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Yu C, Luong NT, Hefni ME, Song Z, Högfors-Rönnholm E, Engblom S, Xie S, Chernikov R, Broström M, Boily JF, Åström ME. Storage and Distribution of Organic Carbon and Nutrients in Acidic Soils Developed on Sulfidic Sediments: The Roles of Reactive Iron and Macropores. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:9200-9212. [PMID: 38743440 PMCID: PMC11137870 DOI: 10.1021/acs.est.3c11007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 04/11/2024] [Accepted: 05/07/2024] [Indexed: 05/16/2024]
Abstract
In a boreal acidic sulfate-rich subsoil (pH 3-4) developing on sulfidic and organic-rich sediments over the past 70 years, extensive brownish-to-yellowish layers have formed on macropores. Our data reveal that these layers ("macropore surfaces") are strongly enriched in 1 M HCl-extractable reactive iron (2-7% dry weight), largely bound to schwertmannite and 2-line ferrihydrite. These reactive iron phases trap large pools of labile organic matter (OM) and HCl-extractable phosphorus, possibly derived from the cultivated layer. Within soil aggregates, the OM is of a different nature from that on the macropore surfaces but similar to that in the underlying sulfidic sediments (C-horizon). This provides evidence that the sedimentary OM in the bulk subsoil has been largely preserved without significant decomposition and/or fractionation, likely due to physiochemical stabilization by the reactive iron phases that also existed abundantly within the aggregates. These findings not only highlight the important yet underappreciated roles of iron oxyhydroxysulfates in OM/nutrient storage and distribution in acidic sulfate-rich and other similar environments but also suggest that boreal acidic sulfate-rich subsoils and other similar soil systems (existing widely on coastal plains worldwide and being increasingly formed in thawing permafrost) may act as global sinks for OM and nutrients in the short run.
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Affiliation(s)
- Changxun Yu
- Department
of Biology and Environmental Science, Linnaeus
University, 39231 Kalmar, Sweden
| | | | - Mohammed E. Hefni
- Department
of Chemistry and Biomedical Sciences, Linnaeus
University, 39231 Kalmar, Sweden
| | - Zhaoliang Song
- Institute
of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China
| | - Eva Högfors-Rönnholm
- Research
and Development, Novia University of Applied
Sciences, 65200 Vaasa, Finland
| | - Sten Engblom
- Research
and Development, Novia University of Applied
Sciences, 65200 Vaasa, Finland
| | - Shurong Xie
- School
of
Earth Sciences, East China University of
Technology, Nanchang 330013, China
| | - Roman Chernikov
- Canadian
Light Source, 44 Innovation
Boulevard, Saskatoon, Saskatchewan S7N 2 V3, Canada
| | - Markus Broström
- Thermochemical
Energy Conversion Laboratory, Department of Applied Physics and Electronics, Umeå University, 90187 Umeå, Sweden
| | | | - Mats E. Åström
- Department
of Biology and Environmental Science, Linnaeus
University, 39231 Kalmar, Sweden
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2
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Yang W, Zhang L, Li M, Zhang T, Liu Y, Liu J. KOH-modified bamboo charcoal loaded with α-FeOOH for efficient adsorption of copper and fluoride ions from aqueous solution. RSC Adv 2023; 13:30176-30189. [PMID: 37849693 PMCID: PMC10577395 DOI: 10.1039/d3ra05315f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 10/09/2023] [Indexed: 10/19/2023] Open
Abstract
In this work, bamboo charcoal (BC) is prepared by pyrolysis of bamboo. Then, KOH modification and surface deposition of Goethite (α-FeOOH) are performed to obtain a new KOH-modified BC loaded with α-FeOOH (FKBC) adsorbent for copper (Cu2+) and fluoride (F-) ion adsorption from aqueous solution. Surface morphology and physiochemical properties of the prepared adsorbent are characterized by scanning electron microscopy-energy dispersive spectrometer, X-ray diffraction, and N2 adsorption-desorption. The effect of pH, contact time, adsorbent dosage, and initial concentration on Cu2+ and F- adsorption is also investigated. In addition, adsorption kinetics and isotherms are fitted to pseudo-second-order kinetics and Langmuir model, respectively. Thermodynamic parameters suggest that the adsorption process is spontaneous and endothermic. The adsorption mechanism is further characterized by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The Cu2+ absorption mainly occurs through ion exchange, coordination reactions, and surface precipitation, while the F- adsorption mainly occurs via ion exchange and hydrogen bonding. The selective adsorption experiments reveal that FKBC has good selectivity for Cu2+ and F-. The adsorption-desorption experimental results indicate that FKBC can be reused for Cu2+ and F- adsorption after regeneration. Results indicate that FKBC can be a promising adsorbent for Cu2+ and F- removal from aqueous solutions.
