采用液相还原法制备纳米零价铁（nZVI），用来去除溶液中的 U （Ⅵ），讨论了溶液pH值、nZVI质量浓度、接触反应时间和温度对去除效果的影响，并从nZVI对U （Ⅵ）的还原角度探讨了还原动力学规律。研究结果表明：nZVI对溶液中的U （Ⅵ...采用液相还原法制备纳米零价铁（nZVI），用来去除溶液中的 U （Ⅵ），讨论了溶液pH值、nZVI质量浓度、接触反应时间和温度对去除效果的影响，并从nZVI对U （Ⅵ）的还原角度探讨了还原动力学规律。研究结果表明：nZVI对溶液中的U （Ⅵ）有很好的去除效果，其去除过程包括还原沉淀和吸附，其中还原过程符合准一级还原动力学模型；溶液pH值对去除效果有明显的影响，在溶液pH值为5.0时，去除率达到最大值96.27％。温度对去除效果有一定的影响，表观速率常数 kobs随反应温度的升高而增大，还原速率与反应温度的关系符合Arrhenius定律，反应活化能 Ea 为16.54 kJ/mol ，低于一般化学反应的活化能（60～250 kJ/mol），表明该反应较易进行。展开更多
Stable isotope probing （SIP） was used to identify microbes stimulated by ethanol addition in microcosms containing two sediments collected from the bioremediation test zone at the US Department of Energy Oak Ridge s...Stable isotope probing （SIP） was used to identify microbes stimulated by ethanol addition in microcosms containing two sediments collected from the bioremediation test zone at the US Department of Energy Oak Ridge site, TN, USA. One sample was highly bioreduced with ethanol while another was less reduced. Microcosms with the respective sediments were amended with ^13C labeled ethanol and incubated for 7 days for SIP. Ethanol was rapidly converted to acetate within 24h accompanied with the reduction of nitrate and sulfate. The accumulation of acetate persisted beyond the 7 d period. Aqueous U did not decline in the microcosm with the reduced sediment due to desorption of U but continuously declined in the less reduced sample. Microbial growth and concomitant 13C-DNA production was detected when ethanol was exhausted and abundant acetate had accumulated in both microcosms. This coincided with U（VI） reduction in the less reduced sample. I3C originating from ethanol was ultimately utilized for growth, either directly or indirectly, by the dominant microbial community members within 7 days of incubation. The microbial community was comprised predominantly of known denitrifiers, sulfate-reducing bacteria and iron （Ⅲ） reducing bacteria including Desulfovibrio, Sphingomonas, Ferribacterium, Rhodanobacter, Geothrix, Thiobacillus and others, including the known U（VI）-redueing bacteria Acidovorax, Anaeromyxobacter, Desulfovibrio, Geobac- ter and Desulfosporosinus. The findings suggest that ethanol biostimulates the U（VI）-reducing microbial com- munity by first serving as an electron donor for nitrate, sulfate, iron （IH） and U（VI） reduction, and acetate which then functions as electron donor for U（VI） reduction and carbon source for microbial growth.展开更多
In this work,we proposed a new U(Ⅵ)removal strategy combining adsorption and photocatalytic reduction by the PMo_(12)/UiO-66 heterojunctions.The PMo_(12)has been encapsulated in the cavities of Ui O-66 by a one-step ...In this work,we proposed a new U(Ⅵ)removal strategy combining adsorption and photocatalytic reduction by the PMo_(12)/UiO-66 heterojunctions.The PMo_(12)has been encapsulated in the cavities of Ui O-66 by a one-step hydrothermal method,and the PMo_(12)/UiO-66 exhibited high adsorption capacity and photocatalytic activity.The maximal theoretical sorption capacity of U(Ⅵ)on 15%PMo_(12)/UiO-66 reached225.36 mg/g and the photoreduction rate of 15%PMo_(12)/UiO-66 is about thirty times as much as UiO-66.Under the light irradiation,the photogenerated electrons rapidly transport from UiO-66 to PMo_(12),and the photo-generated electrons could efficiently reduce the pre-enriched U(Ⅵ)to U(IV).This work provides new insights into remediation of the radioactive environment.展开更多
Uranium bio-transformations are the many and varying types of interactions that microbes can have with uranium encountered in their environment. In this review, bio-transformations, including reduction, oxidation, res...Uranium bio-transformations are the many and varying types of interactions that microbes can have with uranium encountered in their environment. In this review, bio-transformations, including reduction, oxidation, respiration, sorption, mineralization, accumulation, precipitation, biomarkers, and sensors are defined and discussed. Consensus and divergences are noted in bioavailability, mechanism of uranium reduction, environment, metabolism and the type of organism. The breadth of organisms with characterized bio-trans formations is also cataloged and discussed. We further debate if uranium biotransformations provide bio-protection or bio-benefit to the microbe and highlight the need for more work in the field to understand if microbes use uranium reduction for energy gain and growth, as having the ability is separate from exercising it. The presentation centers on the fundamental drivers for these processes with an additional exposition of the essential contribution of inorganic chemistry techniques to the molecular characterization of these biological processes.展开更多
通过液相还原法制备岩棉负载纳米零价铁(Nano zero-valent iron loaded on rock wool,RW/nZVI),并利用X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)等手段对其物质组成及微观形貌进行表征。以对溶液中U(Ⅵ)的去除能力为...通过液相还原法制备岩棉负载纳米零价铁(Nano zero-valent iron loaded on rock wool,RW/nZVI),并利用X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)等手段对其物质组成及微观形貌进行表征。以对溶液中U(Ⅵ)的去除能力为考核指标,运用等温吸附模型和动力学模型研究其去除溶液中U(Ⅵ)的机理。结果表明,岩棉负载可以明显改善纳米零价铁的团聚,且对溶液中U(Ⅵ)有较好的去除效果,其吸附等温线符合Langmuir模型,模拟最大吸附量为79.681 mg/g,动力学过程符合准二级吸附动力学和准一级还原动力学,表明吸附为单分子层吸附,且是通过吸附和还原作用去除溶液中的U(Ⅵ)。展开更多
基金The authors thank Benli Chai for bioinformatic support and Anthony Gaca and Ami Smith for technical assistance in the laboratory. This study was funded by the US DOE Office of Science under grants DE-FG02-97ER62469, DE-FG02-97ER64398, AC05-00OR22725, and DE-SC0006783. Mary Beth Leigh was supported by a US National Science Foundation postdoctoral fellowship in Microbial Biology.
