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Law JCF, Leung KSY. Redox mediators and irradiation improve fenton degradation of acesulfame. CHEMOSPHERE 2019; 217:374-382. [PMID: 30419391 DOI: 10.1016/j.chemosphere.2018.11.032] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 11/02/2018] [Accepted: 11/03/2018] [Indexed: 06/09/2023]
Abstract
Widely recognized as a promising approach to degrading recalcitrant pollutants, Advanced Oxidation Processes (AOPs) have drawn much attention for their effectiveness and efficiency. Among all the AOPs, the Fenton system has been widely applied for oxidation and mineralization of micropollutants due to its ease of implementation and high catalytic efficiency. However, the necessity of preceding acidification, together with rapid consumption and slow regeneration of Fe(II) resulting in deterioration of reactivity, has reduced its competitiveness as a practical option for water treatment. Acknowledging the above drawbacks, this study investigates the potential viable option to enhance the Fenton system. Acesulfame was chosen as the model compound due to its ubiquitous occurrence and persistence in the environment. UV-assisted photo-Fenton treatment was found to remove the parent compound effectively; the transformation profile of acesulfame was identified and elucidated with the ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry. Prolonged UV photo-Fenton treatment was effective for mineralization of the majority of the transformation products, without increasing the overall toxicity as indicated by Vibrio fischeri bioluminescence assay. The positive effects of the addition of redox mediators to Fenton systems at neutral pH were confirmed in this study. The results could be the basis for further development of homogeneous catalytic degradation techniques for the oxidation of environmental contaminants at circumneutral pHs to neutral pHs.
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Affiliation(s)
- Japhet Cheuk-Fung Law
- Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong Special Administrative Region
| | - Kelvin Sze-Yin Leung
- Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong Special Administrative Region; HKBU Institute of Research and Continuing Education, Shenzhen Virtual University Park, Shenzhen, China; School of Environment, Guangzhou Key Laboratory of Environmental Exposure and Health, Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou, 510632, China.
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2
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Tallent OK, Mailen JC. Study of the Dissolution of Refractory PuO2in Nitric-Hydrofluoric Acid Dissolvents at 100°C. NUCL TECHNOL 2017. [DOI: 10.13182/nt77-a31721] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- O. K. Tallent
- Oak Ridge National Laboratory, Chemical Technology Division P.O. Box X, Oak Ridge, Tennessee 37830
| | - J. C. Mailen
- Oak Ridge National Laboratory, Chemical Technology Division P.O. Box X, Oak Ridge, Tennessee 37830
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Yilmaz G, Lu X, Ho GW. Cross-linker mediated formation of sulfur-functionalized V 2O 5/graphene aerogels and their enhanced pseudocapacitive performance. NANOSCALE 2017; 9:802-811. [PMID: 27982151 DOI: 10.1039/c6nr08233e] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The development of efficient synthesis methods for the preparation of vanadium oxide (V2O5)-graphene holds great promise considering the excellent performance of the composite in electrochemical applications. Herein, we report the cross-linking of a V2O5-graphene hybrid via a vanadium-thiourea redox system, which allowed the assembly of graphene oxide functional groups with V2O5 through the reducing ability of thiourea (TU) under room conditions within an impressively short reaction time (20 min). The resulting 3D composite aerogel forms a highly porous architecture of sulfur-functionalized interconnected networks. Such sulfur-functionalized transition metal oxide-graphene-based aerogels are excellent candidates in energy storage applications. When the vanadium oxide-graphene aerogel was evaluated as an electrode for a supercapacitor, a specific capacitance as high as 484.0 F g-1 at 0.6 A g-1 was obtained in a two-electrode cell configuration. This performance is much higher than that of the vanadium oxide-graphene aerogels prepared in the absence of thiourea. The vanadium oxide-graphene aerogel is able to deliver a remarkable energy density of 43.0 Wh kg-1 at a power density of 0.48 kW kg-1 at 0.6 A g-1 and can hold 24.2 Wh kg-1 at a maximum power density of 9.3 kW kg-1 at 10 A g-1. The symmetric supercapacitor assembled from the aerogel can retain 80% of its initial capacitance after 10 000 cycles.
