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Almansa A, Jardel D, Massip S, Tassaing T, Schatz C, Domergue J, Molton F, Duboc C, Vincent JM. Dual Photoredox Ni/Benzophenone Catalysis: A Study of the Ni II Precatalyst Photoreduction Step. J Org Chem 2022; 87:11172-11184. [PMID: 35946789 DOI: 10.1021/acs.joc.2c01467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The combination of NiIIX2 salts with a bipyridine-type ligand and aromatic carbonyl-based chromophores has emerged as a benchmark precatalytic system to efficiently conduct cross-couplings mediated by light. Mechanistic studies have led to two scenarios in which Ni0 is proposed as the catalytic species. Nonetheless, in none of these studies has a NiII to Ni0 photoreduction been evidenced. By exploiting UV-visible, nuclear magnetic resonance, resonance Raman, electron paramagnetic resonance, and dynamic light scattering spectroscopies and also transmission electron microscopy, we report that, when photolyzed by UVA in alcohols, the structurally defined [NiII2(μ-OH2)(dtbbpy)2(BPCO2)4] complex 1 integrating a benzophenone chromophore is reduced into a diamagnetic NiI dimer of the general formula [NiI2(dtbbpy)2(BPCO2)2]. In marked contrast, in THF, photolysis led to the fast formation of Ni0, which accumulates in the form of metallic ultrathin Ni nanosheets characterized by a mean size of ∼100 nm and a surface plasmon resonance at 505 nm. Finally, it is shown that 1 combined with UVA irradiation catalyzes cross-couplings, that is, C(sp3)-H arylation of THF and O-arylation of methanol. These results are discussed in light of the mechanisms proposed for these cross-couplings with a focus on the oxidation state of the catalytic species.
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Affiliation(s)
- Axel Almansa
- Institut des Sciences Moléculaires (ISM), CNRS UMR 5255, Univ. Bordeaux, 33405 Talence, France
| | - Damien Jardel
- Institut des Sciences Moléculaires (ISM), CNRS UMR 5255, Univ. Bordeaux, 33405 Talence, France
| | - Stéphane Massip
- European Institute of Chemistry and Biology (IECB), Univ. Bordeaux, 33600 Pessac, France
| | - Thierry Tassaing
- Institut des Sciences Moléculaires (ISM), CNRS UMR 5255, Univ. Bordeaux, 33405 Talence, France
| | - Christophe Schatz
- Laboratoire de Chimie des Polymères Organiques (LCPO), CNRS UMR 5629, Univ. Bordeaux, 33607 Pessac Cedex, France
| | - Jérémy Domergue
- Département de Chimie Moléculaire (DCM) CNRS UMR 5250, Univ. Grenoble Alpes, F-38000 Grenoble, France
| | - Florian Molton
- Département de Chimie Moléculaire (DCM) CNRS UMR 5250, Univ. Grenoble Alpes, F-38000 Grenoble, France
| | - Carole Duboc
- Département de Chimie Moléculaire (DCM) CNRS UMR 5250, Univ. Grenoble Alpes, F-38000 Grenoble, France
| | - Jean-Marc Vincent
- Institut des Sciences Moléculaires (ISM), CNRS UMR 5255, Univ. Bordeaux, 33405 Talence, France
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Construction of NiO and Ti3+ self-doped TNTs thin film as a high quantum yield p-n type heterojunction via a novel photoelectrodeposition-assisted anodization method. J Photochem Photobiol A Chem 2021. [DOI: 10.1016/j.jphotochem.2021.113433] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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3
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Sanz-Marco A, Hueso JL, Sebastian V, Nielsen D, Mossin S, Holgado JP, Bueno-Alejo CJ, Balas F, Santamaria J. LED-driven controlled deposition of Ni onto TiO 2 for visible-light expanded conversion of carbon dioxide into C 1-C 2 alkanes. NANOSCALE ADVANCES 2021; 3:3788-3798. [PMID: 36133006 PMCID: PMC9417592 DOI: 10.1039/d1na00021g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 04/20/2021] [Indexed: 06/15/2023]
Abstract
Photocatalytic gas-phase hydrogenation of CO2 into alkanes was achieved over TiO2-supported Ni nanoparticles under LED irradiation at 365 nm, 460 nm and white light. The photocatalysts were prepared using photo-assisted deposition of Ni salts under LED irradiation at 365 nm onto TiO2 P25 nanoparticles in methanol as a hole scavenger. This procedure yielded 2 nm Ni particles decorating the surface of TiO2 with a nickel mass content of about 2%. Before the photocatalytic runs, Ni/TiO2 was submitted to thermal reduction at 400 °C in a 10% H2 atmosphere which induced O-defective TiO2-x substrates. The formation of oxygen vacancies, Ti3+ centers and metallic Ni sites upon photocatalytic CO2 hydrogenation was confirmed by operando EPR analysis. In situ XPS under reaction conditions suggested a strong metal-support interaction and the co-existence of zero and divalent Ni states. These photoactive species enhanced the photo-assisted reduction of CO2 below 300 °C to yield CO, CH4 and C2H6 as final products.
