1
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Ceballos E, Cama J, Soler JM, Frei R. Release and mobility of hexavalent chromium in contaminated soil with chemical factory waste: Experiments, Cr isotope analysis and reactive transport modeling. J Hazard Mater 2023; 451:131193. [PMID: 36931219 DOI: 10.1016/j.jhazmat.2023.131193] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 03/05/2023] [Accepted: 03/09/2023] [Indexed: 06/18/2023]
Abstract
Our study focused on the leaching processes in soil contaminated with hexavalent chromium (Cr(VI)), traced to industrial waste from a disused site and resulting in groundwater contamination. Mineral and geochemical characterization of the soil by means of XRD, SEM-EDS, total digestion and sequential extractions revealed that the main Cr content was from solid waste located in the upper meter of the soil profile. Flow-through and column experiments were carried out to investigate the processes responsible for Cr(VI) release. Cr(VI) mobility along the soil profile was also assessed. Moreover, Cr isotope signatures were used to evaluate a potential Cr(VI) reduction process, which preferably could immobilize toxic Cr(VI) complexes. One-dimensional (1D) numerical simulations reproduced the Cr(VI) release from the flow-through experiment containing the Cr(VI) rich-solid waste and also the Cr(VI) mobility along the column experiment. These results enabled us to interpret quantitatively the processes resulting in Cr(VI) contamination and mobility along the soil profile. Cr(VI) was released from dissolving Cr(VI)-rich phases (e.g., sodium chromate, Cr(VI)-hydrocalumite and Cr(VI)-ettringite) of the solid waste layer. Cr(VI) reduction and Cr(VI) adsorption did not take place along the column. Such accurate characterization of these processes is necessary for the mitigation of Cr(VI) mobility in contaminated soils.
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Affiliation(s)
- Elina Ceballos
- Instituto de Hidrología de Llanuras "Dr. Eduardo Jorge Usunoff"(IHLLA), CONICET-UNCPBA-CIC, 7300 Azul, Buenos Aires, Argentina.
| | - Jordi Cama
- Institute of Environmental Assessment and Water Research (IDAEA), CSIC, 08034 Barcelona, Catalonia, Spain
| | - Josep M Soler
- Institute of Environmental Assessment and Water Research (IDAEA), CSIC, 08034 Barcelona, Catalonia, Spain
| | - Robert Frei
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
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2
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Carrero S, Fernandez-Martinez A, Pérez-López R, Cama J, Dejoie C, Nieto JM. Effects of aluminum incorporation on the schwertmannite structure and surface properties. Environ Sci Process Impacts 2022; 24:1383-1391. [PMID: 35838030 DOI: 10.1039/d2em00029f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Schwertmannite is a common nanomineral in acid sulfate environments such as Acid Mine Drainage (AMD) and Acid Sulfate Soils (ASS). Its high surface area and positively charged surface result in a strong affinity towards toxic oxyanions such as arsenate in solution. However, natural precipitation of schwertmannite also involves the accumulation of other impurities, in particular aluminum, an element that is often incorporated into the structure of Fe-oxide minerals, such as goethite and ferrihydrite, affecting their structural and surface properties. However, little is known about the effect of Al incorporation in schwertmannite on the removal capacity of toxic oxyanions found in AMD and ASS (e.g. arsenate). In this paper, schwertmannite samples with variable Al concentration were synthetized and employed in arsenate adsorption isotherm experiments at a constant pH of 3.5. Solid samples before and after arsenate adsorption were characterized using high energy X-ray diffraction and pair distribution function analyses in order to identify structural differences correlated with the Al content as well as variations in the coordination of arsenate adsorbed on the mineral surface. These analyses showed limited Al accumulation on schwertmannite (up to 5%) with a low effect on its structure. The maximum arsenate sorption capacity (258 mmolH2AsO4 molFe-1) was in the range of that with pure schwertmannite, but a higher proportion of inner-sphere coordination was observed. Finally, Al was found to desorb from schwertmannite, with adsorbed arsenate preventing this effect and increasing the stability of the mineral. These results are useful to interpret observations from the field, in particular from river water affected by AMD and ASS, where similar conditions are observed, and where aluminum incorporation is expected.
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Affiliation(s)
- Sergio Carrero
- Institute of Environmental Assessment and Water Research (IDÆA-CSIC), 08034, Barcelona, Spain.
| | | | - Rafael Pérez-López
- Department of Earth Sciences & Research Center on Natural Resources, Health and the Environment, University of Huelva, Campus 'El Carmen', 21071, Huelva, Spain
| | - Jordi Cama
- Institute of Environmental Assessment and Water Research (IDÆA-CSIC), 08034, Barcelona, Spain.
| | - Catherine Dejoie
- European Synchrotron Radiation Facility, 71 avenue des Martyrs, Grenoble, 3800, France
| | - José Miguel Nieto
- Department of Earth Sciences & Research Center on Natural Resources, Health and the Environment, University of Huelva, Campus 'El Carmen', 21071, Huelva, Spain
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3
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Palau J, Benaiges-Fernandez R, Offeddu F, Urmeneta J, Soler JM, Cama J, Dold B. Release of trace elements during bioreductive dissolution of magnetite from metal mine tailings: Potential impact on marine environments. Sci Total Environ 2021; 788:147579. [PMID: 34023600 DOI: 10.1016/j.scitotenv.2021.147579] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 05/01/2021] [Accepted: 05/02/2021] [Indexed: 06/12/2023]
Abstract
Adverse impacts of mine tailings on water and sediments quality are major worldwide environmental problems. Due to the environmental issues associated with the deposition of mine tailings on land, a controversial discussed alternative is submarine tailings disposal (STD). However, Fe(III) bioreduction of iron oxides (e.g., magnetite) in the tailings disposed might cause toxic effects on coastal environments due to the release of different trace elements (TEs) contained in the oxides. To study the extent and kinetics of magnetite bioreduction under marine conditions and the potential release of TEs, a number of batch experiments with artificial seawater (pH 8.2) and a marine microbial strain (Shewanella loihica) were performed using several magnetite ore samples from different mines and a mine tailings sample. The elemental composition of the magnetite determined in the tailings showed relatively high amounts of TEs (e.g., Mn, Zn, Co) compared with those of the magnetite ore samples (LA-ICP-MS and EMPA analyses). The experiments were conducted at 10 °C in the dark for up to 113 days. Based on the consumption of lactate and production of acetate and aqueous Fe(II) over time, the magnitude of Fe(III) bioreduction was calculated using a geochemical model including Monod kinetics. Model simulations reproduced the release of iron and TEs observed throughout the experiments, e.g., Mn (up to 203 μg L-1), V (up to 79 μg L-1), As (up to 17 μg L-1) and Cu (up to 328 μg L-1), suggesting a potential contamination of pore water by STD. Therefore, the results of this study can help to better evaluate the potential impacts of STD.