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Affiliation(s)
- Gamze Yilmaz
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583, Singapore. and Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117585, Singapore
| | - Xianmao Lu
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, China
| | - Ghim Wei Ho
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583, Singapore. and Engineering Science Programme, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore
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Sharma P, Hemkar S, Khandelwal C, Sharma P. Kinetics and Mechanism of Ruthenium(III) Catalyzed Oxidation of Butanone and Uncatalyzed Oxidation of Cychlohexanone by Cerium(IV) in Acid Sulphate Medium. JOURNAL OF THE KOREAN CHEMICAL SOCIETY-DAEHAN HWAHAK HOE JEE 2012. [DOI: 10.5012/jkcs.2012.56.1.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Davies G. Kinetics of Formation and Dissociation of Aquocobalt(III) Complexes with Some Carboxylic Acids in Acid Perchlorate Solution. J Phys Chem B 2007; 111:6955-61. [PMID: 17447812 DOI: 10.1021/jp070848a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The rates of formation and dissociation of monocarboxylic complexes of aquocobalt(III) cations with propionic, malonic, and 2-ethylmalonic acids have been measured with the stopped-flow method over a range of concentrations and temperatures in acid perchlorate media at an ionic strength 3.0 M. Although the rate constants for reactions of CoOHaq2+ with neutral ligands cover only a small range, indicating a dissociative mechanism, the associated activation parameters change cooperatively. These variations are discussed in terms of differences in the structure, proton distribution, and rates of water loss in the ion-pair precursors for the different ligands. Similar activation enthalpies of dissociation indicate a common mode of coordination, and the positive activation entropies for dissociation are consistent with a neutral leaving group.
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Affiliation(s)
- Geoffrey Davies
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115-5000, USA.
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Crawford PW, Ryan MD. Electrochemistry and spectroscopy of sulfate and thiosulfate complexes of iron porphyrins. Inorganica Chim Acta 2002. [DOI: 10.1016/s0020-1693(01)00665-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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7
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Batchelor RJ, Einstein FW, Gay ID, Gu JH, Mehta S, Pinto BM, Zhou XM. Synthesis, characterization, and redox behavior of new selenium coronands and of copper(I) and copper(II) complexes of selenium coronands. Inorg Chem 2000; 39:2558-71. [PMID: 11197010 DOI: 10.1021/ic991345p] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- R J Batchelor
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada
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Batchelor RJ, Einstein FWB, Gay ID, Gu JH, Pinto BM, Zhou XM. Redox chemistry of the selenium coronand, 1,5,9,13-tetraselenacyclohexadecane, and a mechanistic study of the electron transfer reaction of its Cu(II) complex. CAN J CHEM 2000. [DOI: 10.1139/v00-067] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The crystal structure of Cu(16Se4)(SO3CF3)2 (1) shows a centrosymmetric complex having tetragonally distorted octahedral coordination about Cu with trans-axial triflate ligands; CuO 2.464(5) Å. The