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Yang Y, Miao C, Wang R, Zhang R, Li X, Wang J, Wang X, Yao J. Advances in morphology-controlled alumina and its supported Pd catalysts: synthesis and applications. Chem Soc Rev 2024; 53:5014-5053. [PMID: 38600823 DOI: 10.1039/d3cs00776f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2024]
Abstract
Alumina materials, as one of the cornerstones of the modern chemical industry, possess physical and chemical properties that include excellent mechanical strength and structure stability, which also make them highly suitable as catalyst supports. Alumina-supported Pd-based catalysts with the advantages of exceptional catalytic performance, flexible regulated surface metal/acid sites, and good regeneration ability have been widely used in many traditional chemical industry fields and have also shown great application prospects in emerging fields. This review aims to provide an overview of the recent advances in alumina and its supported Pd-based catalysts. Specifically, the synthesis strategies, morphology transformation mechanisms, and structural properties of alumina with various morphologies are comprehensively summarized and discussed in-depth. Then, the preparation approaches of Pd/Al2O3 catalysts (impregnation, precipitation, and other emerging methods), as well as the metal-support interactions (MSIs), are revisited. Moreover, Some promising applications have been chosen as representative reactions in fine chemicals, environmental purification, and sustainable development fields to highlight the universal functionality of the alumina-supported Pd-based catalysts. The role of the Pd species, alumina support, promoters, and metal-support interactions in the enhancement of catalytic performance are also discussed. Finally, some challenges and upcoming opportunities in the academic and industrial application of the alumina and its supported Pd-based are presented and put forward.
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Affiliation(s)
- Yanpeng Yang
- SINOPEC Research Institute of Petroleum Processing Co., Ltd., Beijing, 100083, P. R. China.
| | - Chenglin Miao
- SINOPEC Research Institute of Petroleum Processing Co., Ltd., Beijing, 100083, P. R. China.
| | - Ruoyu Wang
- SINOPEC Research Institute of Petroleum Processing Co., Ltd., Beijing, 100083, P. R. China.
| | - Rongxin Zhang
- SINOPEC Research Institute of Petroleum Processing Co., Ltd., Beijing, 100083, P. R. China.
| | - Xiaoyu Li
- SINOPEC Research Institute of Petroleum Processing Co., Ltd., Beijing, 100083, P. R. China.
| | - Jieguang Wang
- SINOPEC Research Institute of Petroleum Processing Co., Ltd., Beijing, 100083, P. R. China.
| | - Xi Wang
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, School of Physical Science and Engineering, Beijing Jiaotong University, Beijing 100044, P. R. China.
- Chemistry and Chemical Engineering Guangdong Laboratory, Shantou, 51031, P. R. China
| | - Jiannian Yao
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Science, Beijing 100190, P. R. China.
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2
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Lim J, Cullen DA, Stavitski E, Lee SW, Hatzell MC. Atomically Ordered PdCu Electrocatalysts for Selective and Stable Electrochemical Nitrate Reduction. ACS ENERGY LETTERS 2023; 8:4746-4752. [PMID: 37969250 PMCID: PMC10644382 DOI: 10.1021/acsenergylett.3c01672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Accepted: 09/12/2023] [Indexed: 11/17/2023]
Abstract
Electrochemical nitrate reduction (NO3 RR) has attracted attention as an emerging approach to mitigate nitrate pollution in groundwater. Here, we report that a highly ordered PdCu alloy-based electrocatalyst exhibits selective (91% N2), stable (480 h), and near complete (94%) removal of nitrate without loss of catalyst. In situ and ex situ XAS provide evidence that structural ordering between Pd and Cu improves long-term catalyst stability during NO3RR. In contrast, we also report that a disordered PdCu alloy-based electrocatalyst exhibits non-selective (44% N2 and 49% NH4+), unstable, and incomplete removal of nitrate. The copper within disordered PdCu alloy is vulnerable to accepting electrons from hydrogenated neighboring Pd atoms. This resulted in copper catalyst losses which were 10× greater than that of the ordered catalyst. The design of stable catalysts is imperative for water treatment because loss of the catalyst adds to the system cost and environmental impacts.
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Affiliation(s)
- Jeonghoon Lim
- George
W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - David A. Cullen
- Center
for Nanophase Materials Sciences, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Eli Stavitski
- National
Synchrotron Light Source II, Brookhaven
National Laboratory, Upton, New York 11973, United States
| | - Seung Woo Lee
- George
W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Marta C. Hatzell
- George
W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
- School
of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 United States
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3
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Zhao Z, Wu Y, Ran W, Zhao H, Yu X, Sun JF, He G, Liu J, Liu R, Jiang G. AuFe 3@Pd/γ-Fe 2O 3 Nanosheets as an In Situ Regenerable and Highly Efficient Hydrogenation Catalyst. ACS NANO 2023; 17:8499-8510. [PMID: 37074122 DOI: 10.1021/acsnano.3c00745] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Heterogenous Pd catalysts play a pivotal role in the chemical industry; however, it is plagued by S2- or other strong adsorbates inducing surface poisoning long term. Herein, we report the development of AuFe3@Pd/γ-Fe2O3 nanosheets (NSs) as an in situ regenerable and highly active hydrogenation catalyst. Upon poisoning, the Pd monolayer sites could be fully and oxidatively regenerated under ambient conditions, which is initiated by •OH radicals from surface defect/FeTetra vacancy-rich γ-Fe2O3 NSs via the Fenton-like pathway. Both experimental and theoretical analyses demonstrate that for the electronic and geometric effect, the 2-3 nm AuFe3 intermetallic nanocluster core promotes the adsorption of reactant onto Pd sites; in addition, it lowers Pd's affinity for •OH radicals to enhance their stability during oxidative regeneration. When packed into a quartz sand fixed-bed catalyst column, the AuFe3@Pd/γ-Fe2O3 NSs are highly active in hydrogenating the carbon-halogen bond, which comprises a crucial step for the removal of micropollutants in drinking water and recovery of resources from heavily polluted wastewater, and withstand ten rounds of regeneration. By maximizing the use of ultrathin metal oxide NSs and intermetallic nanocluster and monolayer Pd, the current study demonstrates a comprehensive strategy for developing sustainable Pd catalysts for liquid catalysis.
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Affiliation(s)
- Zongshan Zhao
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences Chinese Academy of Sciences, Beijing 100085, China
- School of Environmental Science and Engineering, Qingdao University, Qingdao 266071, China
| | - Yanhen Wu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences Chinese Academy of Sciences, Beijing 100085, China
- School of Environmental Science and Engineering, Qingdao University, Qingdao 266071, China
| | - Wei Ran
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences Chinese Academy of Sciences, Beijing 100085, China
- School of Environment, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China
| | - Huachao Zhao
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences Chinese Academy of Sciences, Beijing 100085, China
| | - Xiaotian Yu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences Chinese Academy of Sciences, Beijing 100085, China
| | - Jie-Fang Sun
- Beijing Center for Disease Prevention and Control, Beijing 100013, China
| | - Guangzhi He
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences Chinese Academy of Sciences, Beijing 100085, China
| | - Jingfu Liu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences Chinese Academy of Sciences, Beijing 100085, China
- School of Environmental Science and Engineering, Qingdao University, Qingdao 266071, China
- School of Environment, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China
| | - Rui Liu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences Chinese Academy of Sciences, Beijing 100085, China
- School of Environmental Science and Engineering, Qingdao University, Qingdao 266071, China
- School of Environment, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China
| | - Guibin Jiang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences Chinese Academy of Sciences, Beijing 100085, China
- School of Environmental Science and Engineering, Qingdao University, Qingdao 266071, China
- School of Environment, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China
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4
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Mallick SP, Mallick Z, Mayer BK. Meta-analysis of the prevalence of dissolved organic nitrogen (DON) in water and wastewater and review of DON removal and recovery strategies. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 828:154476. [PMID: 35276173 DOI: 10.1016/j.scitotenv.2022.154476] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 02/26/2022] [Accepted: 03/07/2022] [Indexed: 06/14/2023]
Abstract
Most wastewater removal and recovery processes primarily target dissolved inorganic nitrogen (DIN) species, leaving the untreated non-reactive dissolved organic nitrogen (DON) in the effluent. This DON fraction can account for a substantial part of the total nitrogen (N) load. We analyzed large datasets of N species and concentrations (with a focus on quantifying the fraction of DON) in surface water, ground water, and wastewater effluent across the United States. We then reviewed strategies to remove and recover DON based on results of a range of treatment technologies reported in the literature, including laboratory-scale up to full-scale operation in wastewater treatment plants. Our meta-analysis showed that DON concentrations are greatest in wastewater effluent followed by surface water and groundwater. The concentration of DON in wastewater effluent varied from 0.01 to 10.9 mg N/L (number of data points, n = 163), where the range in surface water was 0.002 to 14.3 mg N/L (n = 11,803). Organic N accounted for the majority of total N in 12.3% of wastewater effluent samples and 49.1% of surface waters. Our literature review showed that currently available wastewater treatment processes do not efficiently target DON removal nor recovery of the DON as a valuable product. One potential DON removal and recovery strategy is transforming DON into DIN, which is generally more easily removed and recovered. Transformation strategies reported in the literature include ozonation, UV/H2O2, and electrooxidation. However, as advanced oxidation processes are often energy- and cost-intensive, further research is needed to improve DON removal and recovery.