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Affiliation(s)
- Jordi Palau
- Institute of Environmental Assessment and Water Research (IDAEA), CSIC, Barcelona 08034, Catalonia, Spain; University of Barcelona, Barcelona 08028, Catalonia, Spain.
| | - Robert Benaiges-Fernandez
- Institute of Environmental Assessment and Water Research (IDAEA), CSIC, Barcelona 08034, Catalonia, Spain; University of Barcelona, Barcelona 08028, Catalonia, Spain
| | - Francesco Offeddu
- Institute of Environmental Assessment and Water Research (IDAEA), CSIC, Barcelona 08034, Catalonia, Spain
| | - Jordi Urmeneta
- University of Barcelona, Barcelona 08028, Catalonia, Spain; Biodiversity Research Institute (IRBio), University of Barcelona, Barcelona 08028, Catalonia, Spain
| | - Josep M Soler
- Institute of Environmental Assessment and Water Research (IDAEA), CSIC, Barcelona 08034, Catalonia, Spain
| | - Jordi Cama
- Institute of Environmental Assessment and Water Research (IDAEA), CSIC, Barcelona 08034, Catalonia, Spain
| | - Bernhard Dold
- Pontifical Catholic University of Peru (PUCP), San Miguel, Lima, Peru; SUMIRCO, San Pedro de la Paz, Chile
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4
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Cama J, Leszczynski R, Tang PK, Khalid A, Lok V, Dowson CG, Ebata A. To Push or To Pull? In a Post-COVID World, Supporting and Incentivizing Antimicrobial Drug Development Must Become a Governmental Priority. ACS Infect Dis 2021; 7:2029-2042. [PMID: 33606496 PMCID: PMC7931625 DOI: 10.1021/acsinfecdis.0c00681] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The COVID-19 pandemic has refocused attention worldwide on the dangers of infectious diseases, in terms of both global health and the effects on the world economy. Even in high income countries, health systems have been found wanting in dealing with the new infectious agent. However, the even greater long-term danger of antimicrobial resistance in pathogenic bacteria and fungi is still under-appreciated, especially among the general public. Although antimicrobial drug development faces significant scientific challenges, the gravest challenge at the moment appears to be economic, where the lack of a viable market has led to a collapse in drug development pipelines. There is therefore a critical need for governments across the world to further incentivize the development of antimicrobials. Most incentive strategies over the past decade have focused on so-called "push" incentives that bridge the costs of antimicrobial research and development, but these have been insufficient for reviving the pipeline. In this Perspective, we analyze the current incentive strategies in place for antimicrobial drug development, and focus on "pull" incentives, which instead aim to improve revenue generation and thereby resolve the antimicrobial market failure challenge. We further analyze these incentives in a broader "One Health" context and stress the importance of developing and enforcing strict protocols to ensure appropriate manufacturing practices and responsible use. Our analysis reiterates the importance of international cooperation, coordination across antimicrobial research, and sustained funding in tackling this significant global challenge. A failure to invest wisely and continuously to incentivize antimicrobial pipelines will have catastrophic consequences for global health and wellbeing in the years to come.
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Affiliation(s)
- J. Cama
- Living
Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, U.K.
- College
of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF, U.K.
- ,
| | - R. Leszczynski
- Polygeia,
Global Health Student Think Tank, London, U.K.https://www.polygeia.com/
| | - P. K. Tang
- Polygeia,
Global Health Student Think Tank, London, U.K.https://www.polygeia.com/
- Faculty
of Life Sciences and Medicine, King’s
College London, Great
Maze Pond, London SE1 1UK, U.K.
| | - A. Khalid
- Polygeia,
Global Health Student Think Tank, London, U.K.https://www.polygeia.com/
- School
of Clinical Medicine, University of Cambridge, Cambridge CB2 0SP, U.K.
| | - V. Lok
- Polygeia,
Global Health Student Think Tank, London, U.K.https://www.polygeia.com/
- School of
Biological and Chemical Sciences, Queen
Mary University of London, Mile End Road, London E1 4NS, U.K.
| | - C. G. Dowson
- School
of Life Sciences, Gibbet Hill Campus, University
of Warwick, Coventry CV4 7AL, U.K.
- Antibiotic
Research U.K., Genesis 5, York Science Park, Heslington, York YO10 5DQ, U.K.
| | - A. Ebata
- Institute
of Development Studies, Library Road, Brighton BN1 9RE, U.K.
