1
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Nano-alumina wrapped carbon microspheres for ultrahigh elimination of pentavalent arsenic and fluoride from potable water. J IND ENG CHEM 2022. [DOI: 10.1016/j.jiec.2022.10.028] [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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2
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Yang Z, Zhang N, Sun B, Su S, Wang Y, Zhang Y, Wu C, Zeng X. Contradictory tendency of As(V) releasing from Fe-As complexes: Influence of organic and inorganic anions. CHEMOSPHERE 2022; 286:131469. [PMID: 34340118 DOI: 10.1016/j.chemosphere.2021.131469] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 07/02/2021] [Accepted: 07/06/2021] [Indexed: 06/13/2023]
Abstract
The strong ability of ferrihydrite and its aged minerals for fixing arsenate is a key factor in remediating arsenate-polluted environments. It is therefore crucial to clarify the stability of Fe-As complexes and the release conditions for As(V). The As(V) release amount was evaluated and compared in the presence of six representative anions, namely, phosphate, silicate, sulfate, inositol hexaphosphate, citrate, and oxalate. It was found that the As(V) release amount changed with the aging time of ferrihydrite and that this tendency generally followed two rules. These are, longer aging time leads to lower As(V) release (Rule 1), and longer aging time leads to higher As(V) release (Rule 2). Whether Rule 1 or Rule 2 dominated As release depended on the number of surface groups, size of competing anions, and contribution of As(V) re-adsorption. Characterization results using X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) provided evidence for the predicted mechanisms of As(V) release under various circumstances. In this work, it was demonstrated that when inorganic anions such as sulfate and silicate are present, ferrihydrite with longer aging time led to decreased As(V) release. When organic anions are present, ferrihydrite with less aging time results in reduced As(V) leaching. For anions such as phosphate, the As(V) release amount in relation to the ferrihydrite aging time depends on the concentration of phosphate ions. Nevertheless, the ligand concentration and As(V) loading rate on ferrihydrite should be simultaneously considered for the rule governing As(V) releasing.
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Affiliation(s)
- Zhonglan Yang
- Institute of Agricultural Environment and Sustainable Development, Chinese Academy of Agriculture Sciences, Beijing, 100081, China; College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, China
| | - Nan Zhang
- Institute of Agricultural Environment and Sustainable Development, Chinese Academy of Agriculture Sciences, Beijing, 100081, China
| | - Benhua Sun
- College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, China
| | - Shiming Su
- Institute of Agricultural Environment and Sustainable Development, Chinese Academy of Agriculture Sciences, Beijing, 100081, China
| | - Yanan Wang
- Institute of Agricultural Environment and Sustainable Development, Chinese Academy of Agriculture Sciences, Beijing, 100081, China
| | - Yang Zhang
- Institute of Agricultural Environment and Sustainable Development, Chinese Academy of Agriculture Sciences, Beijing, 100081, China
| | - Cuixia Wu
- Institute of Agricultural Environment and Sustainable Development, Chinese Academy of Agriculture Sciences, Beijing, 100081, China
| | - Xibai Zeng
- Institute of Agricultural Environment and Sustainable Development, Chinese Academy of Agriculture Sciences, Beijing, 100081, China.
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3
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Layered Double Hydroxide Sorbents for Removal of Selenium from Power Plant Wastewaters. CHEMENGINEERING 2019. [DOI: 10.3390/chemengineering3010020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Selenium is an essential trace element but is increasingly becoming a contaminant of concern in the electric power industry due to the challenges of removing solubilized selenate anions, particularly in the presence of sulfate. In this work, we evaluate granulated layered double hydroxide (LDH) materials as sorbents for selenium removal from wastewaters obtained from a natural gas power plant with the aim to elucidate the effect of competing ions on the sorption capacities for selenium removal. We first present jar test data, followed by small-scale column testing in 0.43 inch (1.1 cm) and 2 inch (5.08 cm) diameter testbed columns for the treatment of as-obtained cooling tower blowdown waters and plant wastewaters. Finally, we present field results from a pilot-scale study evaluating the LDH media for treatment of cooling tower blowdown water. We find that despite the high levels of total dissolved solids and competing sulfate ions, the selenium oxoanions and other regulated metals such as chromium and arsenic are successfully removed using LDH media without needing any pre-treatment or pH adjustment of the wastewater.
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4
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Huang B, Guo Z, Xiao X, Zeng P, Peng C. Changes in chemical fractions and ecological risk prediction of heavy metals in estuarine sediments of Chunfeng Lake estuary, China. MARINE POLLUTION BULLETIN 2019; 138:575-583. [PMID: 30660308 DOI: 10.1016/j.marpolbul.2018.12.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 12/10/2018] [Accepted: 12/11/2018] [Indexed: 06/09/2023]
Abstract
The changes of available forms of heavy metals would affect their corresponding ecological risks in sediments. The distribution of chemical fractions of heavy metals in sediment profiles from Chunfeng Lake estuary was investigated and then a prediction model for potential ecological risk index (PMRI) was proposed to forecast the changes of ecological risks caused by the aging process of metals in sediments. The results show that the estuarine sediments were polluted by As and Cd. The proportions of available metals were generally decreased with depth, while those of the residual forms showed an opposite trend. The aging rates of Cd and As were found to be 0.21 and 0.12%/year, respectively. The PMRI model showed that the total ecological risk of metals in sediments decreased from moderate to low risk level (<150) after 25 years, while cadmium would need 47 years in contrast to the 15 years for As.
