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Chen C, Zhao S, Tang X, Yi H, Gao F, Yu Q, Liu J, Wang W, Tang T, Meng X. δ-MnO 2 decorated layered double oxides in-situ grown on nickel foam towards electrothermal catalysis of n-heptane. J Environ Sci (China) 2023; 126:308-320. [PMID: 36503759 DOI: 10.1016/j.jes.2022.03.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 02/20/2022] [Accepted: 03/09/2022] [Indexed: 06/17/2023]
Abstract
Energy-saving and efficient monolithic catalysts are hotspots of catalytic purification of industrial gaseous pollutants. Here, we have developed an electrothermal catalytic mode, in which the ignition temperature required for the reaction is provided by Joule heat generated when the current flows through the catalyst. In this paper, Mn/NiAl/NF, Mn/NiFe/NF and Mn/NF metal-based monolithic catalysts were prepared using nickel foam (NF) as the carrier for thermal and electrothermal catalysis of n-heptane. The results indicated that Mn-based monolithic catalysts exhibit high activity in thermal and electrothermal catalysis. Mn/NiFe/NF achieve conversion of n-heptane more than 99% in electrothermal catalysis under a direct-current (DC) power of 6 W, and energy-saving is 54% compared with thermal catalysis. In addition, the results indicated that the introduction of NiAl (or NiFe) greatly enhanced the catalytic activity of Mn/NF, which attributed to the higher specific surface area, Mn3+/Mn4+, Ni3+/Ni2+, adsorbed oxygen species (Oads)/lattice oxygen species (Olatt), redox performance of the catalyst. Electrothermal catalytic activity was significantly higher than thermal catalytic activity before complete conversion, which may be related to electronic effects. Besides, Mn/NiFe/NF has good cyclic and long-term stability in electrothermal catalysis. This paper provided a theoretical basis for applying electrothermal catalysis in the field of VOCs elimination.
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Affiliation(s)
- Chaoqi Chen
- Department of Environmental Engineering, School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Shunzheng Zhao
- Department of Environmental Engineering, School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China
| | - Xiaolong Tang
- Department of Environmental Engineering, School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China
| | - Honghong Yi
- Department of Environmental Engineering, School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China.
| | - Fengyu Gao
- Department of Environmental Engineering, School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China
| | - Qingjun Yu
- Department of Environmental Engineering, School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China
| | - Jun Liu
- Department of Environmental Engineering, School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China
| | - Weixiao Wang
- Department of Environmental Engineering, School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Tian Tang
- Department of Environmental Engineering, School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Xianzheng Meng
- Department of Environmental Engineering, School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China
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Sun X, Li C, Yu B, Wang J, Wang W. Removal of gaseous volatile organic compounds via vacuum ultraviolet photodegradation: Review and prospect. J Environ Sci (China) 2023; 125:427-442. [PMID: 36375926 DOI: 10.1016/j.jes.2022.01.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 01/10/2022] [Accepted: 01/17/2022] [Indexed: 06/16/2023]
Abstract
Volatile organic compounds (VOCs) have attracted much attention for decades as they are the precursors of photochemical smog and are harmful to the environment and human health. Vacuum ultraviolet (VUV) photodegradation is a simple and effective method to decompose VOCs (ranging from tens to hundreds of ppmV) without additional oxidants or catalysts in the air at atmospheric pressure. In this paper, we review the research progress of VOCs removal via VUV photodegradation. The fundamentals are outlined and the key operation factors for VOCs degradation, such as humidity, oxygen content, VOCs initial concentration, light intensity, and flow rate, are discussed. VUV photodegradation of VOCs mixture is elucidated. The application of VUV photodegradation in combination with ozone-assisted catalytic oxidation (OZCO) and photocatalytic oxidation (PCO) systems, and as the pre-treatment technique for biological purification are illustrated. Based on the summary, we propose the challenges of VUV photodegradation and perspectives for its future development.
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Affiliation(s)
- Xue Sun
- School of Civil and Environmental Engineering, Harbin Institute of Technology, Shenzhen 518055, China
| | - Chaolin Li
- School of Civil and Environmental Engineering, Harbin Institute of Technology, Shenzhen 518055, China.
| | - Boping Yu
- Shenzhen Academy of Environmental Sciences, Shenzhen 518001, China
| | - Jingwen Wang
- School of Civil and Environmental Engineering, Harbin Institute of Technology, Shenzhen 518055, China
| | - Wenhui Wang
- School of Civil and Environmental Engineering, Harbin Institute of Technology, Shenzhen 518055, China.