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5
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Benaiges-Fernandez R, Offeddu FG, Margalef-Marti R, Palau J, Urmeneta J, Carrey R, Otero N, Cama J. Geochemical and isotopic study of abiotic nitrite reduction coupled to biologically produced Fe(II) oxidation in marine environments. Chemosphere 2020; 260:127554. [PMID: 32688313 DOI: 10.1016/j.chemosphere.2020.127554] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 06/25/2020] [Accepted: 06/27/2020] [Indexed: 06/11/2023]
Abstract
Estuarine sediments are often characterized by abundant iron oxides, organic matter, and anthropogenic nitrogen compounds (e.g., nitrate and nitrite). Anoxic dissimilatory iron reducing bacteria (e.g., Shewanella loihica) are ubiquitous in these environments where they can catalyze the reduction of Fe(III) (oxyhydr)oxides, thereby releasing aqueous Fe(II). The biologically produced Fe(II) can later reduce nitrite to form nitrous oxide. The effect on nitrite reduction by both biologically produced and artificially amended Fe(II) was examined experimentally. Ferrihydrite was reduced by Shewanella loihica in a batch reaction with an anoxic synthetic sea water medium. Some of the Fe(II) released by S. loihica adsorbed onto ferrihydrite, which was involved in the transformation of ferrihydrite to magnetite. In a second set of experiments with identical medium, no microorganism was present, instead, Fe(II) was amended. The amount of solid-bound Fe(II) in the experiments with bioproduced Fe(II) increased the rate of abiotic NO2- reduction with respect to that with synthetic Fe(II), yielding half-lives of 0.07 and 0.47 d, respectively. The δ18O and δ15N of NO2- was measured through time for both the abiotic and innoculated experiments. The ratio of ε18O/ε15N was 0.6 for the abiotic experiments and 3.1 when NO2- was reduced by S. loihica, thus indicating two different mechanisms for the NO2- reduction. Notably, there is a wide range of the ε18O/ε15N values in the literature for abiotic and biotic NO2- reduction, as such, the use of this ratio to distinguish between reduction mechanisms in natural systems should be taken with caution. Therefore, we suggest an additional constraint to identify the mechanisms (i.e. abiotic/biotic) controlling NO2- reduction in natural settings through the correlation of δ15N-NO2- and the aqueous Fe(II) concentration.
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Affiliation(s)
- R Benaiges-Fernandez
- Institute of Environmental Assessment and Water Research (IDAEA, CSIC), 08034, Barcelona, Catalonia, Spain; Departament de Genètica, Microbiologia I Estadística, Universitat de Barcelona, 08028, Barcelona, Catalonia, Spain.
| | - F G Offeddu
- Institute of Environmental Assessment and Water Research (IDAEA, CSIC), 08034, Barcelona, Catalonia, Spain
| | - R Margalef-Marti
- Grup MAiMA, SGR Mineralogia Aplicada, Geoquímica I Geomicrobiologia, Departament de Mineralogia, Petrologia I Geologia Aplicada, Facultat de Ciències de La Terra, Universitat de Barcelona (UB), 08028, Barcelona, Catalonia, Spain; Institut de Recerca de L'Aigua (IdRA), Universitat de Barcelona (UB), 08001, Barcelona, Catalonia, Spain
| | - J Palau
- Institute of Environmental Assessment and Water Research (IDAEA, CSIC), 08034, Barcelona, Catalonia, Spain; Grup MAiMA, SGR Mineralogia Aplicada, Geoquímica I Geomicrobiologia, Departament de Mineralogia, Petrologia I Geologia Aplicada, Facultat de Ciències de La Terra, Universitat de Barcelona (UB), 08028, Barcelona, Catalonia, Spain; Institut de Recerca de L'Aigua (IdRA), Universitat de Barcelona (UB), 08001, Barcelona, Catalonia, Spain
| | - J Urmeneta
- Departament de Genètica, Microbiologia I Estadística, Universitat de Barcelona, 08028, Barcelona, Catalonia, Spain; Institut de Recerca de La Biodiversitat (IRBio), Universitat de Barcelona, 08028, Barcelona, Catalonia, Spain
| | - R Carrey
- Grup MAiMA, SGR Mineralogia Aplicada, Geoquímica I Geomicrobiologia, Departament de Mineralogia, Petrologia I Geologia Aplicada, Facultat de Ciències de La Terra, Universitat de Barcelona (UB), 08028, Barcelona, Catalonia, Spain; Institut de Recerca de L'Aigua (IdRA), Universitat de Barcelona (UB), 08001, Barcelona, Catalonia, Spain
| | - N Otero
- Grup MAiMA, SGR Mineralogia Aplicada, Geoquímica I Geomicrobiologia, Departament de Mineralogia, Petrologia I Geologia Aplicada, Facultat de Ciències de La Terra, Universitat de Barcelona (UB), 08028, Barcelona, Catalonia, Spain; Institut de Recerca de L'Aigua (IdRA), Universitat de Barcelona (UB), 08001, Barcelona, Catalonia, Spain; Serra Húnter Fellowship. Generalitat de Catalunya, Catalonia, Spain
| | - J Cama
- Institute of Environmental Assessment and Water Research (IDAEA, CSIC), 08034, Barcelona, Catalonia, Spain
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6
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Benaiges-Fernandez R, Palau J, Offeddu FG, Cama J, Urmeneta J, Soler JM, Dold B. Dissimilatory bioreduction of iron(III) oxides by Shewanella loihica under marine sediment conditions. Mar Environ Res 2019; 151:104782. [PMID: 31514974 DOI: 10.1016/j.marenvres.2019.104782] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 08/30/2019] [Accepted: 09/02/2019] [Indexed: 06/10/2023]
Abstract
Shewanella is a genus of marine bacteria capable of dissimilatory iron reduction (DIR). In the context of deep-sea mining activities or submarine mine tailings disposal, dissimilatory iron reducing bacteria may play an important role in biogeochemical reactions concerning iron oxides placed on the sea bed. In this study, batch experiments were performed to evaluate the capacity of Shewanella loihica PV-4 to bioreduce different iron oxides (ferrihydrite, magnetite, goethite and hematite) under conditions similar to those in anaerobic sea sediments. Results showed that bioreduction of structural Fe(III) via oxidation of labile organic matter occurred in all these iron oxides. Based on the aqueous Fe (II) released, derived Fe(II)/acetate ratios and bioreduction coefficients seem to be only up to about 4% of the theoretical ones, considering the ideal stoichiometry of the reaction. A loss of aqueous Fe (II) was caused by adsorption and mineral transformation processes. Scanning electron microscope images showed that Shewanella lohica was attached to the Fe(III)-oxide surfaces during bioreduction. Our findings suggest that DIR of Fe(III) oxides from mine waste placed in marine environments could result in adverse ecological impacts such as liberation of trace metals in the environment.