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Affiliation(s)
- Wei Yang
- School of Environmental Science and Engineering, Hubei Polytechnic University Huangshi 435003 Hubei China
| | - Lei Zhang
- MWR Standard & Quality Control Research Institute Hangzhou 310024 Zhejiang China
| | - Meng Li
- School of Civil Engineering and Architecture, Wuhan University of Technology Wuhan 430070 Hubei China
| | - Ting Zhang
- School of Environmental Science and Engineering, Hubei Polytechnic University Huangshi 435003 Hubei China
| | - Yue Liu
- School of Environmental Science and Engineering, Hubei Polytechnic University Huangshi 435003 Hubei China
| | - Juan Liu
- School of Environmental Science and Engineering, Hubei Polytechnic University Huangshi 435003 Hubei China
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3
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Gao J, Han H, Gao C, Wang Y, Dong B, Xu Z. Organic amendments for in situ immobilization of heavy metals in soil: A review. CHEMOSPHERE 2023:139088. [PMID: 37268229 DOI: 10.1016/j.chemosphere.2023.139088] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Revised: 05/24/2023] [Accepted: 05/29/2023] [Indexed: 06/04/2023]
Abstract
There is a growing need for soil remediation due to the increase in heavy metals (HMs) migrating into the soil environment, especially those from man-made sources dominated by industry and agriculture. In situ immobilization technology, because of its lower life cycle environmental footprint, can achieve "green and sustainable remediation" of soil heavy-metal pollution. Among the various in situ immobilization remediation agents, organic amendments (OAs) stand out as they can act as soil conditioners while acting as HMs immobilization agents, and therefore have excellent application prospects. In this paper, the types and remediation effects of OAs for HMs in situ immobilization in soil are summarized. OAs have an important effect on the soil environment and other active substances in soil while interacting with HMs in soil. Based on these factors, the principle and mechanism of HMs in situ immobilization in soil using OAs are summarized. Given the complex differential characteristics of soil itself, it is impossible to determine whether it can remain stable after heavy-metal remediation; therefore, there is still a gap in knowledge regarding the compatibility and long-term effectiveness of OAs with soil. In the future, it is necessary to develop a reasonable HMs contamination remediation program for in situ immobilization and long-term monitoring through interdisciplinary integration techniques. These findings are expected to provide a reference for the development of advanced OAs and their applications in engineering.
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Affiliation(s)
- Jun Gao
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China.
| | - Haoxuan Han
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Chang Gao
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Yuhao Wang
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Bin Dong
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China; College of Environmental Science and Engineering, Guilin University of Technology, Guilin, 541006, China.
| | - Zuxin Xu
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China
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4
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Herath A, Datta DK, Bonyadinejad G, Salehi M. Partitioning of heavy metals in sediments and microplastics from stormwater runoff. CHEMOSPHERE 2023; 332:138844. [PMID: 37156285 DOI: 10.1016/j.chemosphere.2023.138844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 04/30/2023] [Accepted: 05/02/2023] [Indexed: 05/10/2023]
Abstract
Microplastics could act as vehicles for transporting heavy metals from urban environments to water resources via stormwater runoff. Although the transport of heavy metals by sediments has been widely studied, there is a lack of mechanistic understanding of their competition with microplastics (MPs) for heavy metal uptake. Therefore, this study was conducted to examine the partitioning of heavy metals in microplastics and sediments from stormwater runoff. For this purpose, new low density polyethylene (LDPE) pellets were selected as representative MPs, and accelerated UV-B irradiation experiments were conducted for eight weeks to generate photodegraded MPs. The competition of Cu, Zn, and Pb species for the occupation of available surface sites on sediments and new and photodegraded LDPE MPs was examined through 48 h kinetics experiments. Additionally, leaching experiments were conducted to identify the extent of organics released into the contact water by new and photodegraded MPs. Moreover, 24 h metal exposure experiments were conducted to identify the role of initial metal concentrations on their accumulation onto the MPs and sediments. The photodegradation process altered the LDPE MPs' surface chemistry by creating the oxidized carbon functional groups [>CO, >C-O-C<], and it also enhanced their dissolved organic carbon (DOC) leaching into the contact water. The results showed significantly greater levels of Cu, Zn, and Pb accumulations on photodegraded MPs compared to the new MPs in either absence or presence of sediments. Heavy metal uptake by sediments when photodegraded MPs were present was significantly reduced. This might be due to the organic matter leached by photodegraded MPs into the contact water.
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Affiliation(s)
- Amali Herath
- Department of Civil Engineering, The University of Memphis, Memphis, TN, USA
| | - Dibya Kanti Datta
- Department of Civil and Environmental Engineering, The University of Missouri, Columbia, MO, USA
| | | | - Maryam Salehi
- Department of Civil and Environmental Engineering, The University of Missouri, Columbia, MO, USA.