stereochemistry of the coronand is c,t,c; CuSe 2.4592(9), 2.4553(9) Å. 1: T = 190 K; fw = 845.83; space group P21/n; Z = 2; a = 8.220(2), b = 10.965(4), c = 14.657(5) Å; V = 1273.4 Å3; Rf = 0.037 for 1708 data (Io [Formula: see text] 2.5sigma(Io)) and 152 variables. When recrystallized from MeNO2Et2O 1 undergoes an electron-transfer reaction to give Cu(I) as well as the intermediate radical cation [16Se4]·+ and the stable dication [16Se4]2+. The crystal structure of a mixed MeCNCH2Cl2 solvate of [(16Se4)][SO3CF3]2 (2) revealed the [16Se4]2+ cation which displays two transannular SeSe bonds of 2.5916(15) and 2.6689(15) Å, linking three of the Se atoms in an approximately linear relationship. The central Se atom of this grouping also has a close contact to the fourth Se atom of the molecule of 3.3941(20) Å. 2·solv: T = 195 K; fw = 828; space group P1-; Z = 2; a = 9.015(2), b = 12.850(3), c = 13.835(3) Å; α = 63.98(2), β = 74.71(2), γ = 73.59(2)°; V = 1363.3 Å3; Rf = 0.042 for 2098 data (I0 [Formula: see text] 2.5σ(I0)) and 254 variables. A solid-state 77Se NMR spectrum of 2 shows 4 lines, with isotropic shifts ranging from 173 to 737 ppm. The line widths are all different, and we obtain a tentative assignment by attributing this to differences in dipolar coupling to 19F. Significant differences in chemical shift anisotropy are observed for the various selenium atoms. UV-visible absorption spectroscopy has been used to characterize 1 and its reduction products. 1 absorbs at 560, 464, and 310 nm. Reaction of 1 with the free ligand 16Se4 leads to the disappearance of these peaks, and the growth of a new peak at 320 nm. Oxidation of 16Se4 by NOBF4 produced a transient peak at 320 nm, and subsequently a peak at 256 nm. From the dependence of intensity on 16Se4 concentration, we infer that the former arises from a dimeric species; we assign the lines to the radical cations (16Se4)2+· and 16Se4+·, respectively. Electrochemical studies have been carried out on 1 and on 16Se4. Cyclic voltammetry of 1 shows a two-step reduction to Cu(II)L+· (L = 16Se4) and subsequently to Cu(I)L+. Electrochemical oxidation of 16Se4 leads to 16Se4+· and 16Se42+. Spectroelectrochemical studies showed that oxidation to 16Se4+· gives rise to a band at 256 nm, as seen in chemical oxidation, and at high concentrations a band at 322 nm is also seen, supporting the assignment of this species to the dimeric radical cation. The EPR spectrum of 1 in CH3NO2 solution gave an isotropic g value of 2.053 with hyperfine constants ACuiso = 75 G and ASeiso = 65 G. The low temperature EPR spectrum of 1, measured at -148°C in CH3NO2:toluene (1:1 v/v), gave values of g// = 2.085, ACu// = 160 G; g[Formula: see text] = 2.049, ACu[Formula: see text] = 46 G. An EPR spectrum of 1 in CH3NO2 in the presence of added 16Se4 showed a decrease in intensity of the signals attributable to 1 and the emergence of new signals that are presumed to arise from a species with radical cation character. We have carried out kinetic studies on the reaction between 1 and 16Se4. It is found that the reaction is first order in each of these species, second order overall. The reaction stoichiometry is 2 Cu(16Se4)2+ + 16Se4 –> 2 Cu(16Se4)+ + 16Se42+. These results can be explained by the simple mechanism Cu(II)L2+ + L = L+· + Cu(I)L+, followed by Cu(II)L2+ + L+· –> L2+ + Cu(I)L+. The activation energy is found to be 35 kJ mol-1.Key words: selenium coronands, Cu(II) complex, redox chemistry, mechanism, electron transfer.