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Affiliation(s)
- Synthia P Mallick
- Department of Civil, Construction and Environmental Engineering, Marquette University, 1637 West Wisconsin Avenue, Milwaukee, WI 53233, USA.
| | - Zayed Mallick
- Department of Environmental Science & Management, North South University, Bashundhara, Dhaka 1229, Bangladesh.
| | - Brooke K Mayer
- Department of Civil, Construction and Environmental Engineering, Marquette University, 1637 West Wisconsin Avenue, Milwaukee, WI 53233, USA.
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5
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Sanchis I, Diaz E, Pizarro A, Rodriguez J, Mohedano A. Nitrate reduction with bimetallic catalysts. A stability-addressed overview. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.120750] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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6
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Engineering of Nanostructured Carbon Catalyst Supports for the Continuous Reduction of Bromate in Drinking Water. Mol Vis 2022. [DOI: 10.3390/c8020021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Recent works in the development of nanostructured catalysts for bromate reduction in drinking water under hydrogen have highlighted the importance of the properties of the metallic phase support in their overall performance. Since most works in catalyst development are carried out in powder form, there is an overlooked gap in the correlation between catalyst support properties and performance in typical continuous applications such as fixed bed reactors. In this work, it is shown that the mechanical modification of commercially available carbon nanotubes, one of the most promising supports, can significantly enhance the activity of the catalytic system when tested in a stirred tank reactor, but upon transition to a fixed bed reactor, the formation of preferential pathways for the liquid flow and high pressure drops were observed. This effect could be minimized by the addition of an inert filler to increase the bed porosity; however, the improvement in catalytic performance when compared with the as-received support material was not retained. The operation of the continuous catalytic system was then optimized using a 1 wt.% Pd catalyst supported on the as-received carbon nanotubes. Effluent and hydrogen flow rates as well as catalyst loadings were systematically optimized to find an efficient set of parameters for the operation of the system, regarding its catalytic performance, capacity to treat large effluent flows, and minimization of catalyst and hydrogen requirements. Experiments carried out in the presence of distilled water as a reaction medium demonstrate that bromate can be efficiently removed from the liquid phase, whereas when using a real water matrix, a tendency for the deactivation of the catalyst over time was more apparent throughout 200 flow passages over the catalytic bed, which was mostly attributed to the competitive adsorption of inorganic matter on the catalyst active centers, or the formation of mineral deposits blocking access to the catalyst.
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7
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Lee CS, Guo S, Rho H, Levi J, Garcia-Segura S, Wong MS, Gardea-Torresdey J, Westerhoff P. Unified Metallic Catalyst Aging Strategy and Implications for Water Treatment. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:10.1021/acs.est.1c02364. [PMID: 34309365 PMCID: PMC9720895 DOI: 10.1021/acs.est.1c02364] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Heterogeneous catalysis holds great promise for oxidizing or reducing a range of pollutants in water. A well-recognized, but understudied, barrier to implement catalytic treatment centers around fouling or aging over time of the catalyst surfaces. To better understand how to study catalyst fouling or aging, we selected a representative bimetallic catalyst (Pd-In supported on Al2O3), which holds promise to reduce nitrate to innocuous nitrogen gas byproducts upon hydrogen addition, and six model solutions (deionized water, sodium hypochlorite, sodium borohydride, acetic acid, sodium sulfide, and tap water). Our novel aging experimental apparatus permitted single passage of each model solution, separately, through a small packed-bed reactor containing replicate bimetallic catalyst "beds" that could be sacrificed weekly for off-line characterization to quantify impacts of fouling or aging. The composition of the model solutions led to the following gradual changes in surface composition, morphology, or catalytic reactivity: (i) formation of passivating species, (ii) decreased catalytic sites due to metal leaching under acid conditions or sulfide poisoning, (iii) dissolution and/or transformation of indium, (iv) formation of new catalytic sites by the introduction of an additional metallic element, and (v) oxidative etching. The model solution water chemistry captured a wide range of conditions likely to be encountered in potable or industrial water treatment. Aging-induced changes altered catalytic activity and provided insights into potential strategies to improve long-term catalyst operations for water treatment.
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Affiliation(s)
- Chung-Seop Lee
- School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ 85287-3005, USA
| | - Sujin Guo
- Department of Civil and Environmental Engineering, Rice University, 6100 S. Main Street, Houston, TX 77005, USA
| | - Hojung Rho
- School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ 85287-3005, USA
| | - Juliana Levi
- School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ 85287-3005, USA
| | - Sergi Garcia-Segura
- School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ 85287-3005, USA
| | - Michael S. Wong
- Department of Civil and Environmental Engineering, Rice University, 6100 S. Main Street, Houston, TX 77005, USA
| | - Jorge Gardea-Torresdey
- Department of Chemistry and Biochemistry, The University of Texas at El Paso, El Paso, TX, 79968, USA
| | - Paul Westerhoff
- School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ 85287-3005, USA
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8
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Metallic nanoparticles for electrocatalytic reduction of halogenated organic compounds: A review. Electrochim Acta 2021. [DOI: 10.1016/j.electacta.2021.138039] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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9
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Jia Y, Qian D, Chen Y, Hu Y. Intra/extracellular electron transfer for aerobic denitrification mediated by in-situ biosynthesis palladium nanoparticles. WATER RESEARCH 2021; 189:116612. [PMID: 33189971 DOI: 10.1016/j.watres.2020.116612] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 10/31/2020] [Accepted: 11/05/2020] [Indexed: 06/11/2023]
Abstract
The slow electron transfer rate is the bottleneck to the biological wastewater treatment process, and the nanoparticles (NPs) has been verified as a feasible strategy to improve the biological degradation efficiency by accelerating the electron transfer. Here, we employed the Gram-positive Bacillus megaterium Y-4, capable of synthetizing Pd(0), to investigate the intra/extracellular electron transfer (IET/EET) mechanisms mediated by NPs in aerobic denitrification for the first time. Kinetic and thermodynamic results showed that the bio-Pd(0) could significantly promote the removal of both nitrate and nitrite by improving affinity and decreasing activation energy. The enzymic activity and the respiration chain inhibition experiment indicated that the bio-Pd(0) could facilitate the nitrate biotic reduction by improving the Fe-S center activity and serving as parallel H carriers to replace coenzyme Q to selectively increase the electron flux toward nitrate in IET, while promoting the nitrite reduction by abiotic catalysis. Most importantly, the detection of DPV peak at -226~-287 mV proved that the one-electron EET via multiheme cytochrome-bound flavins also occurred in Gram-positive bacteria and enhanced in Pd-loaded cells. In addition, the remarkable increase of the formal charge in EPS indicated that the bio-Pd(0) could act as an electron shuttle to increase the redox site in EPS, eventually accelerating the electron hopping in long-distance electron transfer. Overall, this study expanded our understanding of the roles of bio-Pd(0) on the aerobic denitrification process and provided an insight into the IET/EET of Gram-positive strains.