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Szewczuk-Karpisz K, Rzepa G, Bajda T, Wiśniewska M, Urban T, Kukowska S, Tomczyk A, Grygorczuk-Płaneta K, Kondracki B. Aggregation mechanism of natural schwertmannite particles covered with two-component layers of high molecular weight tackifier and trace metal ions. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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6
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Liu B, Lu H, Wu S, Wang Z, Feng L, Zheng H. Octopus tentacle-like molecular chains in magnetic flocculant enhances the removal of Cu(II) and malachite green in water. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2021.120139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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7
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Enhanced catalytic activation of H2O2 by CNTs/SCH through rapid Fe(III)/Fe(II) redox couple circulation: Insights into the role of functionalized multiwalled CNTs. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2021.120000] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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8
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Ulatowska J, Stala Ł, Polowczyk I. Comparison of Cr(VI) Adsorption Using Synthetic Schwertmannite Obtained by Fe 3+ Hydrolysis and Fe 2+ Oxidation: Kinetics, Isotherms and Adsorption Mechanism. Int J Mol Sci 2021; 22:8175. [PMID: 34360943 PMCID: PMC8348447 DOI: 10.3390/ijms22158175] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 07/17/2021] [Accepted: 07/23/2021] [Indexed: 11/19/2022] Open
Abstract
Good sorption properties and simple synthesis route make schwertmannite an increasingly popular adsorbent. In this work, the adsorption properties of synthetic schwertmannite towards Cr(VI) were investigated. This study aimed to compare the properties and sorption performance of adsorbents obtained by two methods: Fe3+ hydrolysis (SCHA) and Fe2+ oxidation (SCHB). To characterise the sorbents before and after Cr(VI) adsorption, specific surface area, particle size distribution, density, and zeta potential were determined. Additionally, optical micrographs, SEM, and FTIR analyses were performed. Adsorption experiments were performed in varying process conditions: pH, adsorbent dosage, contact time, and initial concentration. Adsorption isotherms were fitted by Freundlich, Langmuir, and Temkin models. Pseudo-first-order, pseudo-second-order, intraparticle diffusion, and liquid film diffusion models were used to fit the kinetics data. Linear regression was used to estimate the parameters of isotherm and kinetic models. The maximum adsorption capacity resulting from the fitted Langmuir isotherm is 42.97 and 17.54 mg·g-1 for SCHA and SCHB. Results show that the adsorption kinetics follows the pseudo-second-order kinetic model. Both iron-based adsorbents are suitable for removing Cr(VI) ions from aqueous solutions. Characterisation of the adsorbents after adsorption suggests that Cr(VI) adsorption can be mainly attributed to ion exchange with SO42- groups.
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Affiliation(s)
- Justyna Ulatowska
- Department of Process Engineering and Technology of Polymer and Carbon Materials, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego Street 27, 50-370 Wrocław, Poland; (Ł.S.); (I.P.)
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9
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Kim D, Ren Y, Cui M, Lee Y, Kim J, Kwon O, Ji W, Khim J. Arsenic adsorption on two types of powdered and beaded coal mine drainage sludge adsorbent. CHEMOSPHERE 2021; 272:129560. [PMID: 33460828 DOI: 10.1016/j.chemosphere.2021.129560] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/03/2021] [Accepted: 01/04/2021] [Indexed: 06/12/2023]
Abstract
The aim of this study was to evaluate the performance of a new adsorbent in terms of beading the sludge generated from coal mine drainage or arsenic removed from water is treated by electro-purification (EP) and chemical-precipitation (CP) methods. Batch experiments were conducted to study the influence of experimental parameters such as pH and temperature, as well as the mechanism of arsenic adsorption with the new adsorbent. The porosity of coal mine drainage sludge (CMDS)-beaded adsorbent made of chitosan and alginate was optimized by adding NaHCO3 powder to generate CO2 gas during the preparation process. Two types of adsorbents, beaded EP Najeon CMDS (BCMDSEP-NJ) and beaded CP Yeongdong CMDS (BCMDSCP-YD), were prepared by heating. The specific surface areas of the powdered adsorbents CMDSEP-NJ and CMDSCP-YD were 104 and 231 m2 g-1, respectively. The prepared beaded adsorbents BCMDSEP-NJ and BCMDSCP-YD had good porosity and specific surface areas of 16.8 and 21.2 m2 g-1, respectively. The X-ray diffraction results showed that the structure was goethite (aragonite) and schwertmannite. The pseudo second-order, intra-particle, and Langmuir models were used to explain the adsorption process. The qmax values of As(III) with BCDMSEP-NJ and BCMDSCP-YD adsorbents are 4.31 and 4.58 mg g-1, respectively and those of AS(V) are 9.31 and 10.93 mg g-1, respectively. The adsorption capacity for As(III) increased with increasing pH, whereas that for As(V) decreased. The activation energy was 8 kJ mol-1 or more. The mechanism of adsorption of arsenic using a beaded adsorbent was chemical adsorption followed by diffusion. The results of the present study suggest that new adsorbents can be effectively utilized for arsenic removal from water.
