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Silva L.F.O.,Catarinense Institute of Environmental Research and Human Development IPADHC | Hower J.C.,University of Kentucky | Izquierdo M.,CSIC - Institute of Environmental Assessment And Water Research | Querol X.,CSIC - Institute of Environmental Assessment And Water Research
Science of the Total Environment | Year: 2010

Phosphogypsum (CaSO4·2H2O), a by-product of phosphate-rock processing, contains high amounts of impurities such P2O5, F, radioactive elements, organic substances, secondary nanominerals, and ultrafine particles (UFP) enriched in metals and metalloids. In this study, we examine phosphogypsum (PG) collected from abandoned fertilizer industry facility in south Brazil (Santa Catarina state). The fragile nature of nanominerals and UFP assemblages from fertilizer industry systems required novel techniques and experimental approaches. The investigation of the geochemistry of complex nanominerals and UFP assemblages was a prerequisite to accurately assess the environmental and human health risks of contaminants and cost-effective chemical and biogeological remediation strategies. Particular emphasis was placed on the study and characterization of the complex mixed nanominerals and UFP containing potentially toxic elements. Nanometer-sized phases in PG were characterized using energy-dispersive X-ray spectrometer (EDS), field-emission scanning electron microscope (FE-SEM), and high-resolution transmission electron microscopy (HR-TEM) images. The chemical composition and possible correlations with morphology of nanominerals and UFP, as well as aspects of nanominerals and UFP, are discussed in the context of human health exposure, as well as in relation to management of the nanominerals and UFP in PG environments. © 2010 Elsevier B.V.


Quispe D.,University of Huelva | Perez-Lopez R.,University of Huelva | Perez-Lopez R.,CSIC - Institute of Environmental Assessment And Water Research | Silva L.F.O.,Catarinense Institute of Environmental Research and Human Development IPADHC | And 2 more authors.
Fuel | Year: 2012

This paper reports about changes in mobility of hazardous elements contained in coal during combustion at a power plant in Santa Catarina (Brazil) and the environmental impact potential of ashes. Total and mobile element concentrations were determined by digestion and sequential extraction. Comparison of results within the mobile fraction showed that after combustion, oxidizable elements bound to organic matter and sulfides in coal were mostly transformed into elements easily soluble in water or slightly acidic conditions and, hence, most readily bioaccumulative in the environment in ashes, mainly U, Cr, and As. Capacity of ashes as a source of mobile pollutants was quantified by combining sequential extraction and annual production. Just considering the easily soluble fraction, coal ashes could leach up to 839 tons of Al, 144 tons of Fe, 100 tons of Mn, 4.6 tons of Zn, 3.1 tons of Cr, 1.7 tons of As, 1.5 tons of Cu, 490 kg of U, and 20 kg of Pb every year. Bottom ashes are disposed of in landfill sites close to the plant. Fly ashes are recycled as construction material. Diagnostic processes do not consider checking for these highly mobile hazardous elements. Hence, uncontrolled dumping and use of these by-products may pose significant risks to environment and human health. © 2011 Elsevier Ltd. All rights reserved.


Silva L.F.O.,Centro Universitario Univates | Silva L.F.O.,Catarinense Institute of Environmental Research and Human Development IPADHC | Sampaio C.H.,Federal University of Rio Grande do Sul | Guedes A.,University of Porto | And 2 more authors.
Fuel | Year: 2012

A routine multianalytical methodology based on the combination of Optical Microscopy (OM) with instrumental microscopic techniques like Electron Microscope (HR-TEM and SEM) coupled to Energy Dispersive X-Ray Spectroscopy (EDS), Confocal Microscopy (CM) and Micro-Raman Spectroscopy (MRS) provides a powerful approach for the research of the mineralogical composition. Coals from different origins (five continents) and different mineralogical composition were selected for analysis. The analytical approach makes use of OM to select the different mineral phases associated to coal samples with subsequent use of the instrumental microscopic techniques on selected targets. The SEM/EDS, HR-TEM/EDS, and MRS analysis showed no significant differences in the chemical composition of the main minerals found associated to coal, such as oxides, sulphides, sulphates, silicates, carbonates, and others. The instrumental techniques provide fast, non-destructive and highly-selective analysis of both the whole coal and particle surfaces. Moreover, thermodynamic speciation through chemical modelling simulations gives the required information to confirm the stability of secondary minerals detected in the samples and helps to diagnose the potential environmental risks associated with weathering. © 2011 Elsevier Ltd. All rights reserved.


Cerqueira B.,University of Vigo | Vega F.A.,University of Vigo | Serra C.,University of Vigo | Silva L.F.O.,Catarinense Institute of Environmental Research and Human Development IPADHC | Andrade M.L.,University of Vigo
Journal of Hazardous Materials | Year: 2011

Relatively new techniques can help in determining the occurrence of mineral species and the distribution of contaminants on soil surfaces such as natural minerals and organic matter.The Bt horizon from an Endoleptic Luvisol was chosen because of its well-known sorption capability. The samples were contaminated with Cu 2+ and/or Pb 2+ and both sorption and desorption experiments were performed. The preferential distribution of the contaminant species ( 63Cu and 208Pb) to the main soil components and their associations were studied together with the effectiveness of the surface sorption and desorption processes. The results obtained were compared with non-contaminated samples as well as with previous results obtained by different analytical techniques and advanced statistical analysis. Pb 2+ competes favorably for the sorption sites in this soil, mainly in oxides and the clay fraction. Cu 2+ and Pb 2+ were mainly associated with hematite, gibbsite, vermiculite and chlorite.This study will serve as a basis for further scientific research on the soil retention of heavy metals. New techniques such as spectroscopic imaging and transmission electron microscopy make it possible to check which soil components retain heavy metals, thereby contributing to propose effective measures for the remediation of contaminated soil. © 2011 Elsevier B.V.


Silva L.F.O.,Centro Universitario Univates | Silva L.F.O.,Catarinense Institute of Environmental Research and Human Development IPADHC | DaBoit K.,Catarinense Institute of Environmental Research and Human Development IPADHC | Sampaio C.H.,Federal University of Rio Grande do Sul | And 6 more authors.
Science of the Total Environment | Year: 2012

Low-rank, high-mineral matter Bulgarian coals were studied using a variety of chemical, optical, and electron beam methods. The larger fly ash carbon phases include charred carbons in contrast to coked carbons present in the fly ashes of bituminous-coal-derived fly ashes. Nanoscale carbons include multi-walled carbon nanotubes (MWCNTs) encapsulating Hg, Se, and As, among other elements. In addition to the glass which dominates the fly ash, relatively coarse 'rock fragments', consisting of an unmelted to partially melted core surrounded by a glassy rim, are present in the fly ash. Nano-scale minerals can contain hazardous elements and, along with metal-bearing multiwalled nanotubes, can be a path for the entry of hazardous particles into the lungs and other organs. © 2011 Elsevier B.V.

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