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Liu P, Shen Z, Cheng J, Han Z, Xu W, Ji M, Ma F. 1-aza-18-crown-6 ether tailored graphene oxide for Cs(I) removal from wastewater. RADIOCHIM ACTA 2022. [DOI: 10.1515/ract-2022-0068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Due to the relative abundance, long half-life and high mobility of radioactive cesium (Cs), new adsorbents are urgently needed to treat Cs to ensure public health. In this study, a graphene oxide (GO) based adsorbent for Cs(I) adsorption was prepared by 1-aza-18-crown-6 ether modification. XRD, FT-IR, XPS and SEM results showed that the properties of 1-aza-18-crown 6 ether modified GO (18C6-GO) changed dramatically compared with that of raw graphite. The adsorption properties of 18C6-GO for Cs(I) were studied by batch static adsorption experiments. The results showed that the adsorption equilibrium time of 18C6-GO was 20 h. Kinetic study revealed that the adsorption rate of Cs(I) conformed to pseudo-second-order kinetic model. Langmuir adsorption isotherm simulation indicated that the adsorption arises at homogeneous adsorption sites on 18C6-GO. Therefore, crown ether modified GO may have implications for the treatment of wastewater.
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Affiliation(s)
- Peng Liu
- Yantai Research Institute and Graduate School, Harbin Engineering University , Yantai 264006 , China
- College of Nuclear Science and Technology, Harbin Engineering University , Harbin 150001 , China
| | - Zhuang Shen
- College of Nuclear Science and Technology, Harbin Engineering University , Harbin 150001 , China
| | - Jiaxian Cheng
- Yantai Research Institute and Graduate School, Harbin Engineering University , Yantai 264006 , China
| | - Zhen Han
- Yantai Research Institute and Graduate School, Harbin Engineering University , Yantai 264006 , China
| | - Wenda Xu
- Yantai Standard Metrology Inspection & Test Center, National Steam Flowrate Measurement , Yantai 264000 , China
| | - Mingbo Ji
- Yantai Research Institute and Graduate School, Harbin Engineering University , Yantai 264006 , China
- College of Nuclear Science and Technology, Harbin Engineering University , Harbin 150001 , China
| | - Fuqiu Ma
- Yantai Research Institute and Graduate School, Harbin Engineering University , Yantai 264006 , China
- College of Nuclear Science and Technology, Harbin Engineering University , Harbin 150001 , China
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Surface complexation modeling of the effects of dissolved inorganic carbon on adsorption of U(VI) onto Fe3O4 nanoparticles coated with lignite humic acid. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2021.127260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Hu Z, Guo W. Fibrous Phase Red Phosphorene as a New Photocatalyst for Carbon Dioxide Reduction and Hydrogen Evolution. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2008004. [PMID: 33792191 DOI: 10.1002/smll.202008004] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Revised: 03/08/2021] [Indexed: 06/12/2023]
Abstract
2D photocatalysts are one of the hottest issues in energy and material science. In the field of photocatalysis, a 2D material with an appropriate bandgap of 1.3 to 2.0 eV is desirable. Herein, a new kind of fibrous phase red phosphorene with a bandgap between 1.43 to 1.54 eV is obtained. This is much better than black phosphorus because the bandgap of black P depends of its layer number. The black P needs to be as thin as 1-2 layers for suitable band diagram, which is difficult to control. The fibrous red phosphorene is first used for photocatalytic CO2 reduction, and its activity is superior to the majority of mainstream photocatalysts and reaches a record-high value among phosphorus. Besides, its activity in hydrogen evolution is higher than most of the phosphorus photocatalysts. The intralayer charge transfer is much easier than interlayer transfer. The mobility of electron and hole along the phosphorene plane is about 20 times higher than that perpendicular to different layers. The activity sites is at region between the two P[21] chains. These regions are easy to be exposed for fibrous phase phosphorene, making it to exhibit high activity.
