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Sun Y, Zhang Z, Heng J, Gao C, Jin Q, Chen Z, Guo Z. Co-transport of U(VI) and colloidal biochar in quartz sand heterogeneous media. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 816:151606. [PMID: 34774950 DOI: 10.1016/j.scitotenv.2021.151606] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 11/07/2021] [Accepted: 11/07/2021] [Indexed: 06/13/2023]
Abstract
Biochar has attracted much attention for remediating the sites contaminated with heavy metals and radionuclides due to its low cost and high adsorption affinity. However, little is known about how colloidal biochar influences U(VI) transport in the environment. In this study, column experiments were conducted to investigate the individual and co-transport of U(VI) and biochar colloids (BC) in quartz sand heterogeneous media. Results showed that the transport of U(VI) in the individual transport system was pH-dependent and insensitive to ionic strength, whereas the individual BC transport was more sensitive to the changes in ionic strength compared to those in pH, indicating that electrostatic interaction plays a major role during BC transport but chemical interaction dominates U(VI) transport. In the presence of BC, the transport of U(VI) was significantly facilitated because of U(VI) adsorption on BC. The existence of low concentration of U(VI) (2.5 × 10-6 M), however, did not affect the breakthrough curves (BTCs) of BC, except for the co-transport at relatively high ionic strength (100 mM) where BC transport was impeded due to the decrease of colloid suspension stability. Colloid size exclusion effect was evidenced by the evolution of particle size and zeta potential of the effluents. The transport of BC in both the individual and co-transport systems could be described by a two-site kinetic attachment/detachment model. This work implies that a risk assessment of BC facilitated heavy metal transport should be carefully considered when biochar is applied to the remediation of heavy metal contaminated sites.
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Affiliation(s)
- Yufeng Sun
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China
| | - Zhen Zhang
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China
| | - Jiaxi Heng
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China
| | - Chao Gao
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China
| | - Qiang Jin
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China; Frontiers Science Center for Rare Isotopes, Lanzhou University, 730000 Lanzhou, China; The Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, 730000 Lanzhou, China.
| | - Zongyuan Chen
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China; Frontiers Science Center for Rare Isotopes, Lanzhou University, 730000 Lanzhou, China; The Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, 730000 Lanzhou, China
| | - Zhijun Guo
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China; Frontiers Science Center for Rare Isotopes, Lanzhou University, 730000 Lanzhou, China; The Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, 730000 Lanzhou, China.
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Sun Y, Gao C, Jin Q, Chen Z, Guo Z. Effects of iron oxide coatings on the mobility and retardation of U(VI) in water saturated media. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2021.127458] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ge M, Wang D, Yang J, Jin Q, Chen Z, Wu W, Guo Z. Co-transport of U(VI) and akaganéite colloids in water-saturated porous media: Role of U(VI) concentration, pH and ionic strength. WATER RESEARCH 2018; 147:350-361. [PMID: 30321825 DOI: 10.1016/j.watres.2018.10.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 09/27/2018] [Accepted: 10/02/2018] [Indexed: 05/13/2023]
Abstract
Remediating uranium contamination becomes a worldwide interest because of increasing uranium release from mining activities. Due to ubiquitous presence of pyrite and the application of iron-based technology, colloidal iron oxy-hydroxides such as akaganéite colloid (AKC) extensively exist in uranium polluted water at uranium tailing sites. In this context, we studied individual and co-transport of U(VI) and AKC in water-saturated sand columns at 50 mg/L AKC and environmentally relevant U(VI) concentrations (5.0 × 10-7 ∼ 5.0 × 10-5 M). It was found that, in addition to the impact of pH and ionic strength, whether AKC facilitated U(VI) transport depended on U(VI) concentration as well. The presence of AKC facilitated U(VI) transport at relatively low U(VI) concentration (5.0 × 10-7 ∼ 5.0 × 10-6 M), which was due to the strong adsorption of U(VI) on AKC and faster transport of AKC than that U(VI) as observed in their individual transport experiments. At relatively high U(VI) concentrations (5.0 × 10-5 M), however, AKC impeded U(VI) transport because U(VI) of high concentration decreased AKC colloidal stability and increased AKC aggregation and attachment. Thus, U(VI) and AKC co-transport was even blocked completely at relatively high pH and ionic strength. The mechanisms behind the co-transport of U(VI) and AKC were also confirmed by assessing the evolutions of aqueous pH and AKC zeta potential and particle size distribution in the column effluents. A two-site non-equilibrium model and a two-site kinetic attachment/detachment model well-described the breakthrough curves of U(VI) and AKC, respectively. Knowledge generated from this study provides a thorough understanding of uranium transport in the absence/presence of AKC, and brings new insights into the influence of contaminant concentration on co-transport in the presence of colloids.