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Affiliation(s)
- Arturo Sanz-Marco
- Department of Chemical and Environmental Engineering, University of Zaragoza c/Mariano Esquillor, s/n; Campus Rio Ebro, Edificio I+D Zaragoza 50018 Spain
- Institute of Nanoscience and Materials of Aragon (INMA), University of Zaragoza, Consejo Superior de Investigaciones Científicas (CSIC) c/Mariano Esquillor, s/n 50018 Zaragoza Spain
| | - José L Hueso
- Department of Chemical and Environmental Engineering, University of Zaragoza c/Mariano Esquillor, s/n; Campus Rio Ebro, Edificio I+D Zaragoza 50018 Spain
- Institute of Nanoscience and Materials of Aragon (INMA), University of Zaragoza, Consejo Superior de Investigaciones Científicas (CSIC) c/Mariano Esquillor, s/n 50018 Zaragoza Spain
- Networking Research Center in Biomaterials, Bioengineering and Nanomedicine (CIBER-BBN) C/Monforte de Lemos, 3-5 28029 Madrid Spain
| | - Víctor Sebastian
- Department of Chemical and Environmental Engineering, University of Zaragoza c/Mariano Esquillor, s/n; Campus Rio Ebro, Edificio I+D Zaragoza 50018 Spain
- Institute of Nanoscience and Materials of Aragon (INMA), University of Zaragoza, Consejo Superior de Investigaciones Científicas (CSIC) c/Mariano Esquillor, s/n 50018 Zaragoza Spain
- Networking Research Center in Biomaterials, Bioengineering and Nanomedicine (CIBER-BBN) C/Monforte de Lemos, 3-5 28029 Madrid Spain
| | - David Nielsen
- Centre for Catalysis and Sustainable Chemistry, Department of Chemistry, Technical University of Denmark Kemitorvet 207 2800 Kgs. Lyngby Denmark
| | - Susanne Mossin
- Centre for Catalysis and Sustainable Chemistry, Department of Chemistry, Technical University of Denmark Kemitorvet 207 2800 Kgs. Lyngby Denmark
| | - Juan P Holgado
- Instituto de Ciencia de Materiales de Sevilla (ICMS, CSIC-University of Seville) Avda. Americo Vespucio, s/n Seville 41092 Spain
| | - Carlos J Bueno-Alejo
- Department of Chemical and Environmental Engineering, University of Zaragoza c/Mariano Esquillor, s/n; Campus Rio Ebro, Edificio I+D Zaragoza 50018 Spain
- Institute of Nanoscience and Materials of Aragon (INMA), University of Zaragoza, Consejo Superior de Investigaciones Científicas (CSIC) c/Mariano Esquillor, s/n 50018 Zaragoza Spain
| | - Francisco Balas
- Department of Chemical and Environmental Engineering, University of Zaragoza c/Mariano Esquillor, s/n; Campus Rio Ebro, Edificio I+D Zaragoza 50018 Spain
- Institute of Nanoscience and Materials of Aragon (INMA), University of Zaragoza, Consejo Superior de Investigaciones Científicas (CSIC) c/Mariano Esquillor, s/n 50018 Zaragoza Spain
- Networking Research Center in Biomaterials, Bioengineering and Nanomedicine (CIBER-BBN) C/Monforte de Lemos, 3-5 28029 Madrid Spain
| | - Jesus Santamaria
- Department of Chemical and Environmental Engineering, University of Zaragoza c/Mariano Esquillor, s/n; Campus Rio Ebro, Edificio I+D Zaragoza 50018 Spain
- Institute of Nanoscience and Materials of Aragon (INMA), University of Zaragoza, Consejo Superior de Investigaciones Científicas (CSIC) c/Mariano Esquillor, s/n 50018 Zaragoza Spain
- Networking Research Center in Biomaterials, Bioengineering and Nanomedicine (CIBER-BBN) C/Monforte de Lemos, 3-5 28029 Madrid Spain
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4
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Gisbertz S, Reischauer S, Pieber B. Overcoming limitations in dual photoredox/nickel-catalysed C–N cross-couplings due to catalyst deactivation. Nat Catal 2020. [DOI: 10.1038/s41929-020-0473-6] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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5
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Wang B, Li X, Wu H, Xu G, Zhang X, Shu X, Lv J, Wu Y. Synthesis of Ni−MoS