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Affiliation(s)
- Zhuofeng Hu
- School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou, China
| | - Weiqing Guo
- School of Environmental and Chemical Engineering, Foshan University, Foshan, 528000, China
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U(VI) adsorption to Fe3O4 nanoparticles coated with lignite humic acid: Experimental measurements and surface complexation modeling. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2021.126150] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Boulanger N, Kuzenkova AS, Iakunkov A, Romanchuk AY, Trigub AL, Egorov AV, Bauters S, Amidani L, Retegan M, Kvashnina KO, Kalmykov SN, Talyzin AV. Enhanced Sorption of Radionuclides by Defect-Rich Graphene Oxide. ACS APPLIED MATERIALS & INTERFACES 2020; 12:45122-45135. [PMID: 32902246 PMCID: PMC7684581 DOI: 10.1021/acsami.0c11122] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 09/09/2020] [Indexed: 06/11/2023]
Abstract
Extremely defect graphene oxide (dGO) is proposed as an advanced sorbent for treatment of radioactive waste and contaminated natural waters. dGO prepared using a modified Hummers oxidation procedure, starting from reduced graphene oxide (rGO) as a precursor, shows significantly higher sorption of U(VI), Am(III), and Eu(III) than standard graphene oxides (GOs). Earlier studies revealed the mechanism of radionuclide sorption related to defects in GO sheets. Therefore, explosive thermal exfoliation of graphite oxide was used to prepare rGO with a large number of defects and holes. Defects and holes are additionally introduced by Hummers oxidation of rGO, thus providing an extremely defect-rich material. Analysis of characterization by XPS, TGA, and FTIR shows that dGO oxygen functionalization is predominantly related to defects, such as flake edges and edge atoms of holes, whereas standard GO exhibits oxygen functional groups mostly on the planar surface. The high abundance of defects in dGO results in a 15-fold increase in sorption capacity of U(VI) compared to that in standard Hummers GO. The improved sorption capacity of dGO is related to abundant carboxylic group attached hole edge atoms of GO flakes as revealed by synchrotron-based extended X-ray absorption fine structure (EXAFS) and high-energy resolution fluorescence detected X-ray absorption near edge structure (HERFD-XANES) spectroscopy.
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Affiliation(s)
| | - Anastasiia S. Kuzenkova
- Department
of Chemistry, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia
| | - Artem Iakunkov
- Department
of Physics, Umeå University, S-90187 Umeå, Sweden
| | - Anna Yu. Romanchuk
- Department
of Chemistry, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia
| | - Alexander L. Trigub
- Department
of Chemistry, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia
- National
Research Centre “Kurchatov Institute”, Moscow 123098, Russia
| | - Alexander V. Egorov
- Department
of Chemistry, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia
| | - Stephen Bauters
- The
Rossendorf Beamline at ESRF − The
European Synchrotron, CS40220, 38043 Grenoble Cedex 9, France
- Helmholtz
Zentrum Dresden-Rossendorf (HZDR), Institute
of Resource Ecology, P. O. Box 510119, 01314 Dresden, Germany
| | - Lucia Amidani
- The
Rossendorf Beamline at ESRF − The
European Synchrotron, CS40220, 38043 Grenoble Cedex 9, France
- Helmholtz
Zentrum Dresden-Rossendorf (HZDR), Institute
of Resource Ecology, P. O. Box 510119, 01314 Dresden, Germany
| | - Marius Retegan
- The
European
Synchrotron, CS40220, 38043 Grenoble Cedex 9, France
| | - Kristina O. Kvashnina
- Department
of Chemistry, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia
- The
Rossendorf Beamline at ESRF − The
European Synchrotron, CS40220, 38043 Grenoble Cedex 9, France
- Helmholtz
Zentrum Dresden-Rossendorf (HZDR), Institute
of Resource Ecology, P. O. Box 510119, 01314 Dresden, Germany
| | - Stepan N. Kalmykov
- Department
of Chemistry, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia
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Ma J, Wang C, Zhao Q, Ren J, Chen Z, Wang J. Interaction of U(vi) with α-MnO2@layered double hydroxides by combined batch experiments and spectroscopy studies. Inorg Chem Front 2020. [DOI: 10.1039/c9qi01316d] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Uranium is of high concern in the field of environmental remediation because of its high fluidity, radioactivity, biological toxicity and long life. Removing U(vi) from wastewater is of great significance to both environment and biology.