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Dubey S, Devra V, Binyahia AR, Sharma PD. Kinetics and mechanism of oxidation of formic acid by bismuth(V) in aqueous phosphoric acid medium. INT J CHEM KINET 2000. [DOI: 10.1002/1097-4601(2000)32:8<491::aid-kin7>3.0.co;2-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Pastor TJ, Antonijević VV, Manojlović DD. Electrogeneration, behaviour and applications of cobalt(III) in perchlorate solutions in acetic acid. Anal Chim Acta 1992. [DOI: 10.1016/0003-2670(92)85209-o] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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A study of the stability of Mn(III) and its redox reaction with Co(II) in aqueous azide medium. Inorganica Chim Acta 1991. [DOI: 10.1016/s0020-1693(00)85384-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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12
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Vincenti M, Minero C, Pramauro E, Pelizzetti E. Kinetics of electron transfer between Ce(IV) nitrate and iron(II) complexes. Inorganica Chim Acta 1985. [DOI: 10.1016/s0020-1693(00)81353-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Hicks KW, Hurless MA. An investigation of the vanadium(V)octacyanomolybdate(VI) reaction. Inorganica Chim Acta 1983. [DOI: 10.1016/s0020-1693(00)81431-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Mentasti E, Baiocchi C. Kinetic determination of alcohols and their binary mixtures with a stopped-flow spectrophotometric technique. Anal Chim Acta 1980. [DOI: 10.1016/s0003-2670(00)00033-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Hanker JS. Osmiophilic reagents in electronmicroscopic histocytochemistry. PROGRESS IN HISTOCHEMISTRY AND CYTOCHEMISTRY 1979; 12:1-85. [PMID: 92799 DOI: 10.1016/s0079-6336(79)80002-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Direct histocytochemical staining methods on undisrupted tissues, stabilized by chemical fixation, potentially offer perhaps the most reliable approach to the study of the enzymes of the cell with relation to its ultrastructure. The atoms which, for the most part, comprise the biomacromolecules and enzymes of cells and tissues contribute little to their inherent electron opacity or ability to scatter electrons differentially. The latter property of a substance is responsible for its observation with the electron microscope. Since the introduction of osmiophilic reagents into cytochemistry (HANKER et al. 1964), the selective deposition of relatively large amounts of polymeric osmium black reaction products at the subcellular sites of insoluble or immobilized enzymes or biomacromolecules has facilitated their demonstration with the light and electron microscopes. Perhaps the most widely employed osmiophilic reagent in histocytochemistry has been DAB which was introduced by GRAHAM and KARNOVSKY (1966a, b). Although it receives its widest use for demonstrating the sites to which the exogenous ultrastructural tracer horseradish peroxidase (HRP) is transported in vertebrate tissues, it is also widely employed for the demonstration of catalase in peroxisomes with the media of FAHIMI (1969) or of NOVIKOFF and GOLDFISCHER (1969), and for the demonstration of cytochrome oxidase with the medium of SELIGMAN et al. (1968a). The importance of this reagent lies in its ability to undergo oxidative polymerization forming an insoluble osmiophilic melanin-like product (HANKER et al. 1972a) which comforms well to ultrastructure, at the sites of enzymic or nonenzyme proteins which catalyze its oxidation. In the past few years, studies in our laboratory have shown that a rational approach to the histocytochemical demonstration of enzymes could be devised. It is based on the selective deposition of transition metal compounds at the sites of enzymes that resemble hemoproteins in their ability to catalyze the oxidative polymerization of DAB. The most useful of these compounds, cupric ferrocyanide (Hatchett's brown) was also introduced into cytochemistry by Karnovsky's laboratory (KARNOVSKY 1964; KARNOVSKY and ROOTS 1974). By the use of natural substrates, when available, or synthetic substrates which liberate or form a reducing agent at the sites of the enzymatic activity, many diverse types of enzymes have been demonstrated by methods depending on this principle known as catalytic osmiophilic polymer generation. DAB has probably been the most useful histocytochemical reagent of the past decade. Yet its borderline carcinogenicity and the frequent interruption of a supply of good quality DAB have encouraged research into a substitute reagent. A new substitute for DAB has resulted from the study of artificial melanins in our laboratory for several years. It consists of a mixture of p-phenylenediamine and pyrocatechol and is much better than DAB for the demonstration of HRP used as a cytochemical tracer...
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Barkin S, Bixon M, Noyes RM, Bar-eli K. On the oxidation of malonic acid by ceric ions. INT J CHEM KINET 1978. [DOI: 10.1002/kin.550100608] [Citation(s) in RCA: 42] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Lande SS, Falk CD, Kochi JK. Cobalt(III) acetate from the ozonation of cobaltous acetate. ACTA ACUST UNITED AC 1971. [DOI: 10.1016/0022-1902(71)80510-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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