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Affiliation(s)
- Bo Huang
- Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, People's Republic of China; Yueyang Environmental Monitoring Centre, Yueyang 414000, People's Republic of China
| | - Zhaohui Guo
- Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, People's Republic of China
| | - Xiyuan Xiao
- Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, People's Republic of China
| | - Peng Zeng
- Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, People's Republic of China
| | - Chi Peng
- Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, People's Republic of China.
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Zhang P, Zhang N, Li Z, Yean S, Li H, Shipley HJ, Kan AT, Chen W, Tomson MB. Identification of a new high-molecular-weight Fe-citrate species at low citrate-to-Fe molar ratios: Impact on arsenic removal with ferric hydroxide. CHEMOSPHERE 2018; 212:50-55. [PMID: 30138855 DOI: 10.1016/j.chemosphere.2018.08.066] [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: 05/22/2018] [Revised: 08/03/2018] [Accepted: 08/14/2018] [Indexed: 06/08/2023]
Abstract
Ferric hydroxide precipitation and flocculation is the most commonly used method for the removal of arsenic in water treatment. However, citrate often interrupts the precipitation of ferric hydroxides and thus affects arsenic removal. To date, the mechanisms controlling the effects of citrate on arsenic removal with ferric hydroxide flocculation and precipitation at very low citrate-to-Fe molar ratios are not well understood. Herein, we report a new mechanism by which citrate inhibits arsenic removal using ferric hydroxide. At a substoichiometric citrate-to-Fe molar ratio of 0.28, citrate forms a high-molecular-weight Fe-citrate (Fe4Cit) species. The optimized structure of the Fe4Cit species was obtained by the density functional theory calculation. To the best of our knowledge, this study is the first to report the formation and to identify the structure of dominant Fe-citrate species at a very low citrate-to-Fe molar ratio.
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Affiliation(s)
- Ping Zhang
- Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau, PR China.
| | - Nan Zhang
- Department of Civil and Environmental Engineering, Rice University, Houston, TX, 77005, USA
| | - Zhejun Li
- Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau, PR China
| | - Sujin Yean
- Department of Civil and Environmental Engineering, Rice University, Houston, TX, 77005, USA
| | - Hualin Li
- Department of Civil and Environmental Engineering, Rice University, Houston, TX, 77005, USA
| | - Heather J Shipley
- Department of Civil and Environmental Engineering, University of Texas at San Antonio, San Antonio, TX, 78249, USA
| | - Amy T Kan
- Department of Civil and Environmental Engineering, Rice University, Houston, TX, 77005, USA; Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, Rice University, Houston, TX, 77005, USA
| | - Wei Chen
- College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, PR China.
| | - Mason B Tomson
- Department of Civil and Environmental Engineering, Rice University, Houston, TX, 77005, USA; Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, Rice University, Houston, TX, 77005, USA
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6
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Hu S, Lu Y, Peng L, Wang P, Zhu M, Dohnalkova AC, Chen H, Lin Z, Dang Z, Shi Z. Coupled Kinetics of Ferrihydrite Transformation and As(V) Sequestration under the Effect of Humic Acids: A Mechanistic and Quantitative Study. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:11632-11641. [PMID: 30230819 DOI: 10.1021/acs.est.8b03492] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
In natural environments, kinetics of As(V) sequestration/release is usually coupled with dynamic Fe mineral transformation, which is further influenced by the presence of natural organic matter (NOM). Previous work mainly focused on the interactions between As(V) and Fe minerals. However, there is a lack of both mechanistic and quantitative understanding on the coupled kinetic processes in the As(V)-Fe mineral-NOM system. In this study, we investigated the effect of humic acids (HA) on the coupled kinetics of ferrihydrite transformation into hematite/goethite and sequestration of As(V) on Fe minerals. Time-resolved As(V) and HA interactions with Fe minerals during the kinetic processes were studied using aberration-corrected scanning transmission electron microscopy, chemical extractions, stirred-flow kinetic experiments, and X-ray absorption spectroscopy. Based on the experimental results, we developed a mechanistic kinetics model for As(V) fate during Fe mineral transformation. Our results demonstrated that the rates of As(V) speciation changes within Fe minerals were coupled with ferrihydrite transformation rates, and the overall reactions were slowed down by the presence of HA that sorbed on Fe minerals. Our kinetics model is able to account for variations of Fe mineral compositions, solution chemistry, and As(V) speciation, which has significant environmental implications for predicting As(V) behavior in the environment.