x
/g‐C
3
N
4
for Photocatalytic Hydrogen Evolution under Visible Light. ChemCatChem 2019. [DOI: 10.1002/cctc.201901654] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Bo Wang
- School of Materials Science and EngineeringHefei University of Technology Hefei 230009 P. R. China
| | - Xia Li
- School of Materials Science and EngineeringHefei University of Technology Hefei 230009 P. R. China
| | - Haining Wu
- School of Materials Science and EngineeringHefei University of Technology Hefei 230009 P. R. China
| | - Guangqing Xu
- School of Materials Science and EngineeringHefei University of Technology Hefei 230009 P. R. China
- Key Laboratory of Advanced Functional Materials and Devices of Anhui Province Hefei 230009 P. R. China
| | - Xinyi Zhang
- Collaborative Innovation Centre for Sustainable Energy Materials Guangxi Key Laboratory of Electrochemical Energy MaterialsGuangxi University Nanning 530004 P. R. China
| | - Xia Shu
- School of Materials Science and EngineeringHefei University of Technology Hefei 230009 P. R. China
- Key Laboratory of Advanced Functional Materials and Devices of Anhui Province Hefei 230009 P. R. China
| | - Jun Lv
- School of Materials Science and EngineeringHefei University of Technology Hefei 230009 P. R. China
- Key Laboratory of Advanced Functional Materials and Devices of Anhui Province Hefei 230009 P. R. China
| | - Yucheng Wu
- School of Materials Science and EngineeringHefei University of Technology Hefei 230009 P. R. China
- Key Laboratory of Advanced Functional Materials and Devices of Anhui Province Hefei 230009 P. R. China
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Trivedi NS, Mandavgane SA. Fundamentals of 2, 4 Dichlorophenoxyacetic Acid Removal from Aqueous Solutions. SEPARATION AND PURIFICATION REVIEWS 2018. [DOI: 10.1080/15422119.2018.1450765] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Nikhilesh S. Trivedi
- Chemical Engineering Department, Visvesvaraya National Institute of Technology, Nagpur, India
| | - Sachin A. Mandavgane
- Chemical Engineering Department, Visvesvaraya National Institute of Technology, Nagpur, India
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7
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Wu K, Zhang F, Wu H, Wei C. The mineralization of oxalic acid and bio-treated coking wastewater by catalytic ozonation using nickel oxide. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:2389-2400. [PMID: 29124641 DOI: 10.1007/s11356-017-0597-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 10/24/2017] [Indexed: 06/07/2023]
Abstract
Coking wastewater after biological treatment still possesses potential environmental risk and should be mineralized further. This work focused on the mineralization of bio-treated coking wastewater using catalytic ozonation by NiO. First, oxalic acid, the typical by-product of advanced oxidation process (AOPs), was used to test the catalytic performance of NiOs, prepared by modified hydrothermal methods upon addition of different surfactants. This demonstrated that NiO upon addition of hexadecyltrimethylammonium (CTAB) had the best catalytic activity, due to its high concentration surface hydroxyl density and strong stability. Moreover, the best NiO was applied for the catalytic ozonation of bio-treated coking wastewater. Under our experimental conditions, the total organic carbon (TOC) removal reached 100% after 420 min. In addition, the spectroscopic analysis suggested that compounds with conjugated structures could be significantly removed by both ozonation and catalytic ozonation. Some of these substances were transformed into by-products with aliphatic C-C and O=C-O groups such as organic acids that can inhibit further mineralization.