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Affiliation(s)
- Junping Ma
- MOE Key Laboratory of Resources and Environmental Systems Optimization
- College of Environmental Science and Engineering
- North China Electric Power University
- Beijing 102206
- PR China
| | - Chen Wang
- MOE Key Laboratory of Resources and Environmental Systems Optimization
- College of Environmental Science and Engineering
- North China Electric Power University
- Beijing 102206
- PR China
| | - Qiuyu Zhao
- MOE Key Laboratory of Resources and Environmental Systems Optimization
- College of Environmental Science and Engineering
- North China Electric Power University
- Beijing 102206
- PR China
| | - Jianlin Ren
- MOE Key Laboratory of Resources and Environmental Systems Optimization
- College of Environmental Science and Engineering
- North China Electric Power University
- Beijing 102206
- PR China
| | - Zhe Chen
- MOE Key Laboratory of Resources and Environmental Systems Optimization
- College of Environmental Science and Engineering
- North China Electric Power University
- Beijing 102206
- PR China
| | - Jianjun Wang
- MOE Key Laboratory of Resources and Environmental Systems Optimization
- College of Environmental Science and Engineering
- North China Electric Power University
- Beijing 102206
- PR China
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Gupta NK, Choudhary BC, Gupta A, Achary S, Sengupta A. Graphene-based adsorbents for the separation of f-metals from waste solutions: A review. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.111121] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Highly efficient uranium(VI) removal from aqueous solution using poly(cyclotriphosphazene-co-4,4′-diaminodiphenyl-ether) crosslinked microspheres. J Radioanal Nucl Chem 2019. [DOI: 10.1007/s10967-019-06681-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Wang X, Chen L, Wang L, Fan Q, Pan D, Li J, Chi F, Xie Y, Yu S, Xiao C, Luo F, Wang J, Wang X, Chen C, Wu W, Shi W, Wang S, Wang X. Synthesis of novel nanomaterials and their application in efficient removal of radionuclides. Sci China Chem 2019; 62:933-967. [DOI: https:/doi.org/10.1007/s11426-019-9492-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 05/05/2019] [Indexed: 06/25/2023]
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Synthesis of novel nanomaterials and their application in efficient removal of radionuclides. Sci China Chem 2019. [DOI: 10.1007/s11426-019-9492-4] [Citation(s) in RCA: 168] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Lan T, Liao J, Yang Y, Chai Z, Liu N, Wang D. Competition/Cooperation between Humic Acid and Graphene Oxide in Uranyl Adsorption Implicated by Molecular Dynamics Simulations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:5102-5110. [PMID: 30945863 DOI: 10.1021/acs.est.9b00656] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Molecular dynamics (MD) simulations were performed to investigate the influence of curvature and backbone rigidity of an oxygenated surface, here graphene oxide (GO), on its adsorption of uranyl in collaboration with humic acid (HA). The planar curvature of GO was found to be beneficial in impeding the folding of HA. This, together with its rigidity that helps stabilize the extended conformation of HA, offered rich binding sites to interact with uranyl with only marginal loss of binding strength. According to our simulations, the interaction between uranyl and GO was mainly driven by electrostatic interactions. The presence of HA not only provided multiple sites to compete/cooperate with GO for adsorption of free uranyl but also interacted with GO acting as a "bridge" to connect uranyl and GO. The potential of mean force (PMF) profiles implied that HA significantly enhanced the interaction strength between uranyl and GO and stabilized the uranyl-GO complex. Meanwhile, GO could reduce the diffusion coefficients of uranyl and HA and retard their migrations in aqueous solution. This work provides theoretical hints on the GO-based remediation strategies for the sites contaminated by uranium or other heavy metal ions and oxygenated organic pollutants.
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Affiliation(s)
- Tu Lan
- Key Laboratory of Radiation Physics and Technology (Sichuan University), Ministry of Education, Institute of Nuclear Science and Technology , Sichuan University , Chengdu 610064 , China
- CAS Key Laboratory of Nuclear Radiation and Nuclear Techniques, Multidisciplinary Initiative Center , Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049 , China
- Department of Chemical and Materials Engineering , University of Alberta , Edmonton , Alberta T6G 1H9 , Canada
| | - Jiali Liao
- Key Laboratory of Radiation Physics and Technology (Sichuan University), Ministry of Education, Institute of Nuclear Science and Technology , Sichuan University , Chengdu 610064 , China
| | - Yuanyou Yang
- Key Laboratory of Radiation Physics and Technology (Sichuan University), Ministry of Education, Institute of Nuclear Science and Technology , Sichuan University , Chengdu 610064 , China
| | - Zhifang Chai
- CAS Key Laboratory of Nuclear Radiation and Nuclear Techniques, Multidisciplinary Initiative Center , Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049 , China