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Affiliation(s)
- Yating Jia
- Ministry of Education Key Laboratory of Pollution Control and Ecological Remediation for Industrial Agglomeration Area, School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China
| | - Danshi Qian
- Ministry of Education Key Laboratory of Pollution Control and Ecological Remediation for Industrial Agglomeration Area, School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China
| | - Yuancai Chen
- Ministry of Education Key Laboratory of Pollution Control and Ecological Remediation for Industrial Agglomeration Area, School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China.
| | - Yongyou Hu
- Ministry of Education Key Laboratory of Pollution Control and Ecological Remediation for Industrial Agglomeration Area, School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China
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10
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Lin Y, Cao Y, Yao Q, Chai OJH, Xie J. Engineering Noble Metal Nanomaterials for Pollutant Decomposition. Ind Eng Chem Res 2020. [DOI: 10.1021/acs.iecr.0c04258] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Yingzheng Lin
- Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, Fuzhou 350207, P. R. China
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117585, Singapore
| | - Yitao Cao
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117585, Singapore
| | - Qiaofeng Yao
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117585, Singapore
| | - Osburg Jin Huang Chai
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117585, Singapore
| | - Jianping Xie
- Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, Fuzhou 350207, P. R. China
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117585, Singapore
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11
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Nieto-Sandoval J, Ortiz D, Munoz M, de Pedro ZM, Casas JA. On the deactivation and regeneration of Pd/Al2O3 catalyst for aqueous-phase hydrodechlorination of diluted chlorpromazine solution. Catal Today 2020. [DOI: 10.1016/j.cattod.2019.06.028] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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12
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Marchesini FA, Mendow G, Picard NP, Zoppas FM, Aghemo VS, Gutierrez LB, Querini CA, Miró EE. PdIn Catalysts in a Continuous Fixed Bed Reactor for the Nitrate Removal from Groundwater. INTERNATIONAL JOURNAL OF CHEMICAL REACTOR ENGINEERING 2019. [DOI: 10.1515/ijcre-2018-0126] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
The ground water (GW) is a real sample of water which contains nitrates (81 mg/L), carbonates and sulphates. This sample was treated by catalytic reduction in a bubble column fixed-bed reactor. The reaction conditions were room temperature and atmospheric pressure, and hydrogen was used as reducing agent. A comparison between the catalytic activity of Pd,In/SiO2 and Pd,In/Al2O3 catalysts was performed, giving the latter the best results regarding the nitrate conversion and the former the selectivity to nitrogen. Synthetic water containing nitrates (SW) and the groundwater (GW) with high salinity (81 mg/L nitrates) and humic acid content were treated in these conditions using HCl and CO2 as acidifiers. When the SW was acidified with CO2 at an H2 flow (2.17 mL/min), more than 50 % of conversion was obtained with an ammonia and nitrite concentrations of 0.44 and 0.92 ppm respectively. These results reached the level established by the WHO and the USEPA. However, both Pd,In/SiO2 and Pd,In/Al2O3 catalysts showed evidence of some deactivation process. This deactivation was higher in the GW sample, possibly due to the presence of Ca+2 and Mg+2 cations that precipitate on the active sites, and/or the presence of humic acids. The characterization studies indicated that, after the reaction, the composition of the metal phases was modified, specifically on their surface. As the catalyst activity is related to surface ratio Pd/In, a relative increase in the concentration of Pd decreases the activity and causes changes in the selectivity to N2. Some sintering of the metal particles was also observed to contribute to catalyst deactivation. Nevertheless, promising results were obtained since a high water volume could be treated with a relatively low amount of low metal loading catalysts.
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13
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Almassi S, Li Z, Xu W, Pu C, Zeng T, Chaplin BP. Simultaneous Adsorption and Electrochemical Reduction of N-Nitrosodimethylamine Using Carbon-Ti 4O 7 Composite Reactive Electrochemical Membranes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:928-937. [PMID: 30547581 DOI: 10.1021/acs.est.8b05933] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
This study focused on synthesis and characterization of Ti4O7 reactive electrochemical membranes (REMs) amended with powder-activated carbon (PAC) or multiwalled carbon nanotubes (MWCNTs). These composite REMs were evaluated for simultaneous adsorption and electrochemical reduction of N-nitrosodimethylamine (NDMA). The carbon-Ti4O7 composite REMs had high electrical conductivities (1832 to 2991 S m-1), where carbon and Ti4O7 were in direct electrical contact. Addition of carbonaceous materials increased the residence times of NDMA in the REMs by a factor of 3.8 to 5.4 and therefore allowed for significant electrochemical NDMA reduction. The treatment of synthetic solutions containing 10 μM NDMA achieved >4-log NDMA removal in a single pass (liquid residence time of 11 to 22 s) through the PAC-REM and MWCNT-REM with the application of a -1.1 V/SHE cathodic potential, with permeate concentrations between 18 and 80 ng L-1. The treatment of a 6.7 nM NDMA-spiked surface water sample, under similar operating conditions (liquid residence time of 22 s), achieved 92 to 97% removal with permeate concentrations between 16 and 40 ng L-1. Density functional theory calculations determined a probable reaction mechanism for NDMA reduction, where the rate-limiting step was a direct electron transfer reaction.
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Affiliation(s)
- Soroush Almassi
- Department of Chemical Engineering , University of Illinois at Chicago , 810 S. Clinton Street , Chicago , Illinois 60607 , United States
| | - Zhao Li
- Department of Civil and Environmental Engineering , Villanova University , 800 E. Lancaster Avenue , Villanova , Pennsylvania 19085 , United States
| | - Wenqing Xu
- Department of Civil and Environmental Engineering , Villanova University , 800 E. Lancaster Avenue , Villanova , Pennsylvania 19085 , United States
| | - Changcheng Pu
- Department of Civil and Environmental Engineering , Syracuse University , 151 Link Hall , Syracuse , New York 13244 , United States
| | - Teng Zeng
- Department of Civil and Environmental Engineering , Syracuse University , 151 Link Hall , Syracuse , New York 13244 , United States
| | - Brian P Chaplin
- Department of Chemical Engineering , University of Illinois at Chicago , 810 S. Clinton Street , Chicago , Illinois 60607 , United States
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14
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Guo S, Heck K, Kasiraju S, Qian H, Zhao Z, Grabow LC, Miller JT, Wong MS. Insights into Nitrate Reduction over Indium-Decorated Palladium Nanoparticle Catalysts. ACS Catal 2017. [DOI: 10.1021/acscatal.7b01371] [Citation(s) in RCA: 127] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | | | - Sashank Kasiraju
- Department
of Chemical and Biomolecular Engineering, University of Houston, 4726 Calhoun Road, Houston, Texas 77204-4004, United States
| | | | | | - Lars C. Grabow
- Department
of Chemical and Biomolecular Engineering, University of Houston, 4726 Calhoun Road, Houston, Texas 77204-4004, United States
| | - Jeffrey T. Miller
- Department
of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
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15
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Comandella D, Ahn MH, Kim H, Mackenzie K. Enhanced protection of PDMS-embedded palladium catalysts by co-embedding of sulphide-scavengers. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 601-602:658-668. [PMID: 28577401 DOI: 10.1016/j.scitotenv.2017.05.154] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 05/10/2017] [Accepted: 05/17/2017] [Indexed: 06/07/2023]
Abstract
For Pd-containing hydrodechlorination catalysts, coating with poly(dimethyl siloxane) (PDMS) was proposed earlier as promising protection scheme against poisoning. The PDMS coating can effectively repel non-permeating poisons (such as SO32-) retaining the hydrodechlorination Pd activity. In the present study, the previously achieved protection efficiency was enhanced by incorporation of sulphide scavengers into the polymer. The embedded scavengers were able to bind permeating non-ionic poisons (such as H2S) during their passage through PDMS prior to Pd contact which ensured an extended catalyst lifetime. Three scavenger types forming non-permeable sulphur species from H2S - alkaline, oxidative or iron-based compounds - were either incorporated into single-layer coats around individual Pd/Al2O3 particles or into a second layer above Pd-containing PDMS films (Pd-PDMS). Hydrodechlorination and hydrogenation were chosen as model reactions, carried out in batch and continuous-flow reactors. Batch tests with all scavenger-containing catalysts showed extended Pd protection compared to scavenger-free catalysts. Solid alkaline compounds (Ca(OH)2, NaOH, CaO) and MnO2 showed the highest instantaneous scavenger efficiencies (retained Pd activity=30-60%), while iron-based catalysts, such as nano zero-valent iron (nZVI) or ferrocene (FeCp2), proved less efficient (1-10%). When stepwise poisoning was applied, the protection efficiency of iron-based and oxidizing compounds was higher in the long term than that of alkaline solids. Long-term experiments in mixed-flow reactors were performed with selected scavengers, revealing the following trend of protection efficiency: CaO2>Ca(OH)2>FeCp2. Under field-simulating conditions using a fixed-bed reactor, the combination of sulphide pre-oxidation in the water phase by H2O2 and local scavenger-enhanced Pd protection was successful. The oxidizing agent H2O2 does not disturb the Pd-catalysed reduction, while the PDMS-incorporated scavenger considerably extends the catalyst life in the presence of H2S. This work demonstrates that the scavenger-based protection strategy is an effective means to increase the resistance of PDMS-embedded Pd against permeating poisons.