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Zhang X, Guo Z, Sun P, Liu X, Luo Z, Li J, Zhang D, Xu X. Removal of unsymmetrical dimethylhydrazine: A critical review with particular focus on photocatalytic oxidation. Sep Purif Technol 2023. [DOI: 10.1016/j.seppur.2023.123425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
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4
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Kim J, Choe YJ, Kim SH, Choi IS, Jeong K. Deciphering Evolution Pathway of Supported NO 3 • Enabled via Radical Transfer from •OH to Surface NO 3 - Functionality for Oxidative Degradation of Aqueous Contaminants. JACS AU 2021; 1:1158-1177. [PMID: 34467355 PMCID: PMC8397361 DOI: 10.1021/jacsau.1c00124] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Indexed: 06/13/2023]
Abstract
NO3 • can compete with omnipotent •OH/SO4 •- in decomposing aqueous pollutants because of its lengthy lifespan and significant tolerance to background scavengers present in H2O matrices, albeit with moderate oxidizing power. The generation of NO3 •, however, is of grand demand due to the need of NO2 •/O3, radioactive element, or NaNO3/HNO3 in the presence of highly energized electron/light. This study has pioneered a singular pathway used to radicalize surface NO3 - functionalities anchored on polymorphic α-/γ-MnO2 surfaces (α-/γ-MnO2-N), in which Lewis acidic Mn2+/3+ and NO3 - served to form •OH via H2O2 dissection and NO3 • via radical transfer from •OH to NO3 - (•OH → NO3 •), respectively. The elementary steps proposed for the •OH → NO3 • route could be energetically favorable and marginal except for two stages such as endothermic •OH desorption and exothermic •OH-mediated NO3 - radicalization, as verified by EPR spectroscopy experiments and DFT calculations. The Lewis acidic strength of the Mn2+/3+ species innate to α-MnO2-N was the smallest among those inherent to α-/β-/γ-MnO2 and α-/γ-MnO2-N. Hence, α-MnO2-N prompted the rate-determining stage of the •OH → NO3 • route (•OH desorption) in the most efficient manner, as also evidenced by the analysis on the energy barrier required to proceed with the •OH → NO3 • route. Meanwhile, XANES and in situ DRIFT spectroscopy experiments corroborated that α-MnO2-N provided a larger concentration of surface NO3 - species with bi-dentate binding arrays than γ-MnO2-N. Hence, α-MnO2-N could outperform γ-MnO2-N in improving the collision frequency between •OH and NO3 - species and in facilitating the exothermic transition of NO3 - functionalities to surface NO3 • analogues per unit time. These were corroborated by a greater efficiency of α-MnO2-N in decomposing phenol, in addition to scavenging/filtration control runs and DFT calculations. Importantly, supported NO3 • species provided 5-7-fold greater efficiency in degrading textile wastewater than conventional •OH and supported SO4 •- analogues we discovered previously.
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Affiliation(s)
- Jongsik Kim
- Extreme
Materials Research Center, Korea Institute
of Science and Technology, Seoul 02792, South
Korea
| | - Yun Jeong Choe
- Extreme
Materials Research Center, Korea Institute
of Science and Technology, Seoul 02792, South
Korea
- Department
of Materials Science and Engineering, Seoul
National University, Seoul 08826, South Korea
| | - Sang Hoon Kim
- Extreme
Materials Research Center, Korea Institute
of Science and Technology, Seoul 02792, South
Korea
- Division
of Nano and Information Technology, Korea Institute of Science and
Technology School, University of Science
and Technology, Daejeon 34113, South Korea
| | - In-Suk Choi
- Department
of Materials Science and Engineering, Seoul
National University, Seoul 08826, South Korea
| | - Keunhong Jeong
- Department
of Chemistry, Korea Military Academy, Seoul 01805, South Korea
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Huang Y, Jia Y, Hou R, Huang Z, Shen K, Jin G, Hou L. Photocatalytic degradation of unsymmetrical dimethylhydrazine on TiO 2/SBA-15 under 185/254 nm vacuum-ultraviolet. RSC Adv 2021; 11:24172-24182. [PMID: 35479060 PMCID: PMC9036703 DOI: 10.1039/d1ra03599a] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Accepted: 07/01/2021] [Indexed: 11/21/2022] Open
Abstract
In this work, TiO2/SBA-15 was synthesized via an in situ hydrothermal method and was used for vacuum-ultraviolet (VUV) photocatalytic degradation of unsymmetrical dimethylhydrazine (UDMH) for the first time. Compared with photocatalysis under UV irradiation, VUV photocatalysis exhibited higher photodegradation efficiency due to the synergetic effect of direct photolysis, indirect photooxidation and photocatalytic oxidation. The synthesized TiO2/SBA-15 catalysts exhibited ordered mesoporous structure and anatase phase TiO2. Titanium content, initial pH and substrate concentration impacted degradation efficiency of UDMH in the VUV photocatalysis process. Among the prepared catalysts, TiO2/SBA-15 with the molar ratio of Ti/Si = 1 : 3 (TS-2) showed the best photocatalytic activity under VUV light, with the rate constant of 0.02511 min−1, which is 1.91 times that with VUV/P25. The superior photocatalytic activity of TS-2 is mainly related to the good balance between the specific surface area and TiO2 contents. The photodegradation efficiency decreases with the increase in the initial UDMH concentration and the maximum degradation rate was obtained at pH 9.0. In the VUV/TS-2 process, ˙OH played a more important role in the degradation of UDMH than ˙O2− and the degradation pathways contained bond breaking, amidation, isomerisation and oxidation reactions. The TS-2 also showed good reusability with the rate constant maintained at above 90% after five cycles and exhibited satisfactory degradation efficiency in tap water. Mesoporous TiO2/SBA-15 under VUV irradiation: enhanced photocatalytic oxidation for UDMH degradation.![]()
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Affiliation(s)
| | - Ying Jia
- Xi'an High Technology Institute Xi'an 710025 China
| | - Ruomeng Hou
- Xi'an High Technology Institute Xi'an 710025 China
| | | | - Keke Shen
- Xi'an High Technology Institute Xi'an 710025 China
| | - Guofeng Jin
- Xi'an High Technology Institute Xi'an 710025 China
| | - Li'an Hou
- Xi'an High Technology Institute Xi'an 710025 China
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