The first step of oxidation of alkylbenzenes by permanganates in acidic aqueous solutions

Rudakov, E. S.; Lobachev, V. L.

doi:10.1007/bf02494695

Cited by 22 publications

(21 citation statements)

References 54 publications

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“…Overall, the EXAFS spectrum of the yellow species is consistent with TcO 3 (OH)(H 2 O) 2 , which can also be described as HTcO 4 To better define the identity of "HTcO 4 " in 12 M H 2 SO 4 , a search for the possible structures was carried out using DFT calculations within the generalized gradient approximation (GGA) and with the Becke 3-parameter, Lee, Yang and Parr (B3LYP) hybrid functional (details in supplemental information). The computed equilibrium geometry of the TcO 3 (OH)(H 2 O) 2 complex with C s symmetry depicted in Figure 3 closely matches structural parameters previously found by XAFS spectroscopy.…”

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confidence: 53%

Speciation of heptavalent technetium in sulfuric acid: structural and spectroscopic studies

et al. 2010

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Summary. The speciation of Tc(VII) in 12 M sulfuric acid was studied by NMR, UVvisible and XAFS spectroscopy, experimental results were supported by DFT calculation and were in agreement with the formation of TcO 3 OH(H 2 O) 2 .Heptavalent transition metal complexes of group VII with the d 0 electronic configuration are often used in catalysis and biomedical applications. [1,2,3] For manganese, the high electron affinity and oxidation potential of its heptavalent complexes make these species the catalysts of choice for oxidation of organic compounds.[4] The chemistry of Re(VII) complexes has been extensively studied, and species with the ReO 3 + core (e.g., CH 3 ReO 3 ) have been reported to be efficient catalysts. [3] Concerning technetium, its coordination chemistry has mainly been driven by radiopharmaceutical applications. Pentavalent and trivalent Tc complexes have been the most studied while heptavalent coordination complexes are still rare. [5] Permetallates with the tetrahedral geometry are the most common heptavalent species and are stable in aqueous media over a large range of pH and electrochemical potential. [6] In concentrated acid, permetallates are generally unstable and reduction, dimerisation, dehydration or complexation can occur. [7,8,9,10] The reaction of pertechnetate in water with strong acid leads to dehydration and various complexes with TcO 3 + core have been synthesized. [11] In theses synthetic reactions, it is assumed that the anhydrous Tc 2 O 7 is formed as an intermediate product. [11] Sulfuric acid is widely used in industrial applications; it is also a solvent of choice for dehydration process. [12-13] Speciation of Mn(VII) in H 2 SO 4 has been documented; manganese heptoxide is formed after dissolution of KMnO 4 and the MnO 3 + cation has been reported. [14,15,16]. For technetium and rhenium, speciation data are still sparse, the HReO 2 (SO 4 ) 2 .3H 2 O complex has been mentioned while technetium heptoxide has been proposed but no structural nor speciation data were provided. [17][18] In the present work, the speciation of technetium complexes after dissolution of KTcO 4 in sulfuric acid has been performed. The molecular structure and spectroscopic properties of the complexes were studied by UV-visible, X-ray absorption fine structure (XAFS) and NMR spectroscopy and density functional theory (DFT) techniques.Potassium pertechnetate (~ 30 mg) was placed in glass vials, and 1 M, 6 M, 12 M sulfuric acid (5 mL) was added with a glass pipette. After dissolution of the salt, a yellow color is observed in 12 M while for 1 M and 6 M, the solution remains clear. UV-visible spectroscopy measurements in 1 M and 6 M show the presence of TcO 4 -while in 12 M, the spectrum of the yellow solution differs from that of the pertechenate (vide supra). The conditions of formation of the yellow species were investigated by NMR spectroscopy. Technetium samples were prepared in H 2 SO 4 (from 3 M to 18 M) and 99 The 99 Tc NMR data were fit by allowing the pK a s and the chemical shifts of the unprot...