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Affiliation(s)
- Kaiyi Wu
- School of Environment and Energy, South China University of Technology, 382 Waihuan East Road, Guangzhou Higher Education Mega Center, Guangzhou, 510006, China
| | - Fengzhen Zhang
- School of Environment and Energy, South China University of Technology, 382 Waihuan East Road, Guangzhou Higher Education Mega Center, Guangzhou, 510006, China
| | - Haizhen Wu
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, People's Republic of China
| | - Chaohai Wei
- School of Environment and Energy, South China University of Technology, 382 Waihuan East Road, Guangzhou Higher Education Mega Center, Guangzhou, 510006, China.
- The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou, 510006, People's Republic of China.
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8
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Aguilar CM, Rodríguez JL, Chairez I, Tiznado H, Poznyak T. Naphthalene degradation by catalytic ozonation based on nickel oxide: study of the ethanol as cosolvent. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2017; 24:25550-25560. [PMID: 26832864 DOI: 10.1007/s11356-016-6134-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 01/19/2016] [Indexed: 06/05/2023]
Abstract
Naphthalene (NA) is a polycyclic aromatic hydrocarbon with toxic properties in aquatic systems. Ozonation (O3) and catalytic ozonation (O3-cat) processes are attractive alternatives of degradation for this kind of compound. NA (20 mg L-1) degradation by conventional and catalytic ozonation in the presence of a cosolvent (ethanol) was the aim of this study. This solution was proposed to simulate some aspects of real wastewaters where not only water acts as solvent. Two proportions of the mixture ethanol/water were selected (30:70 and 50:50) with the purpose of studying the cosolvent effect on NA degradation system by ozonation. O3-cat process used nickel oxide as catalyst (0.1 g L-1). The degradation analysis of NA by O3-cat in two different proportions of cosolvent showed that in the case of 30:70 (ethanol/water), a 95 % of NA elimination in 60 min was obtained, while in the case 50:50 (ethanol/water), only 55 % was achieved. The O3 process showed similar results of degradation to the initial compound in comparison with catalytic system. According to these results, there is an inhibition effect in pollutant removal by ethanol due to the higher ethanol concentration; the lower elimination rate of NA was obtained (by 40 % during the 60 min). The by-products analysis of ozonation process detected oxalic and formic acids. Treatments with NiO presented less production of organic acids in comparison with conventional ozonation process. The high concentration of ethanol has a relevant factor in the elimination of NA and formation of organic acids; samples with 50 % of cosolvent have showed a higher concentration of organic acids. X-ray photoelectron spectroscopy (XPS) study of O3-cat of diluent (O3-NiO control) and O3-NA-NiO showed the presence of -CO3 absorbed on catalyst due to ethanol decomposition.