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Affiliation(s)
- Mengtuan Ge
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000, Lanzhou, China
| | - Dengjun Wang
- National Research Council Resident Research Associate at the U.S. Environmental Protection Agency, 919 Kerr Research Drive, Ada, OK, 74820, USA
| | - Junwei Yang
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000, Lanzhou, China
| | - Qiang Jin
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000, Lanzhou, China
| | - Zongyuan Chen
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000, Lanzhou, China; The Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, 730000 Lanzhou, China.
| | - Wangsuo Wu
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000, Lanzhou, China; The Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, 730000 Lanzhou, China
| | - Zhijun Guo
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000, Lanzhou, China; The Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, 730000 Lanzhou, China.
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Sun Z, Chen D, Chen B, Kong L, Su M. Enhanced uranium(VI) adsorption by chitosan modified phosphate rock. Colloids Surf A Physicochem Eng Asp 2018. [DOI: 10.1016/j.colsurfa.2018.02.043] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Wen H, Pan Z, Giammar D, Li L. Enhanced Uranium Immobilization by Phosphate Amendment under Variable Geochemical and Flow Conditions: Insights from Reactive Transport Modeling. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:5841-5850. [PMID: 29648808 DOI: 10.1021/acs.est.7b05662] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Phosphate amendment has shown promise for enhancing uranium immobilization. The mechanism of the enhancement, however, has remained unclear with contrasting observations under variable environmental conditions. A dual-domain reactive transport model is developed here with constraints from batch and column experimental data to understand the mechanisms and to explore the effectiveness of enhanced U(VI) immobilization under variable geochemical and flow conditions. Modeling results indicate that under low U(VI) conditions in natural waters, phosphate addition promotes U(VI) immobilization through the formation of U(VI)-phosphate ternary surface complexes and the precipitation of calcium phosphate, both decreasing the concentrations of mobile U-Ca-CO3 aqueous complexes. This contrasts with previous hypotheses attributing the immobilization enhancement to U(VI)-phosphate precipitation under experimental conditions with high U(VI). Sensitivity analysis shows that phosphate is effective under relatively low Ca (<0.1 mM) and total inorganic carbon (TIC) (<0.5 mM) conditions, where >60% of U(VI) still remains on sediments after 113 residence times of flushing with low phosphate solutions (<0.1 mM). Under high Ca or TIC conditions, a similar level of U(VI) immobilization can be achieved only when the phosphate concentration is higher than Ca or TIC concentrations. Compared to the strong geochemical effects, flow conditions have relatively limited impacts on U(VI) immobilization. These results explain contrasting field observations on the effectiveness of phosphate amendment and offer capabilities to extrapolate observations to other environmental conditions.
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Affiliation(s)
- Hang Wen
- Department of Civil and Environmental Engineering , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Zezhen Pan
- Department of Energy, Environmental and Chemical Engineering , Washington University in St. Louis , St. Louis , Missouri 63130 , United States
| | - Daniel Giammar
- Department of Energy, Environmental and Chemical Engineering , Washington University in St. Louis , St. Louis , Missouri 63130 , United States
| | - Li Li
- Department of Civil and Environmental Engineering , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
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Du L, Li S, Li X, Wang P, Huang Z, Tan Z, Liu C, Liao J, Liu N. Effect of humic acid on uranium(VI) retention and transport through quartz columns with varying pH and anion type. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2017; 177:142-150. [PMID: 28667877 DOI: 10.1016/j.jenvrad.2017.06.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 06/11/2017] [Accepted: 06/17/2017] [Indexed: 06/07/2023]
Abstract
Humic acid (HA)1 is ubiquitous in the environment and is an important factor in the migration behavior of U(VI) in the geological medium. The present work investigated the effect of HA on the migration behavior of U(VI) using quartz column experiments at different pH values and in the presence of various anions. The U(VI) adsorption characteristics and speciation were also studied to illuminate further the migration behavior of U(VI). Our results indicated that, at pH 6.0, HA slightly increased the migration velocity of U(VI) during the initial phase and reduced the quantity of eluted U(VI) because of the formation of HA-U(VI). The relative concentration (c/c0) of U(VI)was higher in the HA-U system at pH 8.0 than that at pH 5.0 because of the higher solubility of HA in basic solutions and the difference in charge of HA-U(VI). In the U-HA-anion system at pH 6.0, the breakthrough pore volumes (PVs2) of U(VI) in electrolytes containing Cl- and SO42- anions (PV = 8) are much higher than for solutions containing phosphate (PV = 3), while the HA migration behavior was not significantly affected by the type of anion. Thus, the fast migration of U(VI) under HA and phosphate was attributed to phosphate rather than HA. This result suggests that phosphate should be given more attention in predictions of U(VI) migration, especially in regions with high groundwater phosphate content.