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Affiliation(s)
- Shiwen Hu
- The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, School of Environment and Energy , South China University of Technology , Guangzhou , Guangdong 510006 , People's Republic of China
| | - Yang Lu
- The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, School of Environment and Energy , South China University of Technology , Guangzhou , Guangdong 510006 , People's Republic of China
| | - Lanfang Peng
- The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, School of Environment and Energy , South China University of Technology , Guangzhou , Guangdong 510006 , People's Republic of China
| | - Pei Wang
- The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, School of Environment and Energy , South China University of Technology , Guangzhou , Guangdong 510006 , People's Republic of China
| | - Mengqiang Zhu
- Department of Ecosystem Science and Management , University of Wyoming , Laramie , Wyoming 82071 , United States
| | - Alice C Dohnalkova
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory , Richland , Washington 99354 , United States
| | - Hong Chen
- SLAC National Accelerator Laboratory , Stanford University , Menlo Park , California 94025 , United States
| | - Zhang Lin
- The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, School of Environment and Energy , South China University of Technology , Guangzhou , Guangdong 510006 , People's Republic of China
| | - Zhi Dang
- The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, School of Environment and Energy , South China University of Technology , Guangzhou , Guangdong 510006 , People's Republic of China
| | - Zhenqing Shi
- The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, School of Environment and Energy , South China University of Technology , Guangzhou , Guangdong 510006 , People's Republic of China
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Rasool A, Farooqi A, Xiao T, Ali W, Noor S, Abiola O, Ali S, Nasim W. A review of global outlook on fluoride contamination in groundwater with prominence on the Pakistan current situation. ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 2018; 40:1265-1281. [PMID: 29260447 DOI: 10.1007/s10653-017-0054-z] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 12/11/2017] [Indexed: 05/06/2023]
Abstract
Several million people are exposed to fluoride (F-) via drinking water in the world. Current review emphasized the elevated level of fluoride concentrations in the groundwater and associated potential health risk globally with a special focus on Pakistan. Millions of people are deeply dependent on groundwater from different countries of the world encompassing with an elevated level of fluoride. The latest estimates suggest that around 200 million people, from among 25 nations the world over, are under the dreadful fate of fluorosis. India and China, the two most populous countries of the world, are the worst affected. In Pakistan, fluoride data of 29 major cities are reviewed and 34% of the cities show fluoride levels with a mean value greater than 1.5 mg/L where Lahore, Quetta and Tehsil Mailsi are having the maximum values of 23.60, 24.48, > 5.5 mg/L, respectively. In recent years, however, other countries have minimized, even eliminated its use due to health issues. High concentration of fluoride for extended time period causes adverse effects of health such as skin lesions, discoloration, cardiovascular disorders, dental fluorosis and crippling skeletal fluorosis. This review deliberates comprehensive strategy of drinking water quality in the global scenario of fluoride contamination, especially in Pakistan with prominence on major pollutants, mitigation technologies, sources of pollution and ensuing health problems. Considering these verities, health authorities urgently need to establish alternative means of water decontamination in order to prevent associated health problems.
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Affiliation(s)
- Atta Rasool
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Abida Farooqi
- Environmental Hydro-Geochemistry Laboratory, Department of Environmental Sciences, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, 45320, Pakistan.
| | - Tangfu Xiao
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China.
- The Key Laboratory of Water Safety and Protection in the Pearl River Delta, Ministry of Education, School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 510006, China.
| | - Waqar Ali
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Sifat Noor
- Environmental Hydro-Geochemistry Laboratory, Department of Environmental Sciences, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, 45320, Pakistan
| | - Oyebamiji Abiola
- University of Chinese Academy of Sciences, Beijing, 100049, China
- State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Salar Ali
- Key Laboratory of Watershed Geographic Sciences, Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, Nanjing, 210008, China
| | - Wajid Nasim
- Department of Environmental Sciences, COMSATS Institute of Information Technology, Vehari, 61100, Pakistan
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8
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Park I, Tabelin CB, Seno K, Jeon S, Ito M, Hiroyoshi N. Simultaneous suppression of acid mine drainage formation and arsenic release by Carrier-microencapsulation using aluminum-catecholate complexes. CHEMOSPHERE 2018; 205:414-425. [PMID: 29704849 DOI: 10.1016/j.chemosphere.2018.04.088] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 04/11/2018] [Accepted: 04/16/2018] [Indexed: 06/08/2023]
Abstract
Pyrite (FeS2), the most common sulfide mineral in nature, plays an important role in the formation of acid mine drainage (AMD), one of the most serious environmental problems after the closure of mines and mineral processing operations. Likewise, arsenopyrite (FeAsS) is an important sulfide mineral because its dissolution releases toxic arsenic (As) into the environment. To mitigate the serious environmental problems caused by pyrite and arsenopyrite, this study investigated carrier-microencapsulation (CME) using Al-catecholate complexes, a technique that selectively forms protective coatings on the surfaces of sulfide minerals, by electrochemical techniques and batch leaching experiments coupled with surface sensitive characterization techniques. Cyclic voltammetry (CV) of Al-catecholate complexes (mono-, bis-, tris-catecholate) suggest that these three species could be oxidatively decomposed in this order: [Al(cat)3]3-→[Al(cat)2]-→[Al(cat)]+→Al3+, and these reactions were irreversible. Among these three species, [Al(cat)]+ was the most effective in suppressing pyrite and arsenopyrite oxidations because it requires less steps for complete decomposition than the other two complexes. Analyses of CME treated minerals by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) indicated that they were covered with Al-oxyhydroxide (γ-AlO(OH)), which became more extensive at higher [Al(cat)]+ concentrations. In addition, this coating was stable even at relatively high applied potentials that simulated surface oxidizing conditions. Based on these results, a detailed mechanism of Al-based CME is proposed: (1) adsorption of [Al(cat)]+ on the surface of mineral, (2) oxidative decomposition of [Al(cat)]+ and release of "free" Al3+, and (3) precipitation and formation of Al-oxyhydroxide coating.