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Affiliation(s)
- Daniele Comandella
- Helmholtz Centre for Environmental Research - UFZ, Department of Environmental Engineering, Leipzig, Germany
| | - Min Hyung Ahn
- Helmholtz Centre for Environmental Research - UFZ, Department of Environmental Engineering, Leipzig, Germany
| | - Hojeong Kim
- Division of Water Environment, Korea Environmental Institute (KEI), Sejong, Republic of Korea
| | - Katrin Mackenzie
- Helmholtz Centre for Environmental Research - UFZ, Department of Environmental Engineering, Leipzig, Germany.
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16
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Seraj S, Kunal P, Li H, Henkelman G, Humphrey SM, Werth CJ. PdAu Alloy Nanoparticle Catalysts: Effective Candidates for Nitrite Reduction in Water. ACS Catal 2017. [DOI: 10.1021/acscatal.6b03647] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sarah Seraj
- Department
of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, 301 East Dean Keeton Street, Stop C1700, Austin, Texas 78712, United States
| | - Pranaw Kunal
- Department
of Chemistry, The University of Texas at Austin, 100 East 24th Street, Stop A1590, Austin, Texas 78712, United States
| | - Hao Li
- Department
of Chemistry, The University of Texas at Austin, 100 East 24th Street, Stop A1590, Austin, Texas 78712, United States
| | - Graeme Henkelman
- Department
of Chemistry, The University of Texas at Austin, 100 East 24th Street, Stop A1590, Austin, Texas 78712, United States
| | - Simon M. Humphrey
- Department
of Chemistry, The University of Texas at Austin, 100 East 24th Street, Stop A1590, Austin, Texas 78712, United States
| | - Charles J. Werth
- Department
of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, 301 East Dean Keeton Street, Stop C1700, Austin, Texas 78712, United States
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17
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Zheng Q, Durkin DP, Elenewski JE, Sun Y, Banek NA, Hua L, Chen H, Wagner MJ, Zhang W, Shuai D. Visible-Light-Responsive Graphitic Carbon Nitride: Rational Design and Photocatalytic Applications for Water Treatment. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:12938-12948. [PMID: 27934277 DOI: 10.1021/acs.est.6b02579] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Graphitic carbon nitride (g-C3N4) has recently emerged as a promising visible-light-responsive polymeric photocatalyst; however, a molecular-level understanding of material properties and its application for water purification were underexplored. In this study, we rationally designed nonmetal doped, supramolecule-based g-C3N4 with improved surface area and charge separation. Density functional theory (DFT) simulations indicated that carbon-doped g-C3N4 showed a thermodynamically stable structure, promoted charge separation, and had suitable energy levels of conduction and valence bands for photocatalytic oxidation compared to phosphorus-doped g-C3N4. The optimized carbon-doped, supramolecule-based g-C3N4 showed a reaction rate enhancement of 2.3-10.5-fold for the degradation of phenol and persistent organic micropollutants compared to that of conventional, melamine-based g-C3N4 in a model buffer system under the irradiation of simulated visible sunlight. Carbon-doping but not phosphorus-doping improved reactivity for contaminant degradation in agreement with DFT simulation results. Selective contaminant degradation was observed on g-C3N4, likely due to differences in reactive oxygen species production and/or contaminant-photocatalyst interfacial interactions on different g-C3N4 samples. Moreover, g-C3N4 is a robust photocatalyst for contaminant degradation in raw natural water and (partially) treated water and wastewater. In summary, DFT simulations are a viable tool to predict photocatalyst properties and oxidation performance for contaminant removal, and they guide the rational design, fabrication, and implementation of visible-light-responsive g-C3N4 for efficient, robust, and sustainable water treatment.
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Affiliation(s)
- Qinmin Zheng
- Department of Civil and Environmental Engineering, The George Washington University , Washington, DC 20052, United States
| | - David P Durkin
- Department of Chemistry, Johns Hopkins University , Baltimore, Maryland 21218, United States
| | - Justin E Elenewski
- Department of Chemistry, The George Washington University , Washington, DC 20052, United States
| | - Yingxue Sun
- Department of Civil and Environmental Engineering, The George Washington University , Washington, DC 20052, United States
- Department of Environmental Science and Engineering, Beijing Technology and Business University , Beijing 100048, China
| | - Nathan A Banek
- Department of Chemistry, The George Washington University , Washington, DC 20052, United States
| | - Likun Hua
- Department of Civil and Environmental Engineering, New Jersey Institute of Technology , Newark, New Jersey 07102, United States
| | - Hanning Chen
- Department of Chemistry, The George Washington University , Washington, DC 20052, United States
| | - Michael J Wagner
- Department of Chemistry, The George Washington University , Washington, DC 20052, United States
| | - Wen Zhang
- Department of Civil and Environmental Engineering, New Jersey Institute of Technology , Newark, New Jersey 07102, United States
| | - Danmeng Shuai
- Department of Civil and Environmental Engineering, The George Washington University , Washington, DC 20052, United States
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18
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Bergquist AM, Choe JK, Strathmann TJ, Werth CJ. Evaluation of a hybrid ion exchange-catalyst treatment technology for nitrate removal from drinking water. WATER RESEARCH 2016; 96:177-87. [PMID: 27043747 DOI: 10.1016/j.watres.2016.03.054] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 03/22/2016] [Accepted: 03/23/2016] [Indexed: 05/06/2023]
Abstract
Ion exchange (IX) is the most common approach to treating nitrate-contaminated drinking water sources, but the cost of salt to make regeneration brine, as well as the cost and environmental burden of waste brine disposal, are major disadvantages. A hybrid ion exchange-catalyst treatment system, in which waste brine is catalytically treated for reuse, shows promise for reducing costs and environmental burdens of the conventional IX system. An IX model with separate treatment and regeneration cycles was developed, and ion selectivity coefficients for each cycle were separately calibrated by fitting experimental data. Of note, selectivity coefficients for the regeneration cycle required fitting the second treatment cycle after incomplete resin regeneration. The calibrated and validated model was used to simulate many cycles of treatment and regeneration using the hybrid system. Simulated waste brines and a real brine obtained from a California utility were also evaluated for catalytic nitrate treatment in a packed-bed, flow-through column with 0.5 wt%Pd-0.05 wt%In/activated carbon support (PdIn/AC). Consistent nitrate removal and no apparent catalyst deactivation were observed over 23 d (synthetic brine) and 45 d (real waste brine) of continuous-flow treatment. Ion exchange and catalyst results were used to evaluate treatment of 1 billion gallons of nitrate-contaminated source water at a 0.5 MGD water treatment plant. Switching from a conventional IX system with a two bed volume regeneration to a hybrid system with the same regeneration length and sequencing batch catalytic reactor treatment would save 76% in salt cost. The results suggest the hybrid system has the potential to address the disadvantages of a conventional IX treatment systems.
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Affiliation(s)
- Allison M Bergquist
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Jong Kwon Choe
- Department of Civil and Environmental Engineering, Clarkson University, Potsdam, NY 13699, USA
| | - Timothy J Strathmann
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401, USA
| | - Charles J Werth
- Department of Civil, Architectural, and Environmental Engineering, University of Texas at Austin, Austin, TX 78712, USA.