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Affiliation(s)
- Liang Du
- Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, PR China; Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, PR China
| | - Shicheng Li
- Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, PR China
| | - Xiaolong Li
- Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, PR China
| | - Ping Wang
- Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, PR China
| | - Zhaoya Huang
- Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, PR China
| | - Zhaoyi Tan
- Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, PR China
| | - Chunli Liu
- Beijing National Laboratory for Molecular Science (BNLMS), College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China
| | - Jiali Liao
- Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, PR China
| | - Ning Liu
- Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, PR China.
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Soltanian MR, Ritzi RW, Dai Z, Huang CC. Reactive solute transport in physically and chemically heterogeneous porous media with multimodal reactive mineral facies: the Lagrangian approach. CHEMOSPHERE 2015; 122:235-244. [PMID: 25532767 DOI: 10.1016/j.chemosphere.2014.11.064] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 11/14/2014] [Accepted: 11/26/2014] [Indexed: 06/04/2023]
Abstract
Physical and chemical heterogeneities have a large impact on reactive transport in porous media. Examples of heterogeneous attributes affecting reactive mass transport are the hydraulic conductivity (K), and the equilibrium sorption distribution coefficient (Kd). This paper uses the Deng et al. (2013) conceptual model for multimodal reactive mineral facies and a Lagrangian-based stochastic theory in order to analyze the reactive solute dispersion in three-dimensional anisotropic heterogeneous porous media with hierarchical organization of reactive minerals. An example based on real field data is used to illustrate the time evolution trends of reactive solute dispersion. The results show that the correlation between the hydraulic conductivity and the equilibrium sorption distribution coefficient does have a significant effect on reactive solute dispersion. The anisotropy ratio does not have a significant effect on reactive solute dispersion. Furthermore, through a sensitivity analysis we investigate the impact of changing the mean, variance, and integral scale of K and Kd on reactive solute dispersion.
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Affiliation(s)
- Mohamad Reza Soltanian
- Department of Earth and Environmental Sciences, Wright State University, Dayton, OH 45435, United States.
| | - Robert W Ritzi
- Department of Earth and Environmental Sciences, Wright State University, Dayton, OH 45435, United States.
| | - Zhenxue Dai
- EES-16, Earth and Environmental Sciences Division, Los Alamos National Laboratory, Mailstop T003, Los Alamos, NM 87545, United States.
| | - Chao Cheng Huang
- Department of Mathematics and Statistic, Wright State University, 3640 Colonel Glenn Hwy, Dayton, OH 45435-0001, United States.
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Wang Q, Cheng T, Wu Y. Influence of mineral colloids and humic substances on uranium(VI) transport in water-saturated geologic porous media. JOURNAL OF CONTAMINANT HYDROLOGY 2014; 170:76-85. [PMID: 25444118 DOI: 10.1016/j.jconhyd.2014.10.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2014] [Revised: 09/19/2014] [Accepted: 10/06/2014] [Indexed: 05/13/2023]
Abstract
Mineral colloids and humic substances often co-exist in subsurface environment and substantially influence uranium (U) transport. However, the combined effects of mineral colloids and humic substances on U transport are not clear. This study is aimed at quantifying U transport and elucidating geochemical processes that control U transport when both mineral colloids and humic acid (HA) are present. U-spiked solutions/suspensions were injected into water-saturated sand columns, and U and colloid concentrations in column effluent were monitored. We found that HA promoted U transport via (i) formation of aqueous U-HA complexes, and (ii) competition against aqueous U for surface sites on transport media. Illite colloids had no influence on U transport at pH5 in the absence of HA due to low mobility of the colloids. At pH9, U desorbed from mobile illite and the presence of illite decreased U transport. At pH5, high U transport occurred when both illite colloids and HA were present, which was attributed to enhanced U adsorption to illite colloids via formation of ternary illite-HA-U surface complexes, and enhanced illite transport due to HA attachment to illite and transport media. This study demonstrates that the combined effects of mineral colloids and HA on contaminant transport is different from simple addition of the individual effect.