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Affiliation(s)
- Dongik Kim
- School of Civil, Environmental, and Architectural Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Yangmin Ren
- School of Civil, Environmental, and Architectural Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Mingcan Cui
- School of Civil, Environmental, and Architectural Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea.
| | - Yonghyeon Lee
- School of Civil, Environmental, and Architectural Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Jeonggwan Kim
- Korea Environmental Industry and Technology, 215 Jinheung-no, Eunpyeong-gu, Seoul, 03367, Republic of Korea
| | - Ohhun Kwon
- Mine Reclamation Corporation, 2, Segye-ro, Wonju-si, Gangwon-do, 26464, Republic of Korea
| | - Wonhyun Ji
- Mine Reclamation Corporation, 2, Segye-ro, Wonju-si, Gangwon-do, 26464, Republic of Korea
| | - Jeehyeong Khim
- School of Civil, Environmental, and Architectural Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea.
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10
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Zheng C, Wu Q, Hu X, Wang Y, Chen Y, Zhang S, Zheng H. Adsorption behavior of heavy metal ions on a polymer-immobilized amphoteric biosorbent: Surface interaction assessment. JOURNAL OF HAZARDOUS MATERIALS 2021; 403:123801. [PMID: 33264904 DOI: 10.1016/j.jhazmat.2020.123801] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 08/20/2020] [Accepted: 08/21/2020] [Indexed: 06/12/2023]
Abstract
Here we unveiled a novel magnetically separable amphoteric biosorbent (PD-Fe3O4@CCS) and investigated its adsorption behavior toward two classes of heavy metals, hexavalent chromium (Cr(VI)) and copper (Cu(II)) ions from water. Results indicated that the adsorption behavior of PD-Fe3O4@CCS for Cr(VI) was well described by Langmuir model; while for Cu(II) adsorption, the Freundlich model was the better one. Based on the kinetic results, both Cr(VI) and Cu(II) adsorption on PD-Fe3O4@CCS fitted well with the pseudo-second-order kinetic model. To evaluate the reusability and stability of PD-Fe3O4@CCS, regeneration tests were carried out for five cycles. Furthermore, the applicable feasibility of PD-Fe3O4@CCS in the real water matrix (including the single and binary pollutant systems) was studied, and results suggested the promising potential of PD-Fe3O4@CCS for large-scale application. Apart from these, the surface interactions between PD-Fe3O4@CCS and heavy metal ions in single and binary systems were systematically investigated based on FTIR and XPS analyses, which provided an essential implication for comprehending the interactions between biosorbents and contaminants in wastewater.
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Affiliation(s)
- Chaofan Zheng
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China; Chongqing Engineering Research Center of Water Treatment Coagulant, Chongqing 400045, China
| | - Qinzhen Wu
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China; Chongqing Engineering Research Center of Water Treatment Coagulant, Chongqing 400045, China
| | - Xuebin Hu
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China
| | - Yongjuan Wang
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China; Chongqing Engineering Research Center of Water Treatment Coagulant, Chongqing 400045, China
| | - Yi Chen
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China
| | - Shixin Zhang
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China; Chongqing Engineering Research Center of Water Treatment Coagulant, Chongqing 400045, China
| | - Huaili Zheng
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China; Chongqing Engineering Research Center of Water Treatment Coagulant, Chongqing 400045, China.
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11
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Yang Z, Karczewska-Golec J, Styczynski M, Bajda T, Drewniak L. Characterization of Fe-based sediments received from chemical pre-treatment of hydrometallurgical waste leachate from the recycling of alkaline batteries. JOURNAL OF HAZARDOUS MATERIALS 2021; 403:123988. [PMID: 33265027 DOI: 10.1016/j.jhazmat.2020.123988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 04/21/2020] [Accepted: 09/12/2020] [Indexed: 06/12/2023]
Abstract
The waste leachate from the hydrometallurgical recycling of spent batteries contains a significant amount of undesirable iron that needs to be precipitated before the recovery of target metals. The produced Fe-sediments are usually disposed of or stored at the treatment site as waste and are often poorly managed. This work estimates the environmental stability and application potential of Fe-sediments produced from highly acidic hydrometallurgical leachate during the recycling of spent alkaline batteries. After pH neutralization of the leachate by Na2CO3, a primary Fe-sediment (PFS), mainly composed of highly unstable metal (i.e., Fe, Zn, and Mn) sulfates, was obtained. The subsequent rinsing of this unstable PFS sediment led to the production of a secondary Fe-sediment (SFS), which was composed of an amorphous-phased ferric iron sulfate hydrate - Fe16O16(SO4)3(OH)10·10H2O. The results of single extraction using chemical reagents and biological dissolution by iron-transforming bacteria confirmed that despite most of the ions in PFS were dissolvable, the processed SFS was environmentally safe. The sorption efficiency of SFS towards Pb(II) and As(V) (up to ~ 99% and 94%, respectively, with an initial concentration of 100 mg/L) was found to be promising, suggesting the high potential for economical reuse of SFS.