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Affiliation(s)
- Robert Benaiges-Fernandez
- Department of Genetics, Microbiology and Statistics, Universitat de Barcelona, Barcelona, Catalonia, Spain; Institute of Environmental Assessment and Water Research (IDAEA, CSIC), Barcelona, Catalonia, Spain.
| | - Jordi Palau
- Institute of Environmental Assessment and Water Research (IDAEA, CSIC), Barcelona, Catalonia, Spain; Department of Mineralogy, Petrology and Applied Geology, Universitat de Barcelona, Barcelona, Catalonia, Spain
| | - Francesco G Offeddu
- Institute of Environmental Assessment and Water Research (IDAEA, CSIC), Barcelona, Catalonia, Spain
| | - Jordi Cama
- Institute of Environmental Assessment and Water Research (IDAEA, CSIC), Barcelona, Catalonia, Spain
| | - Jordi Urmeneta
- Department of Genetics, Microbiology and Statistics, Universitat de Barcelona, Barcelona, Catalonia, Spain; Biodiversity Research Institute (IRBio), Universitat de Barcelona, Barcelona, Catalonia, Spain
| | - Josep M Soler
- Institute of Environmental Assessment and Water Research (IDAEA, CSIC), Barcelona, Catalonia, Spain
| | - Bernhard Dold
- Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden; Sustainable Mining Research & Consultancy EIRL, San Pedro de La Paz, Chile
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7
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Al Nahas K, Cama J, Schaich M, Hammond K, Deshpande S, Dekker C, Ryadnov MG, Keyser UF. A microfluidic platform for the characterisation of membrane active antimicrobials. Lab Chip 2019; 19:837-844. [PMID: 30698187 PMCID: PMC6404476 DOI: 10.1039/c8lc00932e] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 12/05/2018] [Indexed: 05/21/2023]
Abstract
The spread of bacterial resistance against conventional antibiotics generates a great need for the discovery of novel antimicrobials. Polypeptide antibiotics constitute a promising class of antimicrobial agents that favour attack on bacterial membranes. However, efficient measurement platforms for evaluating their mechanisms of action in a systematic manner are lacking. Here we report an integrated lab-on-a-chip multilayer microfluidic platform to quantify the membranolytic efficacy of such antibiotics. The platform is a biomimetic vesicle-based screening assay, which generates giant unilamellar vesicles (GUVs) in physiologically relevant buffers on demand. Hundreds of these GUVs are individually immobilised downstream in physical traps connected to separate perfusion inlets that facilitate controlled antibiotic delivery. Antibiotic efficacy is expressed as a function of the time needed for an encapsulated dye to leak out of the GUVs as a result of antibiotic treatment. This proof-of-principle study probes the dose response of an archetypal polypeptide antibiotic cecropin B on GUVs mimicking bacterial membranes. The results of the study provide a foundation for engineering quantitative, high-throughput microfluidics devices for screening antibiotics.
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Affiliation(s)
- K. Al Nahas
- Cavendish Laboratory
, Univ. of Cambridge
,
JJ Thomson Avenue
, Cambridge CB3 0HE
, UK
.
| | - J. Cama
- Cavendish Laboratory
, Univ. of Cambridge
,
JJ Thomson Avenue
, Cambridge CB3 0HE
, UK
.
| | - M. Schaich
- Cavendish Laboratory
, Univ. of Cambridge
,
JJ Thomson Avenue
, Cambridge CB3 0HE
, UK
.
| | - K. Hammond
- National Physical Laboratory
,
Hampton Road, Teddington
, Middlesex TW11 0LW
, UK
| | - S. Deshpande
- Kavli Institute of Nanoscience
, Delft Univ. of Technology
,
van der Maasweg 9
, Delft 2629 HZ
, Netherlands
| | - C. Dekker
- Kavli Institute of Nanoscience
, Delft Univ. of Technology
,
van der Maasweg 9
, Delft 2629 HZ
, Netherlands
| | - M. G. Ryadnov
- National Physical Laboratory
,
Hampton Road, Teddington
, Middlesex TW11 0LW
, UK
| | - U. F. Keyser
- Cavendish Laboratory
, Univ. of Cambridge
,
JJ Thomson Avenue
, Cambridge CB3 0HE
, UK
.
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8
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Offeddu FG, Cama J, Soler JM, Putnis CV. Direct nanoscale observations of the coupled dissolution of calcite and dolomite and the precipitation of gypsum. Beilstein J Nanotechnol 2014; 5:1245-1253. [PMID: 25161860 PMCID: PMC4142853 DOI: 10.3762/bjnano.5.138] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 07/21/2014] [Indexed: 06/03/2023]
Abstract
In-situ atomic force microscopy (AFM) experiments were performed to study the overall process of dissolution of common carbonate minerals (calcite and dolomite) and precipitation of gypsum in Na2SO4 and CaSO4 solutions with pH values ranging from 2 to 6 at room temperature (23 ± 1 °C). The dissolution of the carbonate minerals took place at the (104) cleavage surfaces in sulfate-rich solutions undersaturated with respect to gypsum, by the formation of characteristic rhombohedral-shaped etch pits. Rounding of the etch pit corners was observed as solutions approached close-to-equilibrium conditions with respect to calcite. The calculated dissolution rates of calcite at pH 4.8 and 5.6 agreed with the values reported in the literature. When using solutions previously equilibrated with respect to gypsum, gypsum precipitation coupled with calcite dissolution showed short gypsum nucleation induction times. The gypsum precipitate quickly coated the calcite surface, forming arrow-like forms parallel to the crystallographic orientations of the calcite etch pits. Gypsum precipitation coupled with dolomite dissolution was slower than that of calcite, indicating the dissolution rate to be the rate-controlling step. The resulting gypsum coating partially covered the surface during the experimental duration of a few hours.