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Affiliation(s)
- Qing Wang
- Environmental Science Program, Faculty of Science, Memorial University, St. John's, Newfoundland and Labrador A1B 3X7, Canada
| | - Tao Cheng
- Department of Earth Sciences, Memorial University, St. John's, Newfoundland and Labrador A1B 3X5, Canada.
| | - Yang Wu
- Department of Earth Sciences, Memorial University, St. John's, Newfoundland and Labrador A1B 3X5, Canada
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Liu H, Chen T, Frost RL. An overview of the role of goethite surfaces in the environment. CHEMOSPHERE 2014; 103:1-11. [PMID: 24332732 DOI: 10.1016/j.chemosphere.2013.11.065] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 11/24/2013] [Accepted: 11/26/2013] [Indexed: 05/26/2023]
Abstract
Goethite, one of the most thermodynamically stable iron oxides, has been extensively researched especially the structure (including surface structure), the adsorption capacity to anions, organic/organic acid (especially for the soil organic carbon) and cations in the natural environment and its potential application in environmental protection. For example, the adsorption of heavy metals by goethite can decrease the concentration of heavy metals in aqueous solution and immobilize; the adsorption to soil organic carbon can decrease the release of carbon and fix carbon. In this present overview, the possible physicochemical properties of the goethite surface contributing to the strong affinity of goethite to nutrients and contaminants in natural environment are reported. Moreover, these chemicals adsorbed by goethite were also summarized and the suggested adsorption mechanism for these adsorbates was elucidated, which will help us understand the role of goethite in natural environment and provide some information about goethite as an absorbent. In addition, the feasibility of goethite used as catalyst carrier and the precursor of NZVI was proposed for removal of environmental pollution.
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Affiliation(s)
- Haibo Liu
- Laboratory for Nanomineralogy and Environmental Material, School of Resources & Environmental Engineering, Hefei University of Technology, China; School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, Australia
| | - Tianhu Chen
- Laboratory for Nanomineralogy and Environmental Material, School of Resources & Environmental Engineering, Hefei University of Technology, China.
| | - Ray L Frost
- School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, Australia.
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Deng H, Dai Z, Wolfsberg AV, Ye M, Stauffer PH, Lu Z, Kwicklis E. Upscaling retardation factor in hierarchical porous media with multimodal reactive mineral facies. CHEMOSPHERE 2013; 91:248-257. [PMID: 23260249 DOI: 10.1016/j.chemosphere.2012.10.105] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 10/29/2012] [Accepted: 10/31/2012] [Indexed: 06/01/2023]
Abstract
Aquifer heterogeneity controls spatial and temporal variability of reactive transport parameters and has significant impacts on subsurface modeling of flow, transport, and remediation. Upscaling (or homogenization) is a process to replace a heterogeneous domain with a homogeneous one such that both reproduce the same response. To make reliable and accurate predictions of reactive transport for contaminant in chemically and physically heterogeneous porous media, subsurface reactive transport modeling needs upscaled parameters such as effective retardation factor to perform field-scale simulations. This paper develops a conceptual model of multimodal reactive mineral facies for upscaling reactive transport parameters of hierarchical heterogeneous porous media. Based on the conceptual model, covariance of hydraulic conductivity, sorption coefficient, flow velocity, retardation factor, and cross-covariance between flow velocity and retardation factor are derived from geostatistical characterizations of a three-dimensional unbounded aquifer system. Subsequently, using a Lagrangian approach the scale-dependent analytical expressions are derived to describe the scaling effect of effective retardation factors in temporal and spatial domains. When time and space scales become sufficiently large, the effective retardation factors approximate their composite arithmetic mean. Correlation between the hydraulic conductivity and the sorption coefficient can significantly affect the values of the effective retardation factor in temporal and spatial domains. When the temporal and spatial scales are relatively small, scaling effect of the effective retardation factors is relatively large. This study provides a practical methodology to develop effective transport parameters for field-scale modeling at which remediation and risk assessment is actually conducted. It does not only bridge the gap between bench-scale measurements to field-scale modeling, but also provide new insights into the influence of hierarchical mineral distribution on effective retardation factor.