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Affiliation(s)
- C Marissa Aguilar
- Departamento de Bioprocesos, UPIBI-Instituto Politécnico Nacional, Ticoman, 07340, México, D.F., México
| | - Julia L Rodríguez
- Lab. Ing. Química Ambiental, ESIQIE-Instituto Politécnico Nacional, Zacatenco, 07738, México, D.F., México.
| | - Isaac Chairez
- Departamento de Bioprocesos, UPIBI-Instituto Politécnico Nacional, Ticoman, 07340, México, D.F., México
| | - Hugo Tiznado
- Universidad Nacional Autónoma de México, Centro de Nanociencias y Nanotecnología, Km. 107 Carretera Tijuana a Ensenada, 22860, Ensenada, Baja California, México
| | - Tatyana Poznyak
- Lab. Ing. Química Ambiental, ESIQIE-Instituto Politécnico Nacional, Zacatenco, 07738, México, D.F., México
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9
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Bradu C, Magureanu M, Parvulescu VI. Degradation of the chlorophenoxyacetic herbicide 2,4-D by plasma-ozonation system. JOURNAL OF HAZARDOUS MATERIALS 2017; 336:52-56. [PMID: 28472708 DOI: 10.1016/j.jhazmat.2017.04.050] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 04/19/2017] [Accepted: 04/20/2017] [Indexed: 05/16/2023]
Abstract
A novel advanced oxidation process based on the combination of ozonation with non-thermal plasma generated in a pulsed corona discharge was developed for the oxidative degradation of recalcitrant organic pollutants in water. The pulsed corona discharge in contact with liquid, operated in oxygen, produced 3.5mgL-1 ozone, which was subsequently introduced in the ozonation reactor. The solution to be treated was continuously circulated between the plasma reactor and the ozonation reactor. The system was tested for the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) and considerably improved performance as compared to ozonation alone, both with respect to the removal of the target compound and to mineralization. The apparent reaction rate constant for 2,4-D removal was 0.195min-1, more than two times higher than the value obtained in ozonation experiments. The mineralization reached more than 90% after 60min treatment and the chlorine balance confirms the absence of quantifiable amounts of chlorinated by-products. The energy efficiency was considerably enhanced by shortening the duration of the discharge pulses, which opens the way for further optimization of the electrical circuit design.
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Affiliation(s)
- C Bradu
- University of Bucharest, Faculty of Biology, Department of Systems Ecology and Sustainability, Splaiul Independentei 91-95, 050095, Bucharest, Romania
| | - M Magureanu
- National Institute for Lasers, Plasma and Radiation Physics, Department of Plasma Physics and Nuclear Fusion, Atomistilor Str. 409, P.O. Box MG-36, 077125, Magurele, Bucharest, Romania.
| | - V I Parvulescu
- University of Bucharest, Faculty of Chemistry, Department of Organic Chemistry, Biochemistry and Catalysis, Bd. Regina Elisabeta 4-12, 030016, Bucharest, Romania
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McTiernan CD, Leblanc X, Scaiano JC. Heterogeneous Titania-Photoredox/Nickel Dual Catalysis: Decarboxylative Cross-Coupling of Carboxylic Acids with Aryl Iodides. ACS Catal 2017. [DOI: 10.1021/acscatal.6b03687] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Christopher D. McTiernan
- Department of Chemistry and Biomolecular Sciences and Centre for Catalysis Research and Innovation, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N 6N5, Canada
| | - Xavier Leblanc
- Department of Chemistry and Biomolecular Sciences and Centre for Catalysis Research and Innovation, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N 6N5, Canada
| | - Juan C. Scaiano
- Department of Chemistry and Biomolecular Sciences and Centre for Catalysis Research and Innovation, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N 6N5, Canada
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11
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Zhu S, Zhang P, Chang L, Zhong Y, Wang K, Shao H, Wang J, Zhang J, Cao CN. Photochemical fabrication of 3D hierarchical Mn3O4/H-TiO2 composite films with excellent electrochemical capacitance performance. Phys Chem Chem Phys 2016; 18:8529-36. [DOI: 10.1039/c6cp00372a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
We report a novel photodeposition strategy for the fabrication of 3D hierarchical Mn3O4/H-TiO2 composite films with prominent pseudocapacitive performance.