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Affiliation(s)
- Francesco Giancarlo Offeddu
- Institute of Environmental Assessment and Water Research (IDAEA), CSIC, Jordi Girona 18-26, 08034 Barcelona, Catalonia, Spain
| | - Jordi Cama
- Institute of Environmental Assessment and Water Research (IDAEA), CSIC, Jordi Girona 18-26, 08034 Barcelona, Catalonia, Spain
| | - Josep Maria Soler
- Institute of Environmental Assessment and Water Research (IDAEA), CSIC, Jordi Girona 18-26, 08034 Barcelona, Catalonia, Spain
| | - Christine V Putnis
- Institut für Mineralogie, University of Münster, Corrensstrasse 24 D-48149, Münster, Germany
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9
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Cama J, Chimerel C, Pagliara S, Javer A, Keyser UF. A label-free microfluidic assay to quantitatively study antibiotic diffusion through lipid membranes. Lab Chip 2014; 14:2303-2308. [PMID: 24825393 DOI: 10.1039/c4lc00217b] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
With the rise in antibiotic resistance amongst pathogenic bacteria, the study of antibiotic activity and transport across cell membranes is gaining widespread importance. We present a novel, label-free microfluidic assay that quantifies the permeability coefficient of a broad spectrum fluoroquinolone antibiotic, norfloxacin, across lipid membranes using the UV autofluorescence of the drug. We use giant lipid vesicles as highly controlled model systems to study the diffusion through lipid membranes. Our technique directly determines the permeability coefficient without requiring the measurement of the partition coefficient of the antibiotic.
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Affiliation(s)
- J Cama
- Biological and Soft Systems, Dept. of Physics, Univ. of Cambridge, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK.
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10
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Oliva J, Cama J, Cortina JL, Ayora C, De Pablo J. Biogenic hydroxyapatite (Apatite II™) dissolution kinetics and metal removal from acid mine drainage. J Hazard Mater 2012; 213-214:7-18. [PMID: 22341745 DOI: 10.1016/j.jhazmat.2012.01.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Revised: 01/09/2012] [Accepted: 01/09/2012] [Indexed: 05/31/2023]
Abstract
Apatite II™ is a biogenic hydroxyapatite (expressed as Ca(5)(PO(4))OH) derived from fish bone. Using grains of Apatite II™ with a fraction size between 250 and 500 μm, batch and flow-through experiments were carried out to (1) determine the solubility constant for the dissolution reaction Ca(5)(PO(4))(3)(OH) ⇔ 5Ca(2+) + 3PO(4)(3-) + OH(-), (2) obtain steady-state dissolution rates over the pH range between 2.22 and 7.14, and (3) study the Apatite II™'s mechanisms to remove Pb(2+), Zn(2+), Mn(2+), and Cu(2+) from metal polluted water as it dissolves. The logK(S) value obtained was -50.8±0.82 at 25 °C. Far-from-equilibrium fish-bone hydroxyapatite dissolution rates decrease by increasing pH. Assuming that the dissolution reaction is controlled by fast adsorption of a proton on a specific surface site that dominates through the pH range studied, probably ≡PO(-), followed by a slow hydrolysis step, the dissolution rate dependence is expressed in mol m(-2) s(-1) as where Rate(25 °C) = -8.9 × 10(-10) × [9.96 × 10(5) × a(H+)]/[1 + 9.96 × 10(5) × a(H+)] where a(H+) is the proton activity in solution. Removal of Pb(2+), Zn(2+), Mn(2+) and Cu(2+) was by formation of phosphate-metal compounds on the Apatite II™ substrate, whereas removal of Cd(2+) was by surface adsorption. Increase in pH enhanced the removal of aqueous heavy metals. Using the kinetic parameters obtained (e.g., dissolution rate and pH-rate dependence law), reactive transport simulations reproduced the experimental variation of pH and concentrations of Ca, P and toxic divalent metal in a column experiment filled with Apatite II™ that was designed to simulate the Apatite II™-metal polluted water interaction.
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Affiliation(s)
- J Oliva
- Department of Mining Engineering and Natural Resources, Politechnical University of Catalunya, Bases de Manresa 61-73, Manresa 08242, Catalonia, Spain
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Barbieri M, Carrera J, Sanchez-Vila X, Ayora C, Cama J, Köck-Schulmeyer M, López de Alda M, Barceló D, Tobella Brunet J, Hernández García M. Microcosm experiments to control anaerobic redox conditions when studying the fate of organic micropollutants in aquifer material. J Contam Hydrol 2011; 126:330-345. [PMID: 22115096 DOI: 10.1016/j.jconhyd.2011.09.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 08/20/2011] [Accepted: 09/09/2011] [Indexed: 05/31/2023]
Abstract
The natural processes occurring in subsurface environments have proven to effectively remove a number of organic pollutants from water. The predominant redox conditions revealed to be one of the controlling factors. However, in the case of organic micropollutants the knowledge on this potential redox-dependent behavior is still limited. Motivated by managed aquifer recharge practices microcosm experiments involving aquifer material, settings potentially feasible in field applications, and organic micropollutants at environmental concentrations were carried out. Different anaerobic redox conditions were promoted and sustained in each set of microcosms by adding adequate quantities of electron donors and acceptors. Whereas denitrification and sulfate-reducing conditions are easily achieved and maintained, Fe- and Mn-reduction are strongly constrained by the slower dissolution of the solid phases commonly present in aquifers. The thorough description and numerical modeling of the evolution of the experiments, including major and trace solutes and dissolution/precipitation of solid phases, have been proven necessary to the understanding of the processes and closing the mass balance. As an example of micropollutant results, the ubiquitous beta-blocker atenolol is completely removed in the experiments, the removal occurring faster under more advanced redox conditions. This suggests that aquifers constitute a potentially efficient alternative water treatment for atenolol, especially if adequate redox conditions are promoted during recharge and long enough residence times are ensured.