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Affiliation(s)
- Ilhwan Park
- Laboratory of Mineral Processing and Resources Recycling, Division of Sustainable Resources Engineering, Graduate School of Engineering, Hokkaido University, Japan.
| | - Carlito Baltazar Tabelin
- Laboratory of Mineral Processing and Resources Recycling, Division of Sustainable Resources Engineering, Faculty of Engineering, Hokkaido University, Japan
| | - Kensuke Seno
- Laboratory of Mineral Processing and Resources Recycling, Division of Sustainable Resources Engineering, Graduate School of Engineering, Hokkaido University, Japan
| | - Sanghee Jeon
- Laboratory of Mineral Processing and Resources Recycling, Division of Sustainable Resources Engineering, Graduate School of Engineering, Hokkaido University, Japan
| | - Mayumi Ito
- Laboratory of Mineral Processing and Resources Recycling, Division of Sustainable Resources Engineering, Faculty of Engineering, Hokkaido University, Japan
| | - Naoki Hiroyoshi
- Laboratory of Mineral Processing and Resources Recycling, Division of Sustainable Resources Engineering, Faculty of Engineering, Hokkaido University, Japan
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Zhang X, Jia S, Song J, Wu S, Han X. Highly Efficient Utilization of Soluble Fe in the Removal of Arsenic during Oxidative Flocculation of Fe(II). BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2018. [DOI: 10.1246/bcsj.20180014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Xuezhi Zhang
- School of Chemical Engineering and Technology, Tianjin University, NO.135 Yaguan Road, Jinnan District, Tianjin 300350, P. R. China
| | - Shaoyi Jia
- School of Chemical Engineering and Technology, Tianjin University, NO.135 Yaguan Road, Jinnan District, Tianjin 300350, P. R. China
| | - Jia Song
- School of Chemical Engineering and Technology, Tianjin University, NO.135 Yaguan Road, Jinnan District, Tianjin 300350, P. R. China
| | - Songhai Wu
- School of Chemical Engineering and Technology, Tianjin University, NO.135 Yaguan Road, Jinnan District, Tianjin 300350, P. R. China
| | - Xu Han
- School of Environmental Science and Engineering, Tianjin University, NO.135 Yaguan Road, Jinnan District, Tianjin 300350, P. R. China
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Vasques ICF, de Mello JWV, Veloso RW, Ferreira VDP, Abrahão WAP. Arsenite removal from contaminated water by precipitation of aluminum, ferrous and ferric (hydr)oxides. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:12967-12980. [PMID: 29478170 DOI: 10.1007/s11356-018-1458-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Accepted: 02/01/2018] [Indexed: 06/08/2023]
Abstract
Several methods to remove arsenic from water have been considered, including co-precipitation with Fe and Al (hydr)oxides. Such compounds are considered very effective to remove As from contaminated water due to strong bindings between them. Three Fe:Al molar ratios (100:0, 80:20, and 60:40) were used to synthesize aluminum, ferrous, and ferric (hydr)oxides by precipitation in water highly contaminated with arsenite (50 and 500 mg L-1). The method was very efficient for all treatments (> 93%) at the beginning of the incubation period, excepted the one with 60:40 Fe(II):Al molar ratio at the higher As concentration (500 mg L-1) in which gibbsite was identified in precipitated phases. In spite of the high efficiency, however, the threshold for drinking water was not attained, mainly to the higher As concentration, even 84 days after precipitation. At this high concentration of arsenite, even the required threshold for effluent discharge was not attained in some treatments. The sludge resulting from treatments with higher As concentration were considered hazardous according to results from leaching test and corroborated by BCR extractions. Arsenic associated with Al and adsorbed phases were also assessed by extractions with NH4F and KH2PO4, respectively. In general, the presence of Al increased the efficiency as well as the stability of the sludge resulting from Fe (II) treatments, but did not affect Fe (III) treatments, which were more efficient for As removal.
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Affiliation(s)
- Isabela C F Vasques
- Soil Department, Universidade Federal de Viçosa, PH Rolfs Avenue, Viçosa, MG, Brazil.
| | - Jaime W V de Mello
- Soil Department, Universidade Federal de Viçosa, PH Rolfs Avenue, Viçosa, MG, Brazil
- National Institute of Science and Technology, INCT Acqua, Belo Horizonte, Brazil
| | | | - Vanessa de P Ferreira
- Soil Department, Universidade Federal de Viçosa, PH Rolfs Avenue, Viçosa, MG, Brazil
| | - Walter A P Abrahão
- Soil Department, Universidade Federal de Viçosa, PH Rolfs Avenue, Viçosa, MG, Brazil
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Freitas ETF, Stroppa DG, Montoro LA, de Mello JWV, Gasparon M, Ciminelli VST. Arsenic entrapment by nanocrystals of Al-magnetite: The role of Al in crystal growth and As retention. CHEMOSPHERE 2016; 158:91-99. [PMID: 27258899 DOI: 10.1016/j.chemosphere.2016.05.044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 05/05/2016] [Accepted: 05/13/2016] [Indexed: 06/05/2023]
Abstract
The nature of As-Al-Fe co-precipitates aged for 120 days are investigated in detail by High Resolution Transmission Electron Microscopy (HRTEM), Scanning TEM (STEM), electron diffraction, Energy Dispersive X-Ray Spectroscopy (EDS), Electron Energy-Loss Spectroscopy (EELS), and Energy Filtered Transmission Electron Microscopy (EFTEM). The Al present in magnetite is shown to favour As incorporation (up to 1.10 wt%) relative to Al-free magnetite and Al-goethite, but As uptake by Al-magnetite decreases with increasing Al substitution (3.53-11.37 mol% Al). Arsenic-bearing magnetite and goethite mesocrystals (MCs) are formed by oriented aggregation (OA) of primary nanoparticles (NPs). Well-crystalline magnetite likely formed by Otswald ripening was predominant in the Al-free system. The As content in Al-goethite MCs (having approximately 13% substituted Al) was close to the EDS detection limit (0.1 wt% As), but was below detection in Al-goethites with 23.00-32.19 mol% Al. Our results show for the first time the capacity of Al-magnetite to incorporate more As than Al-free magnetite, and the role of Al in favouring OA-based crystal growth under the experimental conditions, and therefore As retention in the formed MCs. The proposed mechanism of As incorporation involves adsorption of As onto the newly formed NPs. Arsenic is then trapped in the MCs as they grow by self-assembly OA upon attachment of the NPs. We conclude that Al may diffuse to the crystal faces with high surface energy to reduce the total energy of the system during the attachment events, thus favouring the oriented aggregation.