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Affiliation(s)
- Hailin Deng
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, EES-16, T003, Los Alamos, NM 87545, United States.
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Li D, Kaplan DI. Sorption coefficients and molecular mechanisms of Pu, U, Np, Am and Tc to Fe (hydr)oxides: a review. JOURNAL OF HAZARDOUS MATERIALS 2012; 243:1-18. [PMID: 23141377 DOI: 10.1016/j.jhazmat.2012.09.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 09/05/2012] [Accepted: 09/07/2012] [Indexed: 06/01/2023]
Abstract
Pu, U, Np, Am and Tc are among the major risk drivers at nuclear waste management facilities throughout the world. Furthermore, uranium mining and milling operations have generated an enormous legacy of radioactively contaminated soils and groundwater. The sorption process of radionulcides onto ubiquitous Fe (hydr)oxides (FHOs; hematite, magnetite, goethite and ferrihydrite) is one of the most vital geochemical processes controlling the transport and fate of radionuclides and nuclear wastes in the subsurface zones. Meanwhile, understanding molecular-level chemical speciation of radionuclides onto FHOs is crucial to model their behavior in subsurface environments, and to develop new technologies for nuclear waste treatment and long-term remediation strategies for contaminated soils and groundwater. This review article aims (1) to provide risk or performance assessment modelers with macroscopic distribution coefficient (K(d)) data of Pu, U, Np, Am and Tc onto FHOs under different conditions (pH, radionuclide concentration, solution ion strength, sorbent loading, partial pressure of CO(2) (P CO(2)), equilibrium time) pertinent to environmental and engineered systems, and (2) to provide a microscopic or molecular-level understanding of the chemical speciation and sorption processes of these radionuclides to FHOs.
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Affiliation(s)
- Dien Li
- Savannah River National Laboratory, Aiken, SC 29802, USA.
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Effects of phosphate and fulvic acid on the sorption and transport of uranium(VI) on silica column. J Radioanal Nucl Chem 2008. [DOI: 10.1007/s10967-007-7177-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Sani RK, Peyton BM, Dohnalkova A. Comparison of uranium(VI) removal by Shewanella oneidensis MR-1 in flow and batch reactors. WATER RESEARCH 2008; 42:2993-3002. [PMID: 18468655 DOI: 10.1016/j.watres.2008.04.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Revised: 03/21/2008] [Accepted: 04/01/2008] [Indexed: 05/26/2023]
Abstract
To better understand the interactions among metal contaminants, nutrients, and microorganisms in subsurface fracture-flow systems, biofilms of pure culture of Shewanella oneidensis MR-1 were grown in six fracture-flow reactors (FFRs) of different geometries. The spatial and temporal distribution of uranium and bacteria were examined using a tracer dye (brilliant blue FCF) and microscopy. The results showed that plugging by bacterial cells was dependent on the geometry of the reactor and that biofilms grown in FFRs had a limited U(VI)-reduction capacity. To quantify the U(VI)-reduction capacity of biofilms, batch experiments for U(VI) reduction were performed with repetitive U(VI) additions. U(VI)-reduction rates of stationary phase cultures decreased after each U(VI) addition. After the fourth U(VI) addition, stationary phase cultures treated with U(VI) with and without spent medium yielded gray and black precipitates, respectively. These gray and black U precipitates were analyzed using high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. Data for randomly selected areas of black precipitates showed that reduced U particles (3-6 nm) were crystalline, whereas gray precipitates were a mixture of crystalline and amorphous solids. Results obtained in this study, including a dramatic limitation of S. oneidensis MR-1 and its biofilms to reduce U(VI) and plugging of FFRs, suggest that alternative organisms should be targeted for stimulation for metal immobilization in subsurface fracture-flow systems.
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Affiliation(s)
- Rajesh K Sani
- Department of Chemical and Biological Engineering, South Dakota School of Mines and Technology, Rapid City, SD 57701, USA.
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