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Affiliation(s)
- Zhendong Yang
- Institute of Microbiology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland
| | - Joanna Karczewska-Golec
- Institute of Microbiology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland
| | - Michal Styczynski
- Institute of Microbiology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland
| | - Tomasz Bajda
- AGH University of Science and Technology in Krakow, Faculty of Geology, Geophysics and Environmental Protection, al. A. Mickiewicza 30, 30-059 Krakow, Poland
| | - Lukasz Drewniak
- Institute of Microbiology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland.
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12
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Du H, Peacock CL, Chen W, Huang Q. Binding of Cd by ferrihydrite organo-mineral composites: Implications for Cd mobility and fate in natural and contaminated environments. CHEMOSPHERE 2018; 207:404-412. [PMID: 29803890 DOI: 10.1016/j.chemosphere.2018.05.092] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 05/13/2018] [Accepted: 05/15/2018] [Indexed: 05/26/2023]
Abstract
Adsorption and coprecipitation of organic matter with iron (hydr)oxides can alter iron (hydr)oxide surface properties and their reactivity towards nutrient elements and heavy metals. Organo-mineral composites were synthesized using humic acid (HA) and iron oxide, during coprecipitation with ferrihydrite (Fh) and adsorption to pre-formed Fh with two C loadings. The Fh-HA coprecipitated composites have a higher C content and smaller surface area compared to the equivalent adsorbed composites. NanoSIMS shows there is a high degree of spatial correlation between Fe and C for both composites, but C distribution is more uniform in the coprecipitated composites. The C 1s NEXAFS reveals a similar C composition between the Fh-HA coprecipitated and adsorbed composites. However composites at high carbon loading are more enriched in aromatic C, likely due to preferential binding of carboxyl functional groups on aromatic rings in the HA. The amount of Cd sorbed is independent of the composite type, either coprecipitated or adsorbed, but is a function of the C loading. Composites with low C loading show Cd sorption that is almost identical to pure Fh, while composites with high C loading show Cd sorption that is intermediate between pure Fh and pure HA, with sorption significantly enhanced over pure Fh at pH < 6.5. A bidentate edge-sharing binding was identified for Cd on pure Fh and Cd-carboxyl binding on pure HA. These findings have significant implications not only for the sequestration of Cd in contaminated environments but also the coupled biogeochemical cycling of Cd, Fe and C in the critical zone.
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Affiliation(s)
- Huihui Du
- State Key Laboratory of Agricultural Microbiology, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, PR China; Hubei Key Laboratory of Soil Environment and Pollution Remediation, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China; College of Resources and Environment, Hunan Agricultural University, Changsha, 410128, PR China
| | - Caroline L Peacock
- University of Leeds, School of Earth and Environment, Leeds, LS2 9JT, UK.
| | - Wenli Chen
- State Key Laboratory of Agricultural Microbiology, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, PR China
| | - Qiaoyun Huang
- State Key Laboratory of Agricultural Microbiology, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, PR China; Hubei Key Laboratory of Soil Environment and Pollution Remediation, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China.
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13
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Yang R, Li Z, Huang B, Luo N, Huang M, Wen J, Zhang Q, Zhai X, Zeng G. Effects of Fe(III)-fulvic acid on Cu removal via adsorption versus coprecipitation. CHEMOSPHERE 2018; 197:291-298. [PMID: 29353679 DOI: 10.1016/j.chemosphere.2018.01.042] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 11/17/2017] [Accepted: 01/11/2018] [Indexed: 05/27/2023]
Abstract
This study compared the sorption and extractability of Cu following adsorption (SOR) and coprecipitation(CPT). The effect of solution pH, Fe: organic carbon (OC) ratios and fulvic acid (FA) on the combined removal of Cu was investigated in the batch tests using Fe(III) precipitates as a sorbent. Transmission electron microscope (TEM) images demonstrated that the coexisting FA reduced the particle size of ferrihydrites as expected. Generally, more Cu was eliminated in coprecipitation compared with adsorption and the dissolved Cu left in solutions decreased as the pH increased, most of dissolved Cu was trapped at pH 6 and above. Meanwhile, the inhibition or promotion of Cu removal really depended on the different Fe: OC ratios. The addition of FA led to a further decrease of Cu concentrations in CPT systems with Fe/OC ratio of 1:3, however, Cu removal was hindered in the presence of FA in SOR systems. In the case of extraction experiments, the addition of l-malic acid (MA), oxalic acid (OA) and citric acid (CA) resulted in lower extractability of coprecipitated Cu than adsorption samples. The gaps in extractions were seemed to be a consequence of tight Cu binding in CPT products, and the more feasible desorption of Cu from the surface of SOR samples. Based on the results of Cu adsorption and coprecipitation, coprecipitation of Cu with ferrihydrites was the more effective Cu sequestration mechanism in the removal of Cu. These results are helpful to understand the complicated interactions among Fe(III), FA and Cu (II) in the natural environment.