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Affiliation(s)
- Manuela Barbieri
- GHS, Institute of Environmental Assessment and Water Research (IDAEA), CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain.
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Oliva J, De Pablo J, Cortina JL, Cama J, Ayora C. Removal of cadmium, copper, nickel, cobalt and mercury from water by Apatite II™: column experiments. J Hazard Mater 2011; 194:312-323. [PMID: 21871722 DOI: 10.1016/j.jhazmat.2011.07.104] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Revised: 07/25/2011] [Accepted: 07/28/2011] [Indexed: 05/31/2023]
Abstract
Apatite II™, a biogenic hydroxyapatite, was evaluated as a reactive material for heavy metal (Cd, Cu, Co, Ni and Hg) removal in passive treatments. Apatite II™ reacts with acid water by releasing phosphates that increase the pH up to 6.5-7.5, complexing and inducing metals to precipitate as metal phosphates. The evolution of the solution concentration of calcium, phosphate and metals together with SEM-EDS and XRD examinations were used to identify the retention mechanisms. SEM observation shows low-crystalline precipitate layers composed of P, O and M. Only in the case of Hg and Co were small amounts of crystalline phases detected. Solubility data values were used to predict the measured column experiment values and to support the removal process based on the dissolution of hydroxyapatite, the formation of metal-phosphate species in solution and the precipitation of metal phosphate. Cd(5)(PO(4))(3)OH(s), Cu(2)(PO(4))OH(s), Ni(3)(PO(4))(2)(s), Co(3)(PO(4))(2)8H(2)O(s) and Hg(3)(PO(4))(2)(s) are proposed as the possible mineral phases responsible for the removal processes. The results of the column experiments show that Apatite II™ is a suitable filling for permeable reactive barriers.
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Affiliation(s)
- Josep Oliva
- Department of Mining Engineering and Natural Resources, Universitat Politècnica de Catalunya, Bases de Manresa 61-73, 08242 Manresa, Catalonia, Spain
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Cama J, Nagra S, Chang A. Left-sided congenital abdominal wall defect and intestinal malformation--a rare case. Pac Health Dialog 2011; 17:154-156. [PMID: 23008980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A case report of a female newborn with a rare congenital abdominal wall defect associated with intestinal malformation. To our knowledge, only a few case reports of left sided congenital abdominal wall defect with this type of anomalies have been reported in the world literatures and this is the first in Fiji. This case brought numerous challenges to the team in terms of defining the pathology, role of undertaking surgery, providing supportive and nutritional therapy to a neonate and the ethical dilemma with the management in a developing country.
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Affiliation(s)
- J Cama
- Department of Medical Sciences, Fiji School of Medicine/Colonial War Memorial Hospital, Suva.
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Oliva J, De Pablo J, Cortina JL, Cama J, Ayora C. The use of Apatite II™ to remove divalent metal ions zinc(II), lead(II), manganese(II) and iron(II) from water in passive treatment systems: column experiments. J Hazard Mater 2010; 184:364-374. [PMID: 20851514 DOI: 10.1016/j.jhazmat.2010.08.045] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 05/07/2010] [Accepted: 08/16/2010] [Indexed: 05/29/2023]
Abstract
The conventional passive treatments for remediation of acid mine drainage using calcite are not totally efficient in the removal of certain heavy metal ions. Although pH increases to 6-7 and promotes the precipitation of trivalent and some divalent metals as hydroxides and carbonates, the remaining concentrations of some divalent metals ions do not fulfill the environmental regulations. In this study, Apatite II™, a biogenic hydroxyapatite, is used as an alternative reactive material to remove Zn(II), Pb(II), Mn(II) and Fe(II). Apatite II™ reacted with acid water releasing phosphate and increasing pH up to 6.5-7, inducing metals to precipitate mainly as metal-phosphates: zinc precipitated as hopeite, Zn(3)(PO(4))(2)·4H(2)O, lead as pyromorfite, Pb(5)(PO(4))(3)OH, manganese as metaswitzerite, Mn(3)(PO(4))(2)·4H(2)O and iron as vivianite, Fe(3)(PO(4))(2)·8H(2)O. Thus, metal concentrations from 30 to 75 mg L(-1) in the inflowing water were depleted to values below 0.10 mg L(-1). Apatite II™ dissolution is sufficiently fast to treat flows as high as 50 m/a. For reactive grain size of 0.5-3mm, the treatment system ends due to coating of the grains by precipitates, especially when iron and manganese are present in the solution.
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Affiliation(s)
- Josep Oliva
- Department of Mining Engineering and Natural Resources, Universitat Politècnica de Catalunya, Bases de Manresa 61-73, 08242 Manresa, Catalonia, Spain
| | - Joan De Pablo
- Department of Chemical Engineering, Universitat Politècnica de Catalunya, Diagonal 647, 08028 Barcelona, Catalonia, Spain
| | - José-Luis Cortina
- Department of Chemical Engineering, Universitat Politècnica de Catalunya, Diagonal 647, 08028 Barcelona, Catalonia, Spain; Water Technology Center, CETaqua, Paseo de los Tilos 3, 08034 Barcelona, Spain.