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19
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Choe JK, Bergquist AM, Jeong S, Guest JS, Werth CJ, Strathmann TJ. Performance and life cycle environmental benefits of recycling spent ion exchange brines by catalytic treatment of nitrate. WATER RESEARCH 2015; 80:267-280. [PMID: 26005787 DOI: 10.1016/j.watres.2015.05.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 04/22/2015] [Accepted: 05/01/2015] [Indexed: 06/04/2023]
Abstract
Salt used to make brines for regeneration of ion exchange (IX) resins is the dominant economic and environmental liability of IX treatment systems for nitrate-contaminated drinking water sources. To reduce salt usage, the applicability and environmental benefits of using a catalytic reduction technology to treat nitrate in spent IX brines and enable their reuse for IX resin regeneration were evaluated. Hybrid IX/catalyst systems were designed and life cycle assessment of process consumables are used to set performance targets for the catalyst reactor. Nitrate reduction was measured in a typical spent brine (i.e., 5000 mg/L NO3(-) and 70,000 mg/L NaCl) using bimetallic Pd-In hydrogenation catalysts with variable Pd (0.2-2.5 wt%) and In (0.0125-0.25 wt%) loadings on pelletized activated carbon support (Pd-In/C). The highest activity of 50 mgNO3(-)/(min - g(Pd)) was obtained with a 0.5 wt%Pd-0.1 wt%In/C catalyst. Catalyst longevity was demonstrated by observing no decrease in catalyst activity over more than 60 days in a packed-bed reactor. Based on catalyst activity measured in batch and packed-bed reactors, environmental impacts of hybrid IX/catalyst systems were evaluated for both sequencing-batch and continuous-flow packed-bed reactor designs and environmental impacts of the sequencing-batch hybrid system were found to be 38-81% of those of conventional IX. Major environmental impact contributors other than salt consumption include Pd metal, hydrogen (electron donor), and carbon dioxide (pH buffer). Sensitivity of environmental impacts of the sequencing-batch hybrid reactor system to sulfate and bicarbonate anions indicate the hybrid system is more sustainable than conventional IX when influent water contains <80 mg/L sulfate (at any bicarbonate level up to 100 mg/L) or <20 mg/L bicarbonate (at any sulfate level up to 100 mg/L) assuming 15 brine reuse cycles. The study showed that hybrid IX/catalyst reactor systems have potential to reduce resource consumption and improve environmental impacts associated with treating nitrate-contaminated water sources.
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Affiliation(s)
- Jong Kwon Choe
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Allison M Bergquist
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Sangjo Jeong
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Jeremy S Guest
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Charles J Werth
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Timothy J Strathmann
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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20
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Gao Z, Zhang Y, Li D, Werth CJ, Zhang Y, Zhou X. Highly active Pd-In/mesoporous alumina catalyst for nitrate reduction. JOURNAL OF HAZARDOUS MATERIALS 2015; 286:425-431. [PMID: 25600582 DOI: 10.1016/j.jhazmat.2015.01.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2014] [Revised: 12/19/2014] [Accepted: 01/02/2015] [Indexed: 06/04/2023]
Abstract
The catalytic reduction of nitrate is a promising technology for groundwater purification because it transforms nitrate into nitrogen and water. Recent studies have mainly focused on new catalysts with higher activities for the reduction of nitrate. Consequently, metal nanoparticles supported on mesoporous metal oxides have become a major research direction. However, the complex surface chemistry and porous structures of mesoporous metal oxides lead to a non-uniform distribution of metal nanoparticles, thereby resulting in a low catalytic efficiency. In this paper, a method for synthesizing the sustainable nitrate reduction catalyst Pd-In/Al2O3 with a dimensional structure is introduced. The TEM results indicated that Pd and In nanoparticles could efficiently disperse into the mesopores of the alumina. At room temperature in CO2-buffered water and under continuous H2 as the electron donor, the synthesized material (4.9 wt% Pd) was the most active at a Pd-In ratio of 4, with a first-order rate constant (k(obs) = 0.241 L min(-1) g(cata)(-1)) that was 1.3× higher than that of conventional Pd-In/Al2O3 (5 wt% Pd; 0.19 L min(-1) g(cata)(-1)). The Pd-In/mesoporous alumina is a promising catalyst for improving the catalytic reduction of nitrate.
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Affiliation(s)
- Zhenwei Gao
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China
| | - Yonggang Zhang
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China
| | - Deyi Li
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China
| | - Charles J Werth
- Civil, Architectural and Environmental Engineering, University of Texas at Austin, 301 East Dean Keeton St., Stop C1786, Austin, TX 78712, USA
| | - Yalei Zhang
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China.
| | - Xuefei Zhou
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China.
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21
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Wang Y, Liu J, Wang P, Werth CJ, Strathmann TJ. Palladium Nanoparticles Encapsulated in Core–Shell Silica: A Structured Hydrogenation Catalyst with Enhanced Activity for Reduction of Oxyanion Water Pollutants. ACS Catal 2014. [DOI: 10.1021/cs500971r] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Yin Wang
- Department
of Civil and Environmental Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Jinyong Liu
- Department
of Civil and Environmental Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Peng Wang
- Water
Desalination and Reuse Center, Biological and Environmental Sciences
and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Charles J. Werth
- Department
of Civil and Environmental Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Timothy J. Strathmann
- Department
of Civil and Environmental Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
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22
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Jung S, Bae S, Lee W. Development of Pd-Cu/hematite catalyst for selective nitrate reduction. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:9651-9658. [PMID: 25076058 DOI: 10.1021/es502263p] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A new hematite-supported Pd-Cu bimetallic catalyst (Pd-Cu/hematite) was developed in order to actively and selectively reduce nitrate (NO3(-)) to nitrogen gas (N2). Four different iron-bearing soil minerals (hematite (H), goethite (G), maghemite (M), and lepidocrocite (L)) were transformed to hematite by calcination and used for synthesis of different Pd-Cu/hematite-H, G, M, and L catalysts. Their characteristics were identified using X-ray diffraction (XRD), specific surface area (BET), temperature programed reduction (TPR), transmission electron microscopy with energy dispersive X-ray (TEM-EDX), H2 pulse chemisorption, zeta-potential, and X-ray photoelectron spectroscopy (XPS). Pd-Cu/hematite-H exhibited the highest NO3(-) removal (96.4%) after 90 min, while a lower removal (90.9, 51.1, and 30.5%) was observed in Pd-Cu/hematite-G, M, and L, respectively. The results of TEM-EDX, and TPR analysis revealed that Pd-Cu/hematite-H possessed the closest contact distance between the Cu and Pd sites on the hematite surface among the different Pd-Cu/hematite catalysts. The high removal can be also attributed to the highly active metallic sites on its positively charged surface. The XPS analysis demonstrated that the amount of hydrogen molecules can have a pivotal function on NO3(-) removal and a ratio of nitrogen to hydrogen molecule (N:H) on the Pd sites can critically determine N2 selectivity.
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Affiliation(s)
- Sungyoon Jung
- Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology , 291 Daehak-ro, Yuseong-Gu, Daejeon 305-701, Korea
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23
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Yuan S, Chen M, Mao X, Alshawabkeh AN. Effects of reduced sulfur compounds on Pd-catalytic hydrodechlorination of trichloroethylene in groundwater by cathodic H2 under electrochemically induced oxidizing conditions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:10502-9. [PMID: 23962132 PMCID: PMC3916216 DOI: 10.1021/es402169d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Reduced sulfur compounds (RSCs) poison Pd catalysts for catalytic hydrodechlorination of contaminants in anoxic groundwater. This study investigates the effects of RSCs on Pd-catalytic hydrodechlorination of trichloroethylene (TCE) in oxic groundwater. Water electrolysis in an undivided electrolytic cell is used to produce H2 for TCE hydrodechlorination under oxidizing conditions. TCE is efficiently hydrodechlorinated to ethane, with significant accumulation of H2O2 under acidic conditions. The presence of sulfide at concentrations less than 93.8 μM moderately inhibits TCE hydrodechlorination and H2O2 production. The presence of sulfite at low concentrations (≤1 mM) significantly enhances TCE decay, while at high concentration (3 mM) inhibits initially and enhances afterward when sulfite concentration declines to less than 1 mM. Using radical scavenging experiments and an electron spin resonance assay, SO3(•-), which is generated from sulfite under oxidizing conditions, is validated as the new reactive species contributing to the enhancement. This study reveals a distinct mechanism of effect of sulfite on TCE hydrodechlorination by Pd and H2 in oxic groundwater and presents an alternative approach to increasing resistance of Pd to RSCs poisoning.