文摘Stable isotope probing （SIP） was used to identify microbes stimulated by ethanol addition in microcosms containing two sediments collected from the bioremediation test zone at the US Department of Energy Oak Ridge site, TN, USA. One sample was highly bioreduced with ethanol while another was less reduced. Microcosms with the respective sediments were amended with ^13C labeled ethanol and incubated for 7 days for SIP. Ethanol was rapidly converted to acetate within 24h accompanied with the reduction of nitrate and sulfate. The accumulation of acetate persisted beyond the 7 d period. Aqueous U did not decline in the microcosm with the reduced sediment due to desorption of U but continuously declined in the less reduced sample. Microbial growth and concomitant 13C-DNA production was detected when ethanol was exhausted and abundant acetate had accumulated in both microcosms. This coincided with U（VI） reduction in the less reduced sample. I3C originating from ethanol was ultimately utilized for growth, either directly or indirectly, by the dominant microbial community members within 7 days of incubation. The microbial community was comprised predominantly of known denitrifiers, sulfate-reducing bacteria and iron （Ⅲ） reducing bacteria including Desulfovibrio, Sphingomonas, Ferribacterium, Rhodanobacter, Geothrix, Thiobacillus and others, including the known U（VI）-redueing bacteria Acidovorax, Anaeromyxobacter, Desulfovibrio, Geobac- ter and Desulfosporosinus. The findings suggest that ethanol biostimulates the U（VI）-reducing microbial com- munity by first serving as an electron donor for nitrate, sulfate, iron （IH） and U（VI） reduction, and acetate which then functions as electron donor for U（VI） reduction and carbon source for microbial growth.
基金financially supported by the National Natural Science Foundation of China(Nos.21866004,21866003,22066003,22076022,22006004)the Defense Industrial Technology Development Program(No.JCKY2019401C004)+2 种基金the Open Fund of Jiangxi Province Key Laboratory of Synthetic Chemistry(No.JXSC202012)the Open Fund of State Key Laboratory of Nuclear Resources and Environment(No.NRE1924)the Graduate Innovation Fund of East China University of Technology(No.DHYC-202134)。
文摘In this work,we proposed a new U(Ⅵ)removal strategy combining adsorption and photocatalytic reduction by the PMo_(12)/UiO-66 heterojunctions.The PMo_(12)has been encapsulated in the cavities of Ui O-66 by a one-step hydrothermal method,and the PMo_(12)/UiO-66 exhibited high adsorption capacity and photocatalytic activity.The maximal theoretical sorption capacity of U(Ⅵ)on 15%PMo_(12)/UiO-66 reached225.36 mg/g and the photoreduction rate of 15%PMo_(12)/UiO-66 is about thirty times as much as UiO-66.Under the light irradiation,the photogenerated electrons rapidly transport from UiO-66 to PMo_(12),and the photo-generated electrons could efficiently reduce the pre-enriched U(Ⅵ)to U(IV).This work provides new insights into remediation of the radioactive environment.
文摘Uranium bio-transformations are the many and varying types of interactions that microbes can have with uranium encountered in their environment. In this review, bio-transformations, including reduction, oxidation, respiration, sorption, mineralization, accumulation, precipitation, biomarkers, and sensors are defined and discussed. Consensus and divergences are noted in bioavailability, mechanism of uranium reduction, environment, metabolism and the type of organism. The breadth of organisms with characterized bio-trans formations is also cataloged and discussed. We further debate if uranium biotransformations provide bio-protection or bio-benefit to the microbe and highlight the need for more work in the field to understand if microbes use uranium reduction for energy gain and growth, as having the ability is separate from exercising it. The presentation centers on the fundamental drivers for these processes with an additional exposition of the essential contribution of inorganic chemistry techniques to the molecular characterization of these biological processes.
文摘通过液相还原法制备岩棉负载纳米零价铁(Nano zero-valent iron loaded on rock wool,RW/nZVI),并利用X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)等手段对其物质组成及微观形貌进行表征。以对溶液中U(Ⅵ)的去除能力为考核指标,运用等温吸附模型和动力学模型研究其去除溶液中U(Ⅵ)的机理。结果表明,岩棉负载可以明显改善纳米零价铁的团聚,且对溶液中U(Ⅵ)有较好的去除效果,其吸附等温线符合Langmuir模型,模拟最大吸附量为79.681 mg/g,动力学过程符合准二级吸附动力学和准一级还原动力学,表明吸附为单分子层吸附,且是通过吸附和还原作用去除溶液中的U(Ⅵ)。