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Affiliation(s)
- Erico T F Freitas
- Universidade Federal de Minas Gerais, Center of Microscopy, Belo Horizonte 31270901, Brazil; The University of Queensland, School of Earth Sciences, St Lucia 4072, Australia; National Institute of Science and Technology on Minerals Resources, Water and Biodiversity, INCT-Acqua, Brazil.
| | - Daniel G Stroppa
- International Iberian Nanotechnology Laboratory, Braga 4715330, Portugal.
| | - Luciano A Montoro
- Universidade Federal de Minas Gerais, Department of Chemistry, Belo Horizonte 31270901, Brazil; National Institute of Science and Technology on Minerals Resources, Water and Biodiversity, INCT-Acqua, Brazil.
| | - Jaime W V de Mello
- Universidade Federal de Viçosa, Department of Soils, Viçosa 36570900, Brazil; National Institute of Science and Technology on Minerals Resources, Water and Biodiversity, INCT-Acqua, Brazil.
| | - Massimo Gasparon
- The University of Queensland, School of Earth Sciences, St Lucia 4072, Australia; National Institute of Science and Technology on Minerals Resources, Water and Biodiversity, INCT-Acqua, Brazil.
| | - Virginia S T Ciminelli
- Universidade Federal de Minas Gerais, Department of Metallurgical Engineering, Belo Horizonte 31270901, Brazil; National Institute of Science and Technology on Minerals Resources, Water and Biodiversity, INCT-Acqua, Brazil.
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12
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Sommella A, Caporale AG, Denecke MA, Mangold S, Pigna M, Santoro A, Terzano R, Violante A. Nature and reactivity of layered double hydroxides formed by coprecipitating Mg, Al and As(V): Effect of arsenic concentration, pH, and aging. JOURNAL OF HAZARDOUS MATERIALS 2015; 300:504-512. [PMID: 26241870 DOI: 10.1016/j.jhazmat.2015.07.046] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 07/15/2015] [Accepted: 07/17/2015] [Indexed: 06/04/2023]
Abstract
Arsenic (As) co-precipitation is one of the major processes controlling As solubility in soils and waters. When As is co-precipitated with Al and Mg, the possible formation of layered double hydroxides (LDHs) and other nanocomposites can stabilize As in their structures thus making this toxic element less available. We investigated the nature and reactivity of Mg-Al-arsenate [As(V)] co-precipitated LDHs formed in solution affected by As concentration, pH, and aging. At the beginning of the co-precipitation process, poorly crystalline LDH and non-crystalline Al(Mg)-oxides form. Prolonged aging of the samples promotes crystallization of LDHs, evidenced by an increase in As K XANES intensities and XRD peak intensities. During aging Al- and/or Mg-oxides are likely transformed by dissolution/re-precipitation processes into more crystalline but still defective LDHs. Surface area, chemical composition, reactivity of the precipitates, and anion exchange properties of As(V) in the co-precipitates are influenced by pH, aging, and As concentration. This study demonstrates that (i) As(V) retards or inhibits the formation and transformation of LDHs and (ii) more As(V) is removed from solution if co-precipitated with Mg and Al than by sorption onto well crystallized LDHs.
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Affiliation(s)
- Alessia Sommella
- Dipartimento di Agraria, Università di Napoli Federico II, Via Università 100, 80055 Portici (Napoli), Italy
| | - Antonio G Caporale
- Dipartimento di Agraria, Università di Napoli Federico II, Via Università 100, 80055 Portici (Napoli), Italy
| | - Melissa A Denecke
- Dalton Nuclear Institute, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - Stefan Mangold
- Karlsruhe Institute of Technology, ANKA Synchrotron Facility, Hermann-von-Helmholtz-Platz 1, Karlsruhe, Germany
| | - Massimo Pigna
- Dipartimento di Agraria, Università di Napoli Federico II, Via Università 100, 80055 Portici (Napoli), Italy
| | - Anna Santoro
- Bangor University, School of Chemistry, Bangor LL 57 2UW, United Kingdom
| | - Roberto Terzano
- Department of Soil, Plant and Food Sciences, University of Bari "Aldo Moro", Via G. Amendola 165/A, 70126 Bari, Italy
| | - Antonio Violante
- Dipartimento di Agraria, Università di Napoli Federico II, Via Università 100, 80055 Portici (Napoli), Italy.