| | - Jordi Cama
- Institute of Environmental Assessment and Water Research, IDAEA, CSIC, Jordi Girona 18, 08034 Barcelona, Catalonia, Spain
| | - Carlos Ayora
- Institute of Environmental Assessment and Water Research, IDAEA, CSIC, Jordi Girona 18, 08034 Barcelona, Catalonia, Spain
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Asta MP, Ayora C, Acero P, Cama J. Field rates for natural attenuation of arsenic in Tinto Santa Rosa acid mine drainage (SW Spain). J Hazard Mater 2010; 177:1102-1111. [PMID: 20153577 DOI: 10.1016/j.jhazmat.2010.01.034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Revised: 01/04/2010] [Accepted: 01/05/2010] [Indexed: 05/28/2023]
Abstract
Reactive transport modelling of the main processes related to the arsenic natural attenuation observed in the acid mine drainage (AMD) impacted stream of Tinto Santa Rosa (SW Spain) was performed. Despite the simplicity of the kinetic expressions used to deal with arsenic attenuation processes, the model reproduced successfully the major chemical trends observed along the acid discharge. Results indicated that the rate of ferrous iron oxidation was similar to the one obtained in earlier field studies in which microbial catalysis is reported to occur. With regard to the scaled arsenic oxidation rate, it is one order of magnitude faster than the values obtained under laboratory conditions suggesting the existence of a catalytic agent in the natural system. Schwertmannite precipitation rate, which was represented by a simple kinetic expression relying on Fe(III) and pH, was in the range calculated for other AMD impacted sites. Finally, the obtained distribution coefficients used for representing arsenic sorption onto Fe(III) precipitates were lower than those deduced from reported laboratory data. This discrepancy is attributed to a decrease in the schwertmannite arsenate sorption capacity as sulphate increases in the solution.
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Affiliation(s)
- Maria P Asta
- Institute of Environmental Assessment and Water Research (IDAEA), CSIC, 08034 Barcelona, Spain.
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Asta MP, Cama J, Martínez M, Giménez J. Arsenic removal by goethite and jarosite in acidic conditions and its environmental implications. J Hazard Mater 2009; 171:965-972. [PMID: 19628332 DOI: 10.1016/j.jhazmat.2009.06.097] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2009] [Revised: 06/17/2009] [Accepted: 06/17/2009] [Indexed: 05/28/2023]
Abstract
Schwertmannite (Fe(8)O(8)(OH)(5.5)(SO(4))(1.25)), jarosite (KFe(3)(SO(4))(2)(OH)(6)) and goethite (FeOOH) control natural attenuation of arsenic in acid mine drainage (AMD) impacted areas. Batch experiments were conducted to examine the sorption capacity of synthetic goethite and synthetic jarosite at highly acidic pH (1.5-2.5), at two ionic strengths (0.02-0.15 mol dm(-3), NaCl) and at sulphate concentrations in the range of 5 x 10(-3) to 2.8 x 10(-1) mol dm(-3). In the absence of competitive effects of other anions, K-jarosite presents better removal efficiency than goethite for As(V). The maximum sorption capacity is estimated to be 1.2 x 10(-4) and 7.0 x 10(-6)mol m(-2) for jarosite and goethite, respectively, under similar experimental conditions. The variation of arsenic sorbed on goethite as a function of the equilibrium arsenic concentration in solution fits a non-competitive Langmuir isotherm. In the case of K-jarosite, sorption data could not fit a Langmuir or Freundlich isotherm since sulphate-arsenate anion exchange is probably the sorption mechanism. Ionic strength and pH have little effect on the sorption capacity of goethite and jarosite in the small range of pH studied. The presence of sulphate, which is the main anion in AMD natural systems, has a negative effect on arsenic removal since sulphate competes with arsenate for surface sorption sites. Moreover, mobilization of arsenic in the transformation of schwertmannite to jarosite or goethite at pH 2-3 is proposed since the sorption capacities of goethite and K-jarosite are considerably lower than those reported for schwertmannite.
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Affiliation(s)
- María P Asta
- Institute of Environmental Assessment and Water Research (IDAEA), CSIC, 08034 Barcelona, Spain.
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Rötting TS, Cama J, Ayora C, Cortina JL, De Pablo J. Use of caustic magnesia to remove cadmium, nickel, and cobalt from water in passive treatment systems: column experiments. Environ Sci Technol 2006; 40:6438-43. [PMID: 17120577 DOI: 10.1021/es061092g] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
In the present study caustic magnesia obtained from calcination of magnesium carbonate was tested in column experiments as an alternative material for passive remediation systems to remove divalent metals. Caustic magnesia reacts with water to form magnesium hydroxide, which dissolves increasing the pH to values higher than 8.5. At these pH values, cadmium is precipitated as otavite and to a minor amount as a hydroxide. Cobalt and nickel are precipitated as hydroxides which form isostructural solids with brucite. Thus, metal concentrations as high as 75 mg/L in the inflowing water are depleted to values below 10 microg/L. Magnesia dissolution is sufficiently fast to treat flows as high as 0.5 m3/m2 x day. For reactive grain size of 2-4 mm, the column efficiency ends due to coating of the grains by precipitates, especially when iron and aluminum are present in the solution.
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Affiliation(s)
- Tobias Stefan Rötting
- Institute of Earth Sciences Jaume Almera, CSIC, Lluis Solé i Sabarís s/n, 08028 Barcelona, Spain.