- State Key Laboratory of Radiation Medicine and Protection, Soochow University, and School of Radiation Medicine and Interdisciplinary Sciences (RAD-X) , Soochow University , Suzhou 215123 , China
| | - Ning Liu
- Key Laboratory of Radiation Physics and Technology (Sichuan University), Ministry of Education, Institute of Nuclear Science and Technology , Sichuan University , Chengdu 610064 , China
| | - Dongqi Wang
- CAS Key Laboratory of Nuclear Radiation and Nuclear Techniques, Multidisciplinary Initiative Center , Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049 , China
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Alam MS, Gorman-Lewis D, Chen N, Safari S, Baek K, Konhauser KO, Alessi DS. Mechanisms of the Removal of U(VI) from Aqueous Solution Using Biochar: A Combined Spectroscopic and Modeling Approach. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:13057-13067. [PMID: 30339395 DOI: 10.1021/acs.est.8b01715] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Biochar has been touted as a promising sorbent for the removal of inorganic contaminants, such as uranium (U), from water. However, the molecular-scale mechanisms of aqueous U(VI) species adsorption to biochar remain poorly understood. In this study, two approaches, grounded in equilibrium thermodynamics, were employed to investigate the U(VI) adsorption mechanisms: (1) batch U(VI) adsorption experiments coupled to surface complexation modeling (SCM) and (2) isothermal titration calorimetry (ITC), supported by synchrotron-based X-ray absorption spectroscopy (XAS) analyses. The biochars tested have considerable proton buffering capacity and most strongly adsorb U(VI) between approximately pH 4 and 6. FT-IR and XPS studies, along with XAS analyses, show that U(VI) adsorption occurs primarily at the proton-active carboxyl (-COOH) and phenolic hydroxyl (-OH) functional groups on the biochar surface. The SCM approach is able to predict U(VI) adsorption behavior across a wide range of pH and at varying initial U(VI) and biochar concentrations, and U adsorption is strongly influenced by aqueous U(VI) speciation. Supporting ITC measurements indicate that the calculated enthalpies of protonation reactions of the studied biochar, as well as the adsorption of U(VI), are consistent with anionic oxygen ligands and are indicative of both inner- and outer-sphere complexation. Our results provide new insights into the modes of U(VI) adsorption by biochar and more generally improve our understanding of its potential to remove radionuclides from contaminated waters.
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Affiliation(s)
- Md Samrat Alam
- Department of Earth and Atmospheric Sciences , University of Alberta , 1-26 Earth Sciences Building , Alberta , T6G 2E3 , Canada
| | - Drew Gorman-Lewis
- Department of Earth and Space Sciences , University of Washington , Johnson Hall Rm-070, Box 351310, 4000 15th Avenue NE , Seattle , Washington 98195 , United States
| | - Ning Chen
- Canadian Light Source Inc. , University of Saskatchewan , 114 Science Plane , Saskatoon , Saskatchewan S7N 0X4 , Canada
| | - Salman Safari
- Department of Earth and Atmospheric Sciences , University of Alberta , 1-26 Earth Sciences Building , Alberta , T6G 2E3 , Canada
| | - Kitae Baek
- Department of Environmental Engineering and Soil Environment Research Center , Chonbuk National University , 567 Baekje-daero , Deokjin-gu, Jeonju , Jeollabuk-do 54896 , Republic of Korea
| | - Kurt O Konhauser
- Department of Earth and Atmospheric Sciences , University of Alberta , 1-26 Earth Sciences Building , Alberta , T6G 2E3 , Canada
| | - Daniel S Alessi
- Department of Earth and Atmospheric Sciences , University of Alberta , 1-26 Earth Sciences Building , Alberta , T6G 2E3 , Canada
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Xie Y, Powell BA. Linear Free Energy Relationship for Actinide Sorption to Graphene Oxide. ACS APPLIED MATERIALS & INTERFACES 2018; 10:32086-32092. [PMID: 30160935 DOI: 10.1021/acsami.8b08478] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Th(IV) and Np(V) sorption to graphene oxide (GO) was studied as a function of pH from 0-7.5 and analyte concentrations (0.01-1 mg/L for Th(IV) at pH 3 and 0.005-10 mg/L for Np(V) at pH 7). Starting at pH 1, greater than 90% Th(IV) sorption to GO occurred while significant Np(V) sorption to GO started at pH 5. Surface complexation modeling (SCM) using an electrostatic double layer model simultaneously modeled Th(IV) and Np(V) sorption to GO over the pH and the analyte concentration ranges. The SCM indicated that Th(IV) complexation to sulfonate sites dominated at a low pH 0-3 and its complexation to carboxylate sites dominated at a higher pH 3-7.5. In contrast, Np(V) showed a stronger affinity for sulfonate sites than carboxylate sites over the pH and concentration ranges examined in this work. Combining the results from a previous study on Eu(III) and U(VI) sorption to GO, the affinities of actinide/lanthanide sorption to GO was found to follow the trend in actinide/lanthanide ion effective charges (e.g., Th4+ (+4) > UO22+ (+3.2) > Eu3+ (+3) > NpO2+ (+2.2)), which is similar to actinide sorption to iron oxides and clay minerals. Moreover, a linear free energy relationship was observed between the stability constants for actinides and Eu(III) (with the oxidation state from III to VI) complexation to carboxylate sites on GO and the stability constants for their complexation to carbonate.