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13
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Freitas ETF, Montoro LA, Gasparon M, Ciminelli VST. Natural attenuation of arsenic in the environment by immobilization in nanostructured hematite. CHEMOSPHERE 2015; 138:340-347. [PMID: 26126189 DOI: 10.1016/j.chemosphere.2015.05.101] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 05/13/2015] [Accepted: 05/27/2015] [Indexed: 06/04/2023]
Abstract
Iron (hydr)oxides are known to play a major role in arsenic fixation in the environment. The mechanisms for long-term fixation into their crystal structure, however, remain poorly understood, especially arsenic partitioning behavior during transformation from amorphous to crystalline phases under natural conditions. In this study, these mechanisms are investigated in Fe-Al-oxisols exposed over a period of 10 years to a sulfide concentrate in tailings impoundments. The spatial resolution necessary to investigate the markedly heterogeneous nanoscale phases found in the oxisols was achieved by combining three different, high resolution electron microscopy techniques - Nano-Beam Electron Diffraction (NBD), Electron Energy-Loss Spectroscopy (EELS), and High Resolution Transmission Electron Microscopy (HRTEM). Arsenic (1.6±0.5 wt.%) was unambiguously and precisely identified in mesocrystals of Al-hematite with an As/Fe atomic ratio of 0.026±0.006. The increase in the c-axis (c=1.379±0.009 nm) compared to standard hematite (c=1.372 nm) is consistent with the presence of arsenic in the Al-hematite structure. The As-bearing Al-hematite is interpreted as a secondary phase formed from oxyhydroxides, such as ferrihydrite, during the long-term exposure to the sulfide tailings. The proposed mechanism of arsenic fixation in the Al-hematite structure involves adsorption onto Al-ferrihydrite nanoparticles, followed by Al-ferrihydrite aggregation by self-assembly oriented attachment and coalescence that ultimately produces Al-hematite mesocrystals. Our results illustrate for the first time the process of formation of stable arsenic bearing Al-hematite for the long-term immobilization of arsenic in environmental samples.
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Affiliation(s)
- Erico T F Freitas
- Centre of Microscopy, Universidade Federal de Minas Gerais, Belo Horizonte 31270901, Brazil; National Institute of Science and Technology on Minerals Resources, Water and Biodiversity, INCT-Acqua, Brazil.
| | - Luciano A Montoro
- Department of Chemistry, Universidade Federal de Minas Gerais, Belo Horizonte 31270901, Brazil; National Institute of Science and Technology on Minerals Resources, Water and Biodiversity, INCT-Acqua, Brazil.
| | - Massimo Gasparon
- School of Earth Sciences, The University of Queensland, Brisbane 4072, Australia; National Institute of Science and Technology on Minerals Resources, Water and Biodiversity, INCT-Acqua, Brazil.
| | - Virginia S T Ciminelli
- Department of Metallurgical Engineering, Universidade Federal de Minas Gerais, Belo Horizonte 31270901, Brazil; National Institute of Science and Technology on Minerals Resources, Water and Biodiversity, INCT-Acqua, Brazil.
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14
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Tong M, Yuan S, Zhang P, Liao P, Alshawabkeh AN, Xie X, Wang Y. Electrochemically induced oxidative precipitation of Fe(II) for As(III) oxidation and removal in synthetic groundwater. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:5145-53. [PMID: 24708303 PMCID: PMC6321744 DOI: 10.1021/es500409m] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Mobilization of Arsenic in groundwater is primarily induced by reductive dissolution of As-rich Fe(III) oxyhydroxides under anoxic conditions. Creating a well-controlled artificial environment that favors oxidative precipitation of Fe(II) and subsequent oxidation and uptake of aqueous As can serve as a remediation strategy. We reported a proof of concept study of a novel iron-based dual anode system for As(III) oxidation and removal in synthetic groundwater. An iron anode was used to produce Fe(II) under iron-deficient conditions, and another inert anode was used to generate O2 for oxidative precipitation of Fe(II). For 30 min's treatment, 6.67 μM (500 μg/L) of As(III) was completely oxidized and removed from the solution during the oxidative precipitation process when a total current of 60 mA was equally partitioned between the two anodes. The current on the inert anode determined the rate of O2 generation and was linearly related to the rates of Fe(II) oxidation and of As oxidation and removal, suggesting that the process could be manipulated electrochemically. The composition of Fe precipitates transformed from carbonate green rust to amorphous iron oxyhydroxide as the inert anode current increased. A conceptual model was proposed for the in situ application of the electrochemically induced oxidative precipitation process for As(III) remediation.
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Affiliation(s)
- Man Tong
- State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, P. R. China
| | - Songhu Yuan
- State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, P. R. China
| | - Peng Zhang
- State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, P. R. China
| | - Peng Liao
- State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, P. R. China
| | - Akram N. Alshawabkeh
- Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Xianjun Xie
- State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, P. R. China
| | - Yanxin Wang
- State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, P. R. China
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15
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Wu K, Liu T, Ma C, Chang B, Chen R, Wang X. The role of Mn oxide doping in phosphate removal by Al-based bimetal oxides: adsorption behaviors and mechanisms. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2014; 21:620-630. [PMID: 23818076 DOI: 10.1007/s11356-013-1937-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 06/12/2013] [Indexed: 06/02/2023]
Abstract
This study investigated the behaviors and mechanisms of phosphate adsorbed onto manganese (Mn) oxide-doped aluminum (Al) oxide (MODAO). The isotherm results demonstrated that the maximum amount of phosphorus (P) adsorbed onto MODAO was 59.8 mg/g at T = 298 K (pH 6.0). This value was nearly twice the amount of singular AlOOH and could increase with rising temperatures. The kinetic results illustrated that most of the P was adsorbed onto MODAO within 5 h, which was shorter than the equilibrium time of phosphate adsorption onto AlOOH. The Elovich model effectively described the adsorption kinetic data of MODAO because of its heterogeneous surface. The optimal solution pH for phosphate removal was approximately 5.0 because of electrostatic interaction effects. Meanwhile, the decrease in P uptake with increasing ion strength suggested that phosphate adsorption occurred through an outer-sphere complex. Phosphates would compete for adsorption sites on the surface of MODAO in the presence of fluoride ion or sulfate. In addition, the spectroscopic analysis results of Fourier transform infrared spectroscopy and X-ray photoemission spectroscopy indicated that removal mechanisms of phosphate primarily include adhesion to surface hydroxyl groups and ligand exchange.
