mechanism involving the formation of a complex between the oxidant and substrate has been proposed. The products are identified by spot test, IR and NMR studies. The reaction constants involved in the mechanism were evaluated. There is a good agreement between the observed and calculated rate constants under varying experimental conditions. The activation parameters with respect to the slow step of scheme were evaluated and discussed.