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In-situ reduction synthesis of manganese dioxide@polypyrrole core/shell nanomaterial for highly efficient enrichment of U(VI) and Eu(III). Sci China Chem 2018. [DOI: 10.1007/s11426-017-9225-5] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Zhao H, Wang Y, Zhang D, Cheng H, Wang Y. Electrochromatographic performance of graphene and graphene oxide modified silica particles packed capillary columns. Electrophoresis 2018; 39:933-940. [DOI: 10.1002/elps.201700435] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 12/06/2017] [Accepted: 12/08/2017] [Indexed: 12/14/2022]
Affiliation(s)
- Hongyan Zhao
- College of Material Chemistry and Chemical Engineering; Hangzhou Normal University; Hangzhou P. R. China
| | - Yizhou Wang
- Qianjiang College; Hangzhou Normal University; Hangzhou P. R. China
| | - Danyu Zhang
- College of Material Chemistry and Chemical Engineering; Hangzhou Normal University; Hangzhou P. R. China
| | - Heyong Cheng
- College of Material Chemistry and Chemical Engineering; Hangzhou Normal University; Hangzhou P. R. China
| | - Yuanchao Wang
- College of Material Chemistry and Chemical Engineering; Hangzhou Normal University; Hangzhou P. R. China
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Showalter AR, Duster TA, Szymanowski JES, Na C, Fein JB, Bunker BA. An X-ray absorption fine structure spectroscopy study of metal sorption to graphene oxide. J Colloid Interface Sci 2017; 508:75-86. [PMID: 28822863 DOI: 10.1016/j.jcis.2017.08.040] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 07/24/2017] [Accepted: 08/12/2017] [Indexed: 01/20/2023]
Abstract
Remediation and prevention of environmental contamination by toxic metals is an ongoing issue. Additionally, improving water filtration systems is necessary to prevent toxic metals from circulating through the water supply. Graphene oxide (GO) is a highly sorptive material for a variety of heavy metals under different ionic strength conditions over a wide pH range, making it a promising candidate for use in metal adsorption from contaminated sites or in filtration systems. We present X-ray absorption fine structure (XAFS) spectroscopy results investigating the binding environment of Cd (II), U(VI) and Pb(II) ions onto multi-layered graphene oxide (MLGO). This study shows that the binding environment of each metal onto the MLGO is unique, with different behaviors governing the sorption as a function of pH. For Cd sorption to MLGO, the same mechanism of electrostatic attraction between the MLGO and the Cd+2 ions surrounded by water molecules prevails over the entire pH range studied. The U(VI), present in solution as the uranyl ion, shows only subtle changes as a function of pH, likely due to the varied speciation of uranium in solution. The adsorption of the U to the MLGO is through a covalent, inner-sphere bond. The only metal from this study where the dominant adsorption mechanism to the MLGO changes with pH is Pb. In this case, under lower pH conditions, Pb is bound onto the MLGO through dominantly outer-sphere, electrostatic adsorption, while under higher pH conditions, the bonding changes to be dominated by inner-sphere, covalent adsorption. Since each of the metals in this study show unique binding properties, it is possible that MLGO could be engineered to effectively adsorb specific metal ions from solution and optimize environmental remediation or filtration for each metal.
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Affiliation(s)
- Allison R Showalter
- Department of Physics, 225 Nieuwland Science Hall, University of Notre Dame, Notre Dame, IN 46556, USA.
| | - Thomas A Duster
- Department of Civil and Environmental Engineering and Earth Sciences, 156 Fitzpatrick Hall, University of Notre Dame, Notre Dame, IN 46556, USA.
| | - Jennifer E S Szymanowski
- Department of Civil and Environmental Engineering and Earth Sciences, 156 Fitzpatrick Hall, University of Notre Dame, Notre Dame, IN 46556, USA.
| | - Chongzheng Na
- Department of Civil and Environmental Engineering and Earth Sciences, 156 Fitzpatrick Hall, University of Notre Dame, Notre Dame, IN 46556, USA.
| | - Jeremy B Fein
- Department of Civil and Environmental Engineering and Earth Sciences, 156 Fitzpatrick Hall, University of Notre Dame, Notre Dame, IN 46556, USA.
| | - Bruce A Bunker
- Department of Physics, 225 Nieuwland Science Hall, University of Notre Dame, Notre Dame, IN 46556, USA.
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