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Affiliation(s)
- Kun Wu
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China,
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16
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Hu Y, Li Q, Lee B, Jun YS. Aluminum affects heterogeneous Fe(III) (Hydr)oxide nucleation, growth, and ostwald ripening. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 48:299-306. [PMID: 24289329 DOI: 10.1021/es403777w] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Heterogeneous coprecipitation of iron and aluminum oxides is an important process for pollutant immobilization and removal in natural and engineered aqueous environments. Here, using a synchrotron-based small-angle X-ray scattering technique, we studied heterogeneous nucleation and growth of Fe(III) (hydr)oxide on quartz under conditions found in acid mine drainage (at pH = 3.7 ± 0.2, [Fe(3+)] = 10(-4) M) with different initial aqueous Al/Fe ratios (0:1, 1:1, and 5:1). Interestingly, although the atomic ratios of Al/Fe in the newly formed Fe(III) (hydr)oxide precipitates were less than 1%, the in situ particle size and volume evolutions of the precipitates on quartz were significantly influenced by aqueous Al/Fe ratios. At the end of the 3 h experiments, with aqueous Al/Fe ratios of 0:1, 1:1, and 5:1, the average radii of gyration of particles on quartz were 5.7 ± 0.3, 4.6 ± 0.1, and 3.7 ± 0.3 nm, respectively, and the ratio of total particle volumes on quartz was 1.7:3.4:1.0. The Fe(III) (hydr)oxide precipitates were poorly crystallized, and were positively charged in all solutions. In the presence of Al(3+), Al(3+) adsorption onto quartz changed the surface charge of quartz from negative to positive, which caused the slower heterogeneous growth of Fe(III) (hydr)oxide on quartz. Furthermore, Al affected the amount of water included in the Fe(III) (hydr)oxides, which can influence their adsorption capacity. This study yielded important information usable for pollutant removal not only in natural environments, but also in engineered water treatment processes.
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Affiliation(s)
- Yandi Hu
- Department of Energy, Environmental and Chemical Engineering, Washington University , St. Louis, Missouri 63130, United States
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17
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Hofmann A, Vantelon D, Montargès-Pelletier E, Villain F, Gardoll O, Razafitianamaharavo A, Ghanbaja J. Interaction of Fe(III) and Al(III) during hydroxylation by forced hydrolysis: The nature of Al–Fe oxyhydroxy co-precipitates. J Colloid Interface Sci 2013; 407:76-88. [DOI: 10.1016/j.jcis.2013.06.020] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Revised: 06/06/2013] [Accepted: 06/09/2013] [Indexed: 11/30/2022]
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18
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Hu Y, Neil C, Lee B, Jun YS. Control of heterogeneous Fe(III) (hydr)oxide nucleation and growth by interfacial energies and local saturations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:9198-9206. [PMID: 23875694 DOI: 10.1021/es401160g] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
To predict the fate of aqueous pollutants, a better understanding of heterogeneous Fe(III) (hydr)oxide nucleation and growth on abundant mineral surfaces is needed. In this study, we measured in situ heterogeneous Fe(III) (hydr)oxide nucleation and growth on quartz, muscovite, and corundum (Al2O3) in 10(-4) M Fe(III) solution (in 10 mM NaNO3 at pH = 3.7 ± 0.2) using grazing incidence small-angle X-ray scattering (GISAXS). Interestingly, both the fastest heterogeneous nucleation and slowest growth occurred on corundum. To elucidate the mechanisms, zeta potential and water contact angle measurements were conducted. Electrostatic forces between the charged Fe(III) (hydr)oxide polymeric embryos and substrate surfaces-which affect local saturations near the substrate surfaces-controlled heterogeneous growth rates. Water contact angles (7.5° ± 0.7, 22.8° ± 1.7, and 44.8° ± 3.7 for quartz, muscovite, and corundum, respectively) indicate that corundum has the highest substrate-water interfacial energy. Furthermore, a comparison of structural mismatches between the substrates and precipitates indicates a lowest precipitate-substrate interfacial energy for corundum. The fastest nucleation on corundum suggests that interfacial energies in the solution-substrate-precipitate system controlled heterogeneous nucleation rates. The unique information provided here bolsters our understanding of nanoparticle-mineral surface interactions, mineral surface modification by iron oxide coating, and pollutant transport.
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Affiliation(s)
- Yandi Hu
- Department of Energy, Environmental & Chemical Engineering, Washington University, St. Louis, Missouri 63130, USA
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19
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Haraguchi D, Tokoro C, Oda Y, Owada S. Sorption Mechanisms of Arsenate in Aqueous Solution during Coprecipitation with Aluminum Hydroxide. JOURNAL OF CHEMICAL ENGINEERING OF JAPAN 2013. [DOI: 10.1252/jcej.12we168] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Daisuke Haraguchi
- Graduate School of Creative Science and Engineering, Waseda University
| | | | - Yuji Oda
- Graduate School of Creative Science and Engineering, Waseda University
| | - Shuji Owada
- Faculty of Science and Engineering, Waseda University
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20
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Jia Y, Zhang D, Pan R, Xu L, Demopoulos GP. A novel two-step coprecipitation process using Fe(III) and Al(III) for the removal and immobilization of arsenate from acidic aqueous solution. WATER RESEARCH 2012; 46:500-508. [PMID: 22142599 DOI: 10.1016/j.watres.2011.11.045] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2011] [Revised: 11/09/2011] [Accepted: 11/15/2011] [Indexed: 05/31/2023]
Abstract
Lime neutralization and coprecipitation of arsenate with iron is widely practiced for the removal and immobilization of arsenic from mineral processing effluents. However, the stability of the generated iron-arsenate coprecipitate is still of concern. In this work, we developed a two-step coprecipitation process involving the use of iron and aluminum and tested the stability of the resultant coprecipitates. The two-step Fe-As-Fe or Fe-As-Al coprecipitation process involved an initial Fe/As = 2 coprecipitation at pH4 to remove arsenic from water down to 0.25 mg/L, followed by introduction of iron or aluminum (Fe/As = 2, Al/As = 1.5 or 2). The two-step coprecipitates showed higher stability than traditional Fe/As = 4 coprecipitate under both oxic and anoxic conditions. Leaching stability was enhanced when aluminum was applied in the second step. The use of aluminum in the second step also inhibited microbial mediated arsenate reduction and arsenic remobilization. The results suggest that the two-step coprecipitation process is superior to conventional coprecipitation methods with respect to the stability of the generated arsenic-bearing solid waste. The use of Al in the second step is better than Fe to enhance the stability. This work may have important implications to the development of new technologies for efficient arsenic removal from hydrometallurgical solutions and safe disposal in both oxic and anoxic environment.