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Affiliation(s)
- Ren Yang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, PR China
| | - Zhongwu Li
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, PR China.
| | - Bin Huang
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Guangdong Institute of Eco-environment Science &Technology, Guangzhou, 510650, PR China
| | - Ninglin Luo
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, PR China
| | - Mei Huang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, PR China
| | - Jiajun Wen
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, PR China
| | - Qiu Zhang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, PR China
| | - Xiuqing Zhai
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, PR China
| | - Guangming Zeng
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, PR China
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14
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Consani S, Carbone C, Salviulo G, Zorzi F, Dinelli E, Botter R, Nodari L, Badocco D, Lucchetti G. Effect of temperature on the release and remobilization of ecotoxic elements in AMD colloidal precipitates: the example of the Libiola copper mine, Liguria, (Italy). ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2016; 23:12900-12914. [PMID: 26988363 DOI: 10.1007/s11356-016-6406-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 03/01/2016] [Indexed: 06/05/2023]
Abstract
Due to their characteristics, colloidal particles are able to control the dispersion of many organic and inorganic pollutants in soils and streams. Colloidal precipitates generated by acid mine drainage (AMD) process are usually amorphous or nanocrystalline materials, and their stability plays a crucial role in controlling the fate of metals released by sulphide oxydation. This paper describes a study of elements release (Fe, Al, Mn, Cd, Co, Cr, Cu, Ni, S, Zn) due to desorption or destabilization of three different colloidal precipitates, two ochreous and a greenish-blue precipitate, sampled at the Libiola mine site (northwest Italy). The samples were heated at high temperature in order to verify this treatment as inertization process. At room temperature, the most easily extracted element was S (with released percentages from 8.39 to 29.17 %), but considerable amounts of Cu, Zn and Mn (up to 16.6, 610.6 and 595.6 mg/kg, respectively) were also observed in the leachates for greenish-blue precipitates. The highest release of elements (S > Cu, Zn, Mn, Cd > Co, Ni > Al, Fe, Cr), with minor differences depending on the mineralogical composition of the samples, was observed for heat-treated samples obtained through moderate heating and mainly formed by anhydrous phases. Samples treated at high temperature had the lowest release, with only Cu showing a significant concentration in the leachate of greenish-blue precipitates. The results showed that dissolution/desorption is limited from ochreous natural colloidal precipitates occurring at the Libiola mine site but also that high amounts of some metals can be remobilized from greenish-blue precipitates. The destabilization of all percipitates through dehydratation-dehydroxylation can further remobilize important amounts of ecotoxic elements. Heat treatment at high temperature could be a definitive, although expensive, way to fix heavy metals in the solid fraction, preventing their dispersion in the surrounding environment.
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Affiliation(s)
- S Consani
- DISTAV, Dipartimento di Scienze della Terra, dell'Ambiente e della Vita, University of Genova, Corso Europa 26, Genova, Italy.
| | - C Carbone
- DISTAV, Dipartimento di Scienze della Terra, dell'Ambiente e della Vita, University of Genova, Corso Europa 26, Genova, Italy
| | - G Salviulo
- Dipartimento di Geoscienze, University of Padova, Via Gradenigo 6, Padova, Italy
| | - F Zorzi
- Dipartimento di Geoscienze, University of Padova, Via Gradenigo 6, Padova, Italy
| | - E Dinelli
- BiGeA, Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Alma Mater Studiorum, University of Bologna, Via Selmi 3, Bologna, Italy
| | - R Botter
- DICAT, Faculty of Engineering, University of Genova, Piazzale. J.F. Kennedy, Pad. D, Genova, Italy
| | - L Nodari
- IENI, Istituto per l'Energetica e le Interfasi, CNR, Corso Stati Uniti, 4, Padova, Italy
| | - D Badocco
- Dipartimento di Scienze Chimiche, University of Padova, Via Marzolo 1, Padova, Italy
| | - G Lucchetti
- DISTAV, Dipartimento di Scienze della Terra, dell'Ambiente e della Vita, University of Genova, Corso Europa 26, Genova, Italy
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15
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Xu Y, Yang M, Yao T, Xiong H. Isolation, identification and arsenic-resistance of Acidithiobacillus ferrooxidans HX3 producing schwertmannite. J Environ Sci (China) 2014; 26:1463-1470. [PMID: 25079995 DOI: 10.1016/j.jes.2014.05.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2013] [Revised: 11/21/2013] [Accepted: 12/31/2013] [Indexed: 06/03/2023]
Abstract
Schwertmannite, a ubiquitous mineral present in iron oxyhydroxides formed in iron- and sulfate-rich acid media, favors incorporation of some toxic anions in its structure. We reported an iron-oxidizing bacterial strain HX3 from a municipal sludge that facilitates the formation of pure schwertmannite in cultures. Ferrous iron oxidation by the isolated strain HX3 was optimum at an initial pH of 2.0-3.3 and temperature of 28-35°C. Pure schwertmannite was found through bacterial oxidation of ferrous iron at an initial pH2.8 and temperature 28°C. Following 16S rDNA gene sequence analysis the bacterial strain HX3 was identified as Acidithiobacillus ferrooxidans. The arsenic-resistance A. ferrooxidans HX3 showed the potential of environmental application in arsenic removal from the As(III)- and iron-rich acid sulfate waters directly by As(III) adsorption or the formation of schwertmannite in the environment.