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Affiliation(s)
- Songhu Yuan
- State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, P. R. China
- Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
- To whom correspondence should be addressed. (S. Yuan), (A. Alshawabkeh). Phone: 617 373 3994. Fax: 617 373 4419
| | - Mingjie Chen
- Atmospheric, Earth and Energy Division, Lawrence Livermore National Laboratory, P.O. Box 808, L8184, Livermore, CA 94550, United States
| | - Xuhui Mao
- Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Akram N. Alshawabkeh
- Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
- To whom correspondence should be addressed. (S. Yuan), (A. Alshawabkeh). Phone: 617 373 3994. Fax: 617 373 4419
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24
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Pretzer LA, Song HJ, Fang YL, Zhao Z, Guo N, Wu T, Arslan I, Miller JT, Wong MS. Hydrodechlorination catalysis of Pd-on-Au nanoparticles varies with particle size. J Catal 2013. [DOI: 10.1016/j.jcat.2012.11.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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25
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Yuan S, Chen M, Mao X, Alshawabkeh AN. A three-electrode column for Pd-catalytic oxidation of TCE in groundwater with automatic pH-regulation and resistance to reduced sulfur compound foiling. WATER RESEARCH 2013; 47:269-78. [PMID: 23121896 PMCID: PMC3581803 DOI: 10.1016/j.watres.2012.10.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2012] [Revised: 09/13/2012] [Accepted: 10/04/2012] [Indexed: 05/11/2023]
Abstract
A hybrid electrolysis and Pd-catalytic oxidation process is evaluated for degradation of trichloroethylene (TCE) in groundwater. A three-electrode, one anode and two cathodes, column is employed to automatically develop a low pH condition in the Pd vicinity and a neutral effluent. Simulated groundwater containing up to 5 mM bicarbonate can be acidified to below pH 4 in the Pd vicinity using a total of 60 mA with 20 mA passing through the third electrode. By packing 2 g of Pd/Al(2)O(3) pellets in the developed acidic region, the column efficiency for TCE oxidation in simulated groundwater (5.3 mg/L TCE) increases from 44 to 59 and 68% with increasing Fe(II) concentration from 0 to 5 and 10 mg/L, respectively. Different from Pd-catalytic hydrodechlorination under reducing conditions, this hybrid electrolysis and Pd-catalytic oxidation process is advantageous in controlling the fouling caused by reduced sulfur compounds (RSCs) because the in situ generated reactive oxidizing species, i.e., O(2), H(2)O(2) and OH, can oxidize RSCs to some extent. In particular, sulfite at concentrations less than 1 mM even greatly increases TCE oxidation by the production of SO(4)(•-), a strong oxidizing radical, and more OH.
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Affiliation(s)
- Songhu Yuan
- State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, P. R. China
- Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
- Corresponding author. (S. Yuan), (A. Alshawabkeh)
| | - Mingjie Chen
- Atmospheric, Earth and Energy Division, Lawrence Livermore National Laboratory, P.O. Box 808, L-184, Livermore, CA 94550, United States
| | - Xuhui Mao
- Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Akram N. Alshawabkeh
- Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
- Corresponding author. (S. Yuan), (A. Alshawabkeh)
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26
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Liu J, Choe JK, Sasnow Z, Werth CJ, Strathmann TJ. Application of a Re-Pd bimetallic catalyst for treatment of perchlorate in waste ion-exchange regenerant brine. WATER RESEARCH 2013; 47:91-101. [PMID: 23084116 DOI: 10.1016/j.watres.2012.09.031] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Revised: 09/09/2012] [Accepted: 09/16/2012] [Indexed: 06/01/2023]
Abstract
Concentrated sodium chloride (NaCl) brines are often used to regenerate ion-exchange (IX) resins applied to treat drinking water sources contaminated with perchlorate (ClO(4)(-)), generating large volumes of contaminated waste brine. Chemical and biological processes for ClO(4)(-) reduction are often inhibited severely by high salt levels, making it difficult to recycle waste brines. Recent work demonstrated that novel rhenium-palladium bimetallic catalysts on activated carbon support (Re-Pd/C) can efficiently reduce ClO(4)(-) to chloride (Cl(-)) under acidic conditions, and here the applicability of the process for treating waste IX brines was examined. Experiments conducted in synthetic NaCl-only brine (6-12 wt%) showed higher Re-Pd/C catalyst activity than in comparable freshwater solutions, but the rate constant for ClO(4)(-) reduction measured in a real IX waste brine was found to be 65 times lower than in the synthetic NaCl brine. Through a series of experiments, co-contamination of the IX waste brine by excess NO(3)(-) (which the catalyst reduces principally to NH(4)(+)) was found to be the primary cause for deactivation of the Re-Pd/C catalyst, most likely by altering the immobilized Re component. Pre-treatment of NO(3)(-) using a different bimetallic catalyst (In-Pd/Al(2)O(3)) improved selectivity for N(2) over NH(4)(+) and enabled facile ClO(4)(-) reduction by the Re-Pd/C catalyst. Thus, sequential catalytic treatment may be a promising strategy for enabling reuse of waste IX brine containing NO(3)(-) and ClO(4)(-).
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Affiliation(s)
- Jinyong Liu
- Department of Civil and Environmental Engineering, Center of Advanced Materials for the Purification of Water with Systems, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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27
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Zhang R, Shuai D, Guy KA, Shapley JR, Strathmann TJ, Werth CJ. Elucidation of Nitrate Reduction Mechanisms on a Pd-In Bimetallic Catalyst using Isotope Labeled Nitrogen Species. ChemCatChem 2012. [DOI: 10.1002/cctc.201200457] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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28
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Baumgartner R, McNeill K. Hydrodefluorination and hydrogenation of fluorobenzene under mild aqueous conditions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:10199-10205. [PMID: 22871102 DOI: 10.1021/es302188f] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Fluorinated organic compounds are increasingly used in many applications, and their release to the environment is expected. It is therefore important to find suitable methods for degradation of fluorinated compounds under environmentally relevant conditions. In this study, a simple heterogeneous rhodium-based catalytic system (Rh/Al(2)O(3) and H(2)) for hydrodefluorination and hydrogenation of fluorobenzene under mild aqueous conditions (1 atm of H(2), ambient temperature) was developed and the underlying reaction mechanism was investigated. Fluorobenzene degraded rapidly (t(1/2) ≈ 0.2 h) to form cyclohexane and fluoride (F(-)) as the stable end products, with benzene and cyclohexene observed as intermediates. Cyclohexadiene intermediates were not observed but were expected to form during the hydrogenation of benzene. Three postulated but unobserved fluorinated intermediates were subjected to the catalytic reaction conditions, and it was concluded that they most likely do not form during the fluorobenzene degradation reaction. Isotope labeling experiments showed that the unsaturated intermediates undergo rapid and reversible hydrogenation/dehydrogenation under the reaction conditions and also that fully saturated compounds are unreactive in the catalytic system. Both molecular hydrogen and water were sources of hydrogen in the final cyclohexane product. Kinetic fitting indicated that sorption/desorption of fluorobenzene onto the catalyst surface plays an important role in the mechanism.
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Affiliation(s)
- Rebekka Baumgartner
- Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, 8092 Zurich, Switzerland
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Hu G, Sharifi T, Nitze F, Barzegar HR, Tai CW, Wågberg T. Phase-transfer synthesis of amorphous palladium nanoparticle-functionalized 3D helical carbon nanofibers and its highly catalytic performance towards hydrazine oxidation. Chem Phys Lett 2012. [DOI: 10.1016/j.cplett.2012.05.042] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Chaplin BP, Reinhard M, Schneider WF, Schüth C, Shapley JR, Strathmann TJ, Werth CJ. Critical review of Pd-based catalytic treatment of priority contaminants in water. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:3655-3670. [PMID: 22369144 DOI: 10.1021/es204087q] [Citation(s) in RCA: 201] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Catalytic reduction of water contaminants using palladium (Pd)-based catalysts and hydrogen gas as a reductant has been extensively studied at the bench-scale, but due to technical challenges it has only been limitedly applied at the field-scale. To motivate research that can overcome these technical challenges, this review critically analyzes the published research in the area of Pd-based catalytic reduction of priority drinking water contaminants (i.e., halogenated organics, oxyanions, and nitrosamines), and identifies key research areas that should be addressed. Specifically, the review summarizes the state of knowledge related to (1) proposed reaction pathways for important classes of contaminants, (2) rates of contaminant reduction with different catalyst formulations, (3) long-term sustainability of catalyst activity with respect to natural water foulants and regeneration strategies, and (4) technology applications. Critical barriers hindering implementation of the technology are related to catalyst activity (for some contaminants), stability, fouling, and regeneration. New developments overcoming these limitations will be needed for more extensive field-scale application of this technology.