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Affiliation(s)
- Yongfeng Jia
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China.
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21
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Li W, Cao CY, Wu LY, Ge MF, Song WG. Superb fluoride and arsenic removal performance of highly ordered mesoporous aluminas. JOURNAL OF HAZARDOUS MATERIALS 2011; 198:143-150. [PMID: 22061441 DOI: 10.1016/j.jhazmat.2011.10.025] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 10/05/2011] [Accepted: 10/06/2011] [Indexed: 05/31/2023]
Abstract
Highly ordered mesoporous aluminas and calcium-doped aluminas were synthesized through a facile and reproducible method. Their fluoride adsorption characteristics, including adsorption isotherms, adsorption kinetics, the effect of pH and co-existing anions were investigated. These materials exhibited strong affinity to fluoride ions and extremely high defluoridation capacities. The highest defluoridation capacity value reached 450 mg/g. These materials also showed superb arsenic removal ability. 1g of mesoporous alumina was able to treat 200 kg of arsenic contaminated water with a pH value of 7, reducing the concentration of arsenate from 100 ppb to 1 ppb.
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Affiliation(s)
- Wei Li
- Key Laboratory for Molecular Nanostructures and Nanotechnology, Institute of Chemistry, Beijing National Laboratory for Molecular Sciences (BNLMS), Chinese Academy of Sciences, Beijing, PR China
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22
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Liu YT, Hesterberg D. Phosphate bonding on noncrystalline Al/Fe-hydroxide coprecipitates. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2011; 45:6283-9. [PMID: 21714572 DOI: 10.1021/es201597j] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Poorly crystalline minerals have high sorption capacities for environmentally important chemical species, but molecular-level mechanisms of sorption on complex mineral assemblages remain largely unknown. We determined the distribution of orthophosphate (PO(4)) bonding between Al and Fe in relation to structural properties of Al/Fe-hydroxide coprecipitates. Phosphate was sorbed at concentrations between 0.042 and 0.162 mol P mol(-1) Al+Fe on coprecipitates containing 0, 20, 50, 75, or 100 mol % of metal as Al. Phosphorus XANES analyses showed preferential bonding of PO(4) for Al on coprecipitates with 20 and 50 mol % Al, and no preference for either metal at 75 mol % Al, consistent with X-ray photoelectron spectroscopy (XPS) analyses of near-surface metal distributions. Structural ordering and the Fe-hydroxide domain size in coprecipitates decreased with increasing Al proportion, as shown by X-ray diffraction (XRD) and Fe EXAFS analyses. Structural interactions in coprecipitates imparted unique PO(4) sorption properties compared with isolated Al- or Fe-hydroxide.
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Affiliation(s)
- Yu-Ting Liu
- Department of Soil Science, North Carolina State University, Raleigh, North Carolina 27695, United States
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23
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Tokoro C, Yatsugi Y, Koga H, Owada S. Sorption mechanisms of arsenate during coprecipitation with ferrihydrite in aqueous solution. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2010; 44:638-643. [PMID: 20014828 DOI: 10.1021/es902284c] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Dilute arsenate (As(V)) coprecipitation by ferrihydrite was investigated to determine if treatment of acid mine drainage containing dilute As(V) using coprecipitation is feasible. The sorption density obtained at pH 5 and 7 was nearly identical when As(V) was coprecipitated with ferrihydrite, while it was higher at pH 5 when As(V) was adsorbed on the ferrihydrite. The high sorption density of As(V) to ferrihydrite in coprecipitation with 1-h reaction time suggested that coprecipitation occurs via both adsorption and precipitation. Furthermore, the relationship between residual As(V) and sorption density revealed a BET-type isotherm, with a transition point from a low residual As(V) concentration to a high residual As(V) concentration being observed for all initial As(V) concentrations between 0.15 and 0.44 mmol/dm(3) when the initial molar ratio was 0.56 at pH 5 and 7. X-ray diffraction and the zeta potential revealed that the transition point from surface complexation to precipitation was obtained when the initial As/Fe ratio was 0.4 or 0.5. When dilute As(V) was coprecipitated with ferrihydrite at pH 5 and 7, it was primarily adsorbed as a surface complex when the initial molar ratio was As/Fe < 0.4, while a ferric arsenate and surface complex was formed when this ratio was >or= 0.4.
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Affiliation(s)
- Chiharu Tokoro
- Department of Creative Science and Engineering, Faculty of Science and Engineering, Waseda University, Tokyo 169-8555, Japan.
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