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Affiliation(s)
- Yiqun Xu
- School of Environmental Science and Engineering, Yangzhou University, Yangzhou 225127, China..
| | - Ming Yang
- School of Environmental Science and Engineering, Yangzhou University, Yangzhou 225127, China
| | - Ting Yao
- School of Environmental Science and Engineering, Yangzhou University, Yangzhou 225127, China
| | - Huixin Xiong
- School of Environmental Science and Engineering, Yangzhou University, Yangzhou 225127, China..
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16
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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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17
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Zhu J, Gan M, Zhang D, Hu Y, Chai L. The nature of Schwertmannite and Jarosite mediated by two strains of Acidithiobacillus ferrooxidans with different ferrous oxidation ability. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2013; 33:2679-85. [DOI: 10.1016/j.msec.2013.02.026] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2012] [Revised: 12/31/2012] [Accepted: 02/17/2013] [Indexed: 11/25/2022]
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18
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Dou X, Mohan D, Pittman CU. Arsenate adsorption on three types of granular schwertmannite. WATER RESEARCH 2013; 47:2938-48. [PMID: 23566332 DOI: 10.1016/j.watres.2013.01.035] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2012] [Revised: 01/19/2013] [Accepted: 01/23/2013] [Indexed: 05/21/2023]
Abstract
Schwertmannite was synthesized on a 2 m(3)-scale and fabricated to irregular, cylindrical and spherical shape granules using drum granulation, extrusion and spray coating, respectively. The granules were systematically evaluated for As(V) removal from drinking water in terms of both performance and safety. The irregular and cylindrical shape granules (IS and CS) had larger schwertmannite loadings, higher porosity, more abundant pore structure and larger micropore volumes than those with a spherical shape (SS). As(V) adsorption kinetics on IS, CS and SS schwertmannite granules followed a pseudo-second order rate equation and two-stages of intraparticle diffusion. The rate parameters were in an order of IS > CS > SS granules. The faster uptake kinetics of the IS granules was due to their largest pore volume and interparticle porosity. Furthermore, adsorption capacities of 34, 21 and 5 mg/g, for IS, CS and SS granular schwertmannite samples were achieved at an initial As(V) concentration of 20 mg/L and adsorbent dose of 0.5 g/L. IS and CS samples performed much better over a wide pH range versus SS samples. Except for humic acid, PO4(3-) and SiO4(4-) did not inhibit As(V) adsorption on IS and CS granular specimens. SS samples worked poorly even in the absence or presence of co-existing anions. Regeneration was achieved using 0.1 M NaOH. The recycled IS and CS granular specimens can be used for 4 different cycles with no or nominal loss of adsorption capacity. Column experiments were also conducted. The IS, CS and SS granular specimens treated 8100, 4200 and 120 bed volumes (BVs) of contaminated water. No heavy metals leached from the packed granular adsorbent and appeared in the column effluent. Furthermore, the toxicity characteristic leaching procedure (TCLP) showed that the spent IS and CS granules were inert and could safely be disposed of in landfills. In short, irregular-shaped granules (IS) fabricated by drum granulation is a good candidate for arsenic removal from drinking water with a high future application potential.
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Affiliation(s)
- Xiaomin Dou
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, PR China.
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19
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Zermane F, Cheknane B, Basly JP, Bouras O, Baudu M. Influence of humic acids on the adsorption of Basic Yellow 28 dye onto an iron organo–inorgano pillared clay and two Hydrous Ferric Oxides. J Colloid Interface Sci 2013; 395:212-6. [DOI: 10.1016/j.jcis.2012.12.038] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Revised: 12/10/2012] [Accepted: 12/15/2012] [Indexed: 11/16/2022]
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20
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Antelo J, Fiol S, Gondar D, López R, Arce F. Comparison of arsenate, chromate and molybdate binding on schwertmannite: surface adsorption vs anion-exchange. J Colloid Interface Sci 2012; 386:338-43. [PMID: 22901683 DOI: 10.1016/j.jcis.2012.07.008] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Revised: 06/29/2012] [Accepted: 07/03/2012] [Indexed: 11/29/2022]
Abstract
The presence of iron oxides may play an important role in controlling the mobility and availability of contaminants in soils and waters affected by acid mine drainage. The present study describes the uptake of arsenate, chromate and molybdate from solution by synthetic schwertmannite. Batch experiments were performed at different pH values in order to obtain the adsorption isotherms for the three oxyanions. In addition to the formation of surface complexes between the oxyanions and the iron surface reactive groups, it is also expected that anion exchange will occur between sulphate anions from the schwertmannite structure and the oxyanions present in the solid/solution interface. Comparison of the experimental adsorption results for the different oxyanions showed large differences, not only the amount adsorbed, which was much higher for arsenate, but also in the sulphate exchange with the anions in solution. In case of chromate, the main mechanism of adsorption process is the exchange reaction with the sulphate groups present in the schwertmannite. The observed results suggest a different adsorption mechanisms for each of the three oxyanions, with important implications for the mobility of these anions in acid mine drainage systems.