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Querol X, Alastuey A, Moreno N, Alvarez-Ayuso E, García-Sánchez A, Cama J, Ayora C, Simón M. Immobilization of heavy metals in polluted soils by the addition of zeolitic material synthesized from coal fly ash. Chemosphere 2006; 62:171-80. [PMID: 16039695 DOI: 10.1016/j.chemosphere.2005.05.029] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2004] [Revised: 05/12/2005] [Accepted: 05/13/2005] [Indexed: 05/03/2023]
Abstract
The use of zeolitic material synthesized from coal fly ash for the immobilization of pollutants in contaminated soils was investigated in experimental plots in the Guadiamar Valley (SW Spain). This area was affected by a pyrite slurry spill in April 1998. Although reclamation activities were completed in a few months, residual pyrite slurry mixed with soil accounted for relatively high leachable levels of trace elements such as Zn, Pb, As, Cu, Sb, Co, Tl and Cd. Phytoremediation strategies were adopted for the final recovery of the polluted soils. The immobilization of metals had previously been undertaken to avoid leaching processes and the consequent groundwater pollution. To this end, 1100 kg of high NaP1 (Na6[(AlO2)6(SiO2)10] .15H2O) zeolitic material was synthesized using fly ash from the Teruel power plant (NE Spain), in a 10 m3 reactor. This zeolitic material was manually applied using different doses (10000-25000 kg per hectare), into the 25 cm topsoil. Another plot (control) was maintained without zeolite. Sampling was carried out 1 and 2 years after the zeolite addition. The results show that the zeolitic material considerably decreases the leaching of Cd, Co, Cu, Ni, and Zn. The sorption of metals in soil clay minerals (illite) proved to be the main cause contributing to the immobilization of these pollutants. This sorption could be a consequence of the rise in pH from 3.3 to 7.6 owing to the alkalinity of the zeolitic material added (caused by traces of free lime in the fly ash, or residual NaOH from synthesis).
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Affiliation(s)
- Xavier Querol
- Institute of Earth Sciences Jaume Almera (CSIC) c/Lluis Solé i Sabarís, s/n, 08028, Barcelona, Spain.
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Cama J, Ayora C, Querol X, Ganor J. Dissolution kinetics of synthetic zeolite NaP1 and its implication to zeolite treatment of contaminated waters. Environ Sci Technol 2005; 39:4871-7. [PMID: 16053086 DOI: 10.1021/es0500512] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The effect of pH on the dissolution kinetics of NaP1 zeolite, which was produced from the alkaline treatment of coal fly ash and may be used for decontamination of acid mine waters, is studied. The sample contains considerable amounts of accessory phases that partly dissolve during the experiment. Therefore, the dissolution rate was estimated during a stage in which the Al/Si ratio was equal to that of NaP1 (0.6). The release rate of these elements is controlled by the dissolution of the zeolite itself during this stage. The dissolution rate of NaP1 slows down with increasing pH in the acidic range, becomes constant at an intermediate pH, and increases with increasing pH in the basic range. The observed changes in rates were described using a rate law based on a surface speciation model. Using this rate law, we calculated the half-life of NaP1 to be about 2 years at near neutral pH and less than 10 days at pH below 3. For the utilization of NaP1 in the treatment of wastewaters or acid mine waters, these short half-lives bear two implications: (1) The treated waters must be kept at near neutral pH, and NaP1 should be added periodically to the treated waters in order to compensate for zeolite loss. (2) In water treatment applications that require a relatively short reaction time, the zeolite removed from the effluents should be kept dry in order to avoid its decomposition and the consequent release of the adsorbed metal to the environment.
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Affiliation(s)
- Jordi Cama
- Department of Environmental Geology, Institute of Earth Sciences Jaume Almera, CSIC, Lluis Solé i Sabarís s/n, Barcelona 08028, Catalonia
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Abstract
The aim of the present study is to compare available surface titration curves of kaolinite, to explain the differences between them, and to constrain their interpretation based on predictions of surface protonation that emerged from dissolution experiments. Comparison of six surface titration curves obtained at 25 degrees C reveals significant discrepancies, both in the shape of the curves and in the pH of the point of zero net proton charge (pH(PZNPC)). Based on an analysis of the different sites available for adsorption on kaolinite surfaces we conclude that different kaolinite samples are expected to have similar pH(PZNPC). Therefore, the major reason for the differences in the observed surface protonation is related to the different ways in which the pH(PZNPC) was determined. To compare the titration curves, some of the curves were recalculated so that the proton surface concentrations of all the titration curves would be zero around pH 5. As a result, we obtained a good agreement between the titration curves. A prediction of the molar fraction of protonated sites was retrieved from modeling of kaolinite dissolution reaction and was compared to the protonation data obtained from surface titration. The model successfully predicts the surface protonation data of most of the surface titrations.
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Affiliation(s)
- Jiwchar Ganor
- Department of Geological and Environmental Sciences, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105, Israel.
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Cortina JL, Lagreca I, De Pablo J, Cama J, Ayora C. Passive in situ remediation of metal-polluted water with caustic magnesia: evidence from column experiments. Environ Sci Technol 2003; 37:1971-1977. [PMID: 12775073 DOI: 10.1021/es026018m] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Passive remediation consists of a permeable system that enables the water to pass through while retaining metals by means of biogeochemical reactions. Conventional passive treatments are based on calcite dissolution. This increases the pH to values between 6 and 7, which are insufficiently high to precipitate divalent metals. Alternative treatments are based on sulfate reduction with organic matter in order to precipitate metal sulfides. However, redox reactions are usually too slow to treat large groundwater flows as currently found in gravel aquifers (>50 m/a). Caustic magnesia obtained from calcination of magnesium carbonate was tested as an alternative material to devising passive remediation systems. Caustic magnesia reacts with water to form magnesium hydroxide, which dissolves, increasing the pH to values higher than 8.5. Then zinc and lead are mainly precipitated as hydroxides, copper is precipitated as hydroxysulfate, and manganese(II) is oxidized and precipitated as manganese(III) oxides. Thus, metal concentrations as high as 75 mg/L in the inflowing water are depleted to values below 0.04 mg/L. Magnesia dissolution is sufficiently fast to treat flows as high as 100 m/a. The new precipitates may lead to a permeability drop in the porous treating system. Mixtures of caustic magnesia and an inert material such as silica sand (approximately 50% of each) have been shown to be as reactive as pure magnesia and permeable for a longer time (more than 10 months and 1000 pore vol).
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Affiliation(s)
- Jose-Luis Cortina
- Department of Chemical Engineering, Universitat Politècnica de Catalunya, Diagonal 647, 08028 Barcelona, Spain.
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