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Affiliation(s)
- Brian P Chaplin
- Department of Civil and Environmental Engineering, Villanova University, Villanova, Pennsylvania 19085, United States
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Shuai D, Choe JK, Shapley JR, Werth CJ. Enhanced activity and selectivity of carbon nanofiber supported Pd catalysts for nitrite reduction. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:2847-2855. [PMID: 22295991 DOI: 10.1021/es203200d] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Pd-based catalyst treatment represents an emerging technology that shows promise to remove nitrate and nitrite from drinking water. In this work we use vapor-grown carbon nanofiber (CNF) supports in order to explore the effects of Pd nanoparticle size and interior versus exterior loading on nitrite reduction activity and selectivity (i.e., dinitrogen over ammonia production). Results show that nitrite reduction activity increases by 3.1-fold and selectivity decreases by 8.0-fold, with decreasing Pd nanoparticle size from 1.4 to 9.6 nm. Both activity and selectivity are not significantly influenced by Pd interior versus exterior CNF loading. Consequently, turnover frequencies (TOFs) among all CNF catalysts are similar, suggesting nitrite reduction is not sensitive to Pd location on CNFs nor Pd structure. CNF-based catalysts compare favorably to conventional Pd catalysts (i.e., Pd on activated carbon or alumina) with respect to nitrite reduction activity and selectivity, and they maintain activity over multiple reduction cycles. Hence, our results suggest new insights that an optimum Pd nanoparticle size on CNFs balances faster kinetics with lower ammonia production, that catalysts can be tailored at the nanoscale to improve catalytic performance for nitrite, and that CNFs hold promise as highly effective catalyst supports in drinking water treatment.
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Affiliation(s)
- Danmeng Shuai
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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Søbjerg LS, Lindhardt AT, Skrydstrup T, Finster K, Meyer RL. Size control and catalytic activity of bio-supported palladium nanoparticles. Colloids Surf B Biointerfaces 2011; 85:373-8. [DOI: 10.1016/j.colsurfb.2011.03.014] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Revised: 02/19/2011] [Accepted: 03/15/2011] [Indexed: 10/18/2022]
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Xie Y, Cao H, Li Y, Zhang Y, Crittenden JC. Highly selective PdCu/amorphous silica-alumina (ASA) catalysts for groundwater denitration. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2011; 45:4066-4072. [PMID: 21473571 DOI: 10.1021/es104050h] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Catalytic nitrate reduction is a promising technology in groundwater purification. In this study, PdCu bimetallic catalysts supported on an industrial amorphous silica-alumina (ASA) were synthesized and used to simulate catalytic removal of nitrate in groundwater. The catalysts exhibited very high activity and the highest catalytic selectivity toward N₂O and N₂ was 90.2%. The optimal Pd/Cu weight ratio was four. Relatively low reduction temperature was found benefit the catalytic stability and 300 °C was the appropriate reduction temperature during catalyst preparation. With an average particle size 5.4 nm, the metal particles were very uniformly distributed on the catalyst surface prepared with the codeposition method. This kept the catalyst more stable than the PdCu/Al₂O₂ catalyst with larger metal particles. According to XRD, TEM, and XPS results, the metals maintained zero-valence but aggregated by about 2 nm during the denitration reaction, which caused gradual deactivation of the catalysts. Little leaching of Cu and Pd from the catalyst might also have a slightly negative impact to the stability of the catalysts. A simple treatment was found to redistribute the particles on the deactivated catalysts, and high catalytic activity was recovered after this process.
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Affiliation(s)
- Yongbing Xie
- National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing 100190, China
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Composite surfactants aided solvothermal synthesis and catalytic hydrogenation property of oil soluble bimetallic CoMoS nanoparticles. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/s1003-9953(09)60093-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Shuai D, Chaplin BP, Shapley JR, Menendez NP, McCalman DC, Schneider WF, Werth CJ. Enhancement of oxyanion and diatrizoate reduction kinetics using selected azo dyes on Pd-based catalysts. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2010; 44:1773-1779. [PMID: 20143806 DOI: 10.1021/es9029842] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Azo dyes are widespread pollutants and potential cocontaminants for nitrate; we evaluated their effect on catalytic reduction of a suite of oxyanions, diatrizoate, and N-nitrosodimethylamine (NDMA). The azo dye methyl orange significantly enhanced (less than or equal to a factor of 5.24) the catalytic reduction kinetics of nitrate, nitrite, bromate, perchlorate, chlorate, and diatrizoate with several different Pd-based catalysts; NDMA reduction was not enhanced. Nitrate was selected as a probe contaminant, and a variety of azo dyes (methyl orange, methyl red, fast yellow AB, metanil yellow, acid orange 7, congo red, eriochrome black T, acid red 27, acid yellow 11, and acid yellow 17) were evaluated for their ability to enhance reduction. Hydrogenation energies of azo dyes were calculated using density functional theory and a volcano relationship between hydrogenation energies and reduction rate enhancement was observed. A kinetic model based on Brønsted-Evans-Polanyi (BEP) theory matched the volcano relationship and suggests sorbed azo dyes enhance reduction kinetics through hydrogen atom shuttling between reduced azo dyes (i.e., hydrazo dyes) and oxyanions or diatrizoate. This is the first research that has identified this synergetic effect, and it has implications for designing more efficient catalysts and reducing Pd costs in water treatment systems.
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Affiliation(s)
- Danmeng Shuai
- Department of Civil and Environmental Engineering, Department of Chemistry, and Center of Advanced Materials for the Purification of Water with Systems, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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Chaplin BP, Schrader G, Farrell J. Electrochemical oxidation of N-nitrosodimethylamine with boron-doped diamond film electrodes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2009; 43:8302-8307. [PMID: 19924960 DOI: 10.1021/es901582q] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
This research investigated NDMA oxidation by boron-doped diamond (BDD) film electrodes. Oxidation rates were measured as a function of electrode potential, current density, and temperature using rotating disk and flow-through reactors. Final NDMA reaction products were carbon dioxide, ammonium, and nitrate, with dimethylamine and methylamine as intermediate products. Reaction rates were first-order with respect to NDMA concentration and surface area normalized oxidation rates as high as 850 +/- 50 L/m(2)-hr were observed at a current density of 10 mA/cm(2). The flow-through reactor yielded mass transfer limited reaction rates that were first-order in NDMA concentration, with a half-life of 2.1 +/- 0.1 min. Experimental evidence indicates that NDMA oxidation proceeds via a direct electron transfer at potentials >1.8 V/SHE with a measured apparent activation energy of 3.1 +/- 0.5 kJ/mol at a potential of 2.5 V/SHE. Density functional theory calculations indicate that a direct two-electron transfer can produce a stable NDMA((+2)) species that is stabilized by forming an adduct with water. The transfer of two electrons from NDMA to the electrode allows an activation-less attack of hydroxyl radicals on the NDMA((+2)) water adduct. At higher overpotentials the oxidation of NDMA occurs by a combination of direct electron transfer and hydroxyl radicals produced via water electrolysis.
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Affiliation(s)
- Brian P Chaplin
- Department of Chemical and Environmental Engineering, University of Arizona, Tucson, Arizona 85721, USA.
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Chaplin BP, Shapley JR, Werth CJ. Oxidative Regeneration of Sulfide-fouled Catalysts for Water Treatment. Catal Letters 2009. [DOI: 10.1007/s10562-009-0083-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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The Selectivity and Sustainability of a Pd–In/γ-Al2O3 Catalyst in a Packed-Bed Reactor: The Effect of Solution Composition. Catal Letters 2009. [DOI: 10.1007/s10562-009-9883-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Davie MG, Cheng H, Hopkins GD, Lebron CA, Reinhard M. Implementing heterogeneous catalytic dechlorination technology for remediating TCE-contaminated groundwater. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2008; 42:8908-8915. [PMID: 19192817 DOI: 10.1021/es8014919] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
To transition catalytic reductive dechlorination (CRD) into practice, it is necessary to demonstrate the effectiveness, robustness, and economic competitiveness of CRD-based treatment systems. A CRD system scaled up from previous laboratory studies was tested for remediating groundwater contaminated with 500-1200 microg L(-1) trichloroethylene (TCE) at Edwards Air Force Base (AFB), California. Groundwater was pumped from a treatment well at 2 gal min(-1), amended with hydrogen to 0.35 mg L(-1) and contacted for 2.3 min with 20 kg eggshell-coated Pd on alumina beads (2% Pd by wt) packed in a fixed-bed reactor, and then returned to the aquifer. Operation was continuous for 23 h followed a 1 h regeneration cycle. After regeneration, TCE removal was 99.8% for 4 to 9 h and then declined to 98.3% due to catalyst deactivation. The observed catalyst deactivation was tentatively attributed to formation of sulfidic compounds; modeling of catalyst deactivation kinetics suggests the presence of sulfidic species equivalent to 2-4 mg L(-1) hydrogen sulfide in the reactor water. Over the more than 100 day demonstration period, TCE concentrations in the treated groundwater were reduced by >99% to an average concentration of 4.1 microg L(-1). The results demonstrate CRD as a viable treatment alternative technically and economically competitive with activated carbon adsorption and other conventional physicochemical treatmenttechnologies.
