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Nature's Response to Land Contamination
Published in Daniel T. Rogers, Environmental Compliance Handbook, 2023
In reduction–oxidation degradation reactions (redox), electrons are transferred from one atom to another. Chemical reduction is defined as the addition of electrons, and chemical oxidation is defined as the loss of electrons (Hemond and Fechner-Levy 2000). In a reaction involving atoms A and B, if atom A gains an electron, it is reduced, and atom B, having donated an electron, is the reductant. Because atom B loses an electron, B is oxidized, and atom A is the oxidant. Each reaction involving the loss or gain of an electron is termed a half reaction. The oxidation of contaminants can occur very rapidly through combustion or incineration. Here, fire transforms the contaminants through oxidation at greatly elevated temperatures and uses the cooking, heating, and transportation applications (Hemond and Fechner-Levy 2000).
Water and the Science of Pollution
Published in Daniel T. Rogers, Environmental Compliance Handbook, 2023
In reduction–oxidation degradation reactions (redox), electrons are transferred from one atom to another. Chemical reduction is defined as the addition of electrons, and chemical oxidation is defined as the loss of electrons (Hemond and Fechner-Levy 2000). In a reaction involving atoms A and B, if atom A gains an electron, it is reduced, and atom B, having donated an electron, is the reductant. Because atom B loses an electron, B is oxidized, and atom A is the oxidant. Each reaction involving the loss or gain of an electron is termed a half reaction. The oxidation of contaminants can occur very rapidly through combustion or incineration. Here, fire transforms the contaminants through oxidation at greatly elevated temperatures and uses the cooking, heating, and transportation applications (Hemond and Fechner-Levy 2000).
The Behavior of Pollution in Nature
Published in Daniel T. Rogers, Environmental Compliance and Sustainability, 2019
In reduction–oxidation degradation reactions (redox), electrons are transferred from one atom to another. Chemical reduction is defined as the addition of electrons and chemical oxidation is defined as the loss of electrons (Hemond and Fechner-Levy 2000). In a reaction involving Atoms A and B, if Atom A gains an electron, it is reduced, and Atom B, having donated an electron, is the reductant. Because Atom B loses an electron, B is oxidized and Atom A is the oxidant. Each reaction involving the loss or gain of an electron is termed a half-reaction. The oxidation of contaminants can occur very rapidly through combustion or incineration. Here, fire transforms the contaminants through oxidation at greatly elevated temperatures and uses the cooking, heating, and transportation applications (Hemond and Fechner-Levy 2000).
The impact of non-uniformity and resistivity on the homogenised corrosion parameters of rebars in concrete – a circuit model analysis
Published in Corrosion Engineering, Science and Technology, 2023
Gang Li, Richard Evitts, Moh Boulfiza
Despite the mathematical similarity of the Butler–Volmer equation when applied to either a single electrode with a reversible half-cell reaction or a mixed electrode reaction, there is a distinctly different meaning of the net current density, . Taking the corrosion of steel for example, with the reversible half-reaction (), in Equation (1) represents the total change of iron (either dissolution or deposition), dissolution case shown in Figure 1(a). However, in a mixed electrode reaction (Figure 1(b)), when polarised anodically from its equilibrium potential, in Equation (2) does not include all the change of iron: the ‘internal current’, also contributes to a portion of the total change of iron . This contribution could be significant when the anodic polarisation overpotential is small, which implies a non-negligible coexisting macro-cell (net current) and micro-cell corrosion (internal current). Experimental observations [12] have indicated the micro-cell contribution in a seemingly macro-cell-dominant corrosion could be significant. This is especially true when the macro-cell current density is low due to small potential differences between the neighbouring rebar segments.
Vibrational spectroscopy of free di-manganese oxide cluster complexes with di-hydrogen
Published in Molecular Physics, 2023
Sandra M. Lang, Thorsten M. Bernhardt, Joost M. Bakker, Bokwon Yoon, Uzi Landman
The direct conversion of solar energy into storable and renewable fuels is one of the main challenges of modern catalysis research. Inspired by natural photosynthesis, sun-light driven water oxidation followed by the hydrogen evolution reaction (HER, i.e. proton reduction) has attracted much interest and huge research efforts have been invested in this direction during the past decade (see e.g. Ref. [1–7] for recent review articles). Among the various processes involved in artificial photosynthesis the catalysis of the energy demanding water oxidation (reaction 1) represents one of the main challenges (see e.g. Ref. [1,6–10]). In nature, this half-reaction (i.e. the oxidative part of the water plus carbon dioxide redox reaction) is catalysed by the oxygen evolving complex (OEC), which is embedded in the protein structure of photosystem II (PS II). X-ray diffraction studies revealed that the OEC consists of an inorganic CaMn4O5 cluster surrounded by a network of amino acid residues and water molecules [11,12].
Carbon dots/polyoxometalate/Pt as a ternary composite for electrocatalytic methanol oxidation
Published in Journal of Coordination Chemistry, 2020
Shuang Han, Xiao-Jing Sang, Jian-Sheng Li, Wan-Sheng You
Direct methanol fuel cells (DMFCs) have attracted attention by scientists as an ideal new energy conversion system [1]. In DMFCs, the methanol oxidation reaction (MOR) is the anode half reaction, and the performance of the anode catalyst is always critical to the overall efficiency of the fuel cell. At present, the electrocatalytic oxidation of methanol is slow even employing platinum (Pt)-based catalyst, more importantly, the intermediate products in MOR (mainly CO) will poison Pt and reduce the stability of the cell [2]. Therefore, for large-scale application of high efficiency DMFCs, development of new catalysts for MOR is still the focus in this field. A large amount of research has been done including optimization of carrier materials [3], construction of Pt-based bimetallic catalysts such as PtRu [4], PtSn [5], etc., and construction of Pt-based multifunctional catalysts such as Pt/SnO2 [6], Pt/WO3 [7], Pt/MoOx [8], etc. Achievements have been made to overcome the poisoning of Pt, reduce the dosage of Pt and improve the activity of catalysts to a certain extent. Recently, some Pt-free catalysts such as SnO2/m-ZSM-5 [9], CeO2/Nano-ZSM-5 [10], NiO [11] and NiCo/NiO-CoO/NPCC [12] have been developed for MOR, but these catalysts are mainly used in alkaline media, and Pt-based materials are still recognized as necessary electrocatalysts in acidic media. Hence, new methods to further improve the catalytic activity and stability of Pt catalysts are still needed in this important field.