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Affiliation(s)
- Shasha Zhu
- Department of Chemistry
- Zhejiang University
- Hangzhou 310027
- P. R. China
| | - Peipei Zhang
- Department of Chemistry
- Zhejiang University
- Hangzhou 310027
- P. R. China
| | - Ling Chang
- Department of Chemistry
- Zhejiang University
- Hangzhou 310027
- P. R. China
| | - Yuan Zhong
- Department of Chemistry
- Zhejiang University
- Hangzhou 310027
- P. R. China
| | - Kai Wang
- Department of Chemistry
- Zhejiang University
- Hangzhou 310027
- P. R. China
| | - Haibo Shao
- Department of Chemistry
- Zhejiang University
- Hangzhou 310027
- P. R. China
| | - Jianming Wang
- Department of Chemistry
- Zhejiang University
- Hangzhou 310027
- P. R. China
| | - Jianqing Zhang
- Department of Chemistry
- Zhejiang University
- Hangzhou 310027
- P. R. China
| | - Chu-nan Cao
- Department of Chemistry
- Zhejiang University
- Hangzhou 310027
- P. R. China
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12
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Rodríguez JL, Valenzuela MA, Tiznado H, Poznyak T, Flores E. Synthesis of nickel oxide nanoparticles supported on SiO2 by sensitized liquid phase photodeposition for applications in catalytic ozonation. ACTA ACUST UNITED AC 2014. [DOI: 10.1016/j.molcata.2014.04.028] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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13
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Rodríguez JL, Valenzuela MA, Poznyak T, Lartundo L, Chairez I. Reactivity of NiO for 2,4-D degradation with ozone: XPS studies. JOURNAL OF HAZARDOUS MATERIALS 2013; 262:472-481. [PMID: 24076483 DOI: 10.1016/j.jhazmat.2013.08.041] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 08/15/2013] [Accepted: 08/16/2013] [Indexed: 06/02/2023]
Abstract
2,4-Dichlorophenoxyacetic acid (2,4-D) is usually used as a refractory model compound that requires a prolonged reaction time for mineralization. In this study, we found that nickel oxide (NiO) significantly improved 2,4-D degradation and mineralization in reaction with ozone. Other metal oxides, such as titania, silica and alumina, were also tested in this reaction, so that, the mineralization degree was almost the same for all of them (ca. 25%), whereas NiO showed more than 60% in 1h. These outstanding results led us to study in more depth the role of NiO as catalyst in the degradation of 2,4-D. For instance, the optimum NiO loading amount was 0.3 g L(-1). The catalytic ozonation showed a high stability after three reaction cycles. With the aim of identifying the surface species responsible for the high activity of NiO, besides knowing the byproducts during the degradation of 2,4-D, XPS and HPLC were mainly used as analytical tools. According to the results, the mineralization of 2,4-D was directly influenced by the adsorbed chlorate organic compounds and oxalate group onto NiO. Therefore, NiO plays a true role as a catalyst forming surface compounds which are subsequently decomposed causing an increase in the mineralization efficiency. In addition, it was possible to identify several degradation byproducts (2,4-diclorophenol, glycolic, fumaric, maleic and oxalic acids) that were included in a rational reaction pathway. It was proposed that 2,4-D elimination in presence of NiO as catalyst is a combination of processes such as: conventional ozonation, indirect mechanism (OH) and surface complex formation.
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Affiliation(s)
- Julia L Rodríguez
- Lab. de Ing. Química Ambiental, ESIQIE - Instituto Politécnico Nacional, Zacatenco, 07738 Mexico, D.F., Mexico; Lab. Catálisis y Materiales, ESIQIE - Instituto Politécnico Nacional, Zacatenco, 07738 Mexico, D.F., Mexico.
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