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Affiliation(s)
- Matthew G Davie
- Department of Civil and Environmental Engineering, Stanford University, Stanford, California 94305-4020, USA
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Lim TT, Zhu BW. Effects of anions on the kinetics and reactivity of nanoscale Pd/Fe in trichlorobenzene dechlorination. CHEMOSPHERE 2008; 73:1471-1477. [PMID: 18760820 DOI: 10.1016/j.chemosphere.2008.07.050] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Revised: 07/22/2008] [Accepted: 07/23/2008] [Indexed: 05/26/2023]
Abstract
Influences of anionic co-solutes on dechlorination of 1,2,4-trichlorobenzene (124TCB) by the nanoscale Pd/Fe particles were investigated in batch experiments in the presence of an anionic solute such as nitrate, nitrite, perchlorate, phosphate, carbonate, silica, sulfate, sulfite, or sulfide. Based on the extent of inhibitory effects on the 124TCB dechlorination, the anions can be ranked in the order of: control≈sulfate≈silica<perchlorate<carbonate<nitrate<phosphate<nitrite<sulfite<sulfide. Mineralogical analysis with XRD, morphological study with SEM-EDX, and spectroscopic analysis with FTIR spectrometer of the fresh and reacted Pd/Fe samples were conducted to examine the influences of the various anions on the Pd/Fe surface. Silica and sulfate did not show any significant short-term effect on reactivity of the nanoscale Pd/Fe, because the 124TCB dechlorination reaction was only dependent on the reactivity of the Pd site that was apparently not passivated by the anions. However, sulfide and sulfite could immediately terminate the 124TCB dechlorination process. Based on the natures of their inhibitory effects on 124TCB dechlorination by the Pd/Fe, the anions can be classified as: (1) adsorption-precipitation passivating species (e.g., phosphate and carbonate), (2) redox-active species (e.g., nitrate, nitrite, and perchlorate), and (3) catalyst poisons (e.g., sulfide and sulfite).
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Affiliation(s)
- Teik-Thye Lim
- School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Republic of Singapore.
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Sakamoto Y, Wang C, Okuhara T, Kamiya Y. Catalytic Oxidation of Ammonium Ions with Nitrite Ions in Water over Metallic Platinum Supported on Titanium Dioxide at a Mild Reaction Temperature. CHEM LETT 2008. [DOI: 10.1246/cl.2008.1024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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42
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Angeles-Wedler D, Mackenzie K, Kopinke FD. Permanganate oxidation of sulfur compounds to prevent poisoning of Pd catalysts in water treatment processes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2008; 42:5734-5739. [PMID: 18754501 DOI: 10.1021/es800330s] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The practical application of Pd-catalyzed water treatment processes is impeded by catalyst poisoning by reduced sulfur compounds (RSCs). In this study, the potential of permanganate as a selective oxidant for the removal of microbially generated RSCs in water and as a regeneration agent for S-poisoned catalysts was evaluated. Hydrodechlorination using Pd/Al2O3 was carried out as a probe reaction in permanganate-pretreated water. The activity of the Pd catalysts in the successfully pretreated reaction medium was similar to that in deionized water. The catalyst showed no deactivation behavior in the presence of permanganate at a concentration level < or = 0.07 mM. With a residual oxidant concentration of > or = 0.08 mM, a significant but temporary inhibition of the catalytic dechlorination was observed. Unprotected Pd/Al2O3, which had been completely poisoned by sulfide, was reactivated by a combined treatment with permanganate and hydrazine. However, the anthropogenic water pollutants thiophene and carbon disulfide were resistant against permanganate. Together with the preoxidation of catalyst poisons, hydrophobic protection of the catalysts was studied. Pd/zeolite and various hydrophobically coated catalysts showed a higher stability against ionic poisons and permanganate than the uncoated catalyst. By means of a combination of oxidative water pretreatment and hydrophobic catalyst protection, we provide a new tool to harness the potential of Pd-catalyzed hydrodehalogenation for the treatment of real waters.
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Affiliation(s)
- Dalia Angeles-Wedler
- UFZ-Helmholtz-Centre for Environmental Research, Department of Environmental Technology, Permoserstrasse 15, 04318 Leipzig, Germany
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Highly Selective Hydrogenation of Nitrate to Harmless Compounds in Water Over Copper–Palladium Bimetallic Clusters Supported on Active Carbon. Catal Letters 2008. [DOI: 10.1007/s10562-008-9574-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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44
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Davie MG, Shih K, Pacheco FA, Leckie JO, Reinhard M. Palladium-indium catalyzed reduction of N-nitrosodimethylamine: indium as a promoter metal. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2008; 42:3040-3046. [PMID: 18497163 DOI: 10.1021/es7023115] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
An emerging technology for the removal of N-nitrosodimethylamine (NDMA) from drinking and groundwater is reductive destruction using noble metal catalysts and hydrogen gas as a reducing agent. Bimetallic palladium-indium (Pd-In) supported on alumina combines the ability of Into activate NDMA with the hydrogen activating properties of Pd. This study examined the effect of In addition to a commercial 5% Pd by weight on gamma-Al2O3 catalyst on the efficacy of NDMA reduction. The pseudo-first-order rate constant increased proportionately to In loading from 0.057 h(-1) for 0% In to a maximum of 0.25 h(-1) for 1% In and then decreased with additional in loading. Data suggest that hydrogen activation occurred only on Pd surfaces and In activated NDMA 20 times more effectively than Pd on a mass basis. The rate-limiting factor was NDMA activation for In loadings below 1%. The decrease at higher loadings is interpreted as In blocking pore spaces and limiting access to Pd sites, suggesting monatomic hydrogen limitation. The only products detected were dimethylamine and ammonium with carbon and nitrogen balances in excess of 92%, consistent with a mechanism involving reductive N-N bond cleavage. Results from this study serve as a basis for optimizing bimetallic catalysts for treating NDMA contaminated waters.
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Affiliation(s)
- Matthew G Davie
- Department of Civil & Environmental Engineering, Stanford University, Stanford, California 94305-4020, USA
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Knitt LE, Shapley JR, Strathmann TJ. Rapid metal-catalyzed hydrodehalogenation of Iodinated x-ray contrast media. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2008; 42:577-583. [PMID: 18284165 DOI: 10.1021/es071837y] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Iodinated X-ray contrast media (ICM) are detected in natural waters at high concentrations relative to other pharmaceuticals due to extensive use in medical diagnostics and high recalcitrance during conventional wastewater treatment. This study examines, for the first time, reductive treatment of ICM in water with hydrogen gas in combination with supported palladium and porous nickel catalysts. Kinetic experiments demonstrate rapid and complete hydrodehalogenation of both ionic (diatrizoate) and neutral (iopromide) ICM. Reaction rates in batch systems (continuous mixing, P(H2) = 0.1 MPa, 25 degrees C) appear to be surface-reaction controlled and are dependent upon catalyst identity (e.g., 5 wt % versus 1 wt % Pd/ Al2O3) as well as the concentration of ICM and catalyst. Reaction rates are not markedly affected by ICM structure, pH, or by the presence of many common ions (Na+, Ca2+, Mg2+, F-, Cl-, Br-, ClO4-, SO4(2-), HCO3-, and NO3-). In contrast, elevated concentrations of iodide, (bi)sulfide, and dissolved organic matter inhibit hydrodehalogenation of ICM. However, catalyst activity can be regained by washing the catalyst (e.g., with water, NaOCl, or alkaline solution). Catalytic reduction of ICM present in treated wastewater effluent is slower than in deionized water, but similar reaction rates are observed when the effluent is pretreated to reduce the level of dissolved organic matter. The high selectivity of reductive catalytic treatment processes suggest that this is a promising strategy for targeted treatment of ICM present in mixed waste streams and natural water matrices containing much higher concentrations of nontarget constituents.
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Affiliation(s)
- Lindsay E Knitt
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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