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confidence: 53%

Speciation of heptavalent technetium in sulfuric acid: structural and spectroscopic studies

et al. 2010

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“…With respect to the PAHs with alkyl groups (i.e., methylnaphthalene), the mechanism might be similar to that applicable to toluene, ethylbenzene, and xylenes. Permanganate attacked the benzylic C-H bond, followed by the cleavage of benzylic C-H bond, and the observed products were correspondingly benzoic acids, aldehydes, alcohols, or ketones [49,50].…”

Section: Mechanisms Of the Oxidation Of Pharmaceuticals/edcs By Permamentioning

confidence: 99%

Application of permanganate in the oxidation of micropollutants: a mini review

Guan

et al. 2010

Front. Environ. Sci. Eng. China

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As a green oxidant, permanganate has received considerable attention for the removal of micropollutants in drinking water treatment. To provide a better understanding of the oxidation of organic micropollutants with permanganate, the oxidation kinetics of 32 micropollutants were compiled. The pollutants include algal toxins, endocrine disrupting chemicals (EDCs), and pharmaceuticals. The oxidation kinetics of micropollutants by permanganate were found to be first order with respect to both contaminant and permanganate concentrations from which second-order rate constants (k″) were obtained. Permanganate oxidized the heterocyclic aromatics with vinyl moiety (i.e., microcystins, carbamazepine, and dichlorvos) by the addition of double bonds. For the polycyclic aromatic hydrocarbons (PAHs) with alkyl groups, permanganate attacked the benzylic C-H through abstraction of hydrogen. The mechanism for the oxidation of phenolic EDCs by permanganate was a single electron transfer and aromatic ring cleavage. The presence of background matrices could enhance the oxidation of some phenolic EDCs by permanganate, including phenol, chlorinated phenols, bisphenol A, and trichlosan. The toxicity of dichlorvos solution increased after permanganate oxidation, and the estrogenic activity of bisphnol A/estrone increased significantly at the beginning of permanganate oxidation. Therefore, the toxicity of degradation products or intermediates should be determined in the permanganate oxidation processes to better evaluate the applicability of permanganate. The influence of background ions on the permanganate oxidation process is far from clear and should be elucidated in the future studies to better predict the performance of permanganate oxidation of micropollutants. Moreover, methods should be employed to catalyze the permanganate oxidation process to achieve better removal of micropollutants.

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“…The reaction and sorption properties for these cases are shown in Table 1. The reaction rate coefficient for TCE and MnO 4 (Huang et al, 1999) is one order of magnitude higher than for PCE and MnO 4 (Huang et al, 2002), and several orders of magnitude higher than for toluene and MnO 4 (Rudakov and Lobachev, 2000) in order to represent fast, moderately fast, and slow reaction kinetics, respectively (Table 1). The degradation of these contaminants is modeled under fast and slow sorption kinetics, where the sorption rate constants shown in Table 1 are representative of the sorption kinetics occurring in soils with different amounts of organic carbon, as determined in experimental studies (Maraqua, 2001).…”

Section: Resultsmentioning

confidence: 99%

Optimal design of active spreading systems to remediate sorbing groundwater contaminants in situ

Piscopo

Neupauer

Kasprzyk

2016

Journal of Contaminant Hydrology

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The effectiveness of in situ remediation to treat contaminated aquifers is limited by the degree of contact between the injected treatment chemical and the groundwater contaminant. In this study, candidate designs that actively spread the treatment chemical into the contaminant are generated using a multi-objective evolutionary algorithm. Design parameters pertaining to the amount of treatment chemical and the duration and rate of its injection are optimized according to objectives established for the remediation - maximizing contaminant degradation while minimizing energy and material requirements. Because groundwater contaminants have different reaction and sorption properties that influence their ability to be degraded with in situ remediation, optimization was conducted for six different combinations of reaction rate coefficients and sorption rates constants to represent remediation of the common groundwater contaminants, trichloroethene, tetrachloroethene, and toluene, using the treatment chemical, permanganate. Results indicate that active spreading for contaminants with low reaction rate coefficients should be conducted by using greater amounts of treatment chemical mass and longer injection durations relative to contaminants with high reaction rate coefficients. For contaminants with slow sorption or contaminants in heterogeneous aquifers, two different design strategies are acceptable - one that injects high concentrations of treatment chemical mass over a short duration or one that injects lower concentrations of treatment chemical mass over a long duration. Thus, decision-makers can select a strategy according to their preference for material or energy use. Finally, for scenarios with high ambient groundwater velocities, the injection rate used for active spreading should be high enough for the groundwater divide to encompass the entire contaminant plume.

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The first step of oxidation of alkylbenzenes by permanganates in acidic aqueous solutions

Cited by 22 publications

References 54 publications

Speciation of heptavalent technetium in sulfuric acid: structural and spectroscopic studies

Speciation of heptavalent technetium in sulfuric acid: structural and spectroscopic studies

Application of permanganate in the oxidation of micropollutants: a mini review

Optimal design of active spreading systems to remediate sorbing groundwater contaminants in situ

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