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Affiliation(s)
- Juan Antelo
- Department of Soil Science and Agricultural Chemistry, University of Santiago de Compostela, Santiago de Compostela, Spain.
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21
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Butler BA. Effect of imposed anaerobic conditions on metals release from acid-mine drainage contaminated streambed sediments. WATER RESEARCH 2011; 45:328-336. [PMID: 20709348 DOI: 10.1016/j.watres.2010.07.077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Revised: 07/23/2010] [Accepted: 07/26/2010] [Indexed: 05/29/2023]
Abstract
Remediation of streams influenced by mine-drainage may require removal and burial of metal-containing bed sediments. Burial of aerobic sediments into an anaerobic environment may release metals, such as through reductive dissolution of metal oxyhydroxides. Mining-impacted aerobic streambed sediments collected from North Fork Clear Creek, Colorado were held under anaerobic conditions for four months. Eh, pH, and concentrations of Cd, Cu, Fe, Mn, and Zn (filtered at 1.5 μm, 0.45 μm, and 0.2 μm), sulfate, and dissolved organic carbon (DOC) were monitored in stream water/sediment slurries. Two sediment size fractions were examined (2 mm-63 μm and <63 μm). Sequential extractions evaluated the mineral phase with which metals were associated in the aerobic sediment. Released Cu was re-sequestered within 5 weeks, while Fe and Mn still were present at 16 weeks. Mn concentration was lower than in the initial stream water at and beyond 14 weeks for the smaller sized sediment. Cd was not released from either sediment size fraction. Zn was released at early times, but concentrations never exceeded those present in the initial stream water and all was re-sequestered over time. The greatest concentrations of Cu, Fe, Mn, and Zn were associated with the Fe/Mn reducible fraction. Sulfate and Fe were strongly correlated (r = 0.90), seeming to indicate anaerobic dissolution of iron oxy-hydroxy-sulfate minerals. DOC and sulfate were strongly correlated (r = 0.81), with iron having a moderately strong correlation with DOC (r = 0.71). Overall concentrations of DOC, sulfate, Cu, Fe, and Zn and pH were significantly higher (p < 0.05) in the water overlying the small sized sediment samples, while the concentrations of Mn released from the larger sized sediment samples were greater.
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Affiliation(s)
- Barbara A Butler
- Land Remediation and Pollution Control Division, US EPA Office of Research and Development, National Risk Management Research Laboratory, 26 W. Martin Luther King Drive, Cincinnati, OH 45268, USA.
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22
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Kumpulainen S, von der Kammer F, Hofmann T. Humic acid adsorption and surface charge effects on schwertmannite and goethite in acid sulphate waters. WATER RESEARCH 2008; 42:2051-2060. [PMID: 18221768 DOI: 10.1016/j.watres.2007.12.015] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2007] [Revised: 12/17/2007] [Accepted: 12/18/2007] [Indexed: 05/25/2023]
Abstract
In acid conditions, as in acid mine drainage waters, iron oxide particles are positively charged, attracting negatively charged organic particles present in surrounding natural waters. Schwertmannite (Fe8O8(OH)6SO4) and goethite (alpha-FeOOH) are the most typical iron oxide minerals found in mine effluents. We studied schwertmannite formation in the presence of humic acid. Further, surface charge and adsorption of humic acid on synthetic schwertmannite and goethite surfaces in pH 2-9 and in humic acid concentrations of 0.1-100 mg/L C were examined. Schwertmannite did precipitate despite the presence of humic acid, although it contained more sulphate and had higher specific surface area than ordinary schwertmannite. Specific surface area weighted results showed that schwertmannite and goethite had similar humic acid adsorption capacities. Sulphate was released from schwertmannite surfaces with increasing pH, resulting in an increase in specific surface area. Presence of sulphate in solution decreased the surface charge of schwertmannite and goethite similarly, causing coagulation. In acid conditions (pH 2-3.5), according to the zeta potential, schwertmannite is expected to coagulate even in the presence of high concentrations of humic acid (< or = 100 mg/L C). However, at high humic acid concentrations (10-100 mg/L C) with moderate acid conditions (pH>3.5), both schwertmannite and goethite surfaces are strongly negatively charged (zeta potential < -30 mV) thus posing a risk for colloid stabilization and colloidal transport.
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