Papers by Marzia Fantauzzi
Microporous and Mesoporous Materials, 2016
Analytical and bioanalytical chemistry, 2011
In this work, a multi-technical bulk and surface analytical approach was used to investigate the ... more In this work, a multi-technical bulk and surface analytical approach was used to investigate the bioleaching of a pyrite and arsenopyrite flotation concentrate with a mixed microflora mainly consisting of Acidithiobacillus ferrooxidans. X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and X-ray-induced Auger electron spectroscopy mineral surfaces investigations, along with inductively coupled plasma-atomic emission spectroscopy and carbon, hydrogen, nitrogen and sulphur determination (CHNS) analyses, were carried out prior and after bioleaching. The flotation concentrate was a mixture of pyrite (FeS 2 ) and arsenopyrite (FeAsS); after bioleaching, 95% of the initial content of pyrite and 85% of arsenopyrite were dissolved. The chemical state of the main elements (Fe, As and S) at the surface of the bioreactor feed particles and of the residue after bioleaching was investigated by X-ray photoelectron and X-ray excited Auger electron spectros-copy. After bioleaching, no signals of iron, arsenic and sulphur originating from pyrite and arsenopyrite were detected, confirming a strong oxidation and the dissolution of the particles. On the surfaces of the mineral residue particles, elemental sulphur as reaction intermediate of the leaching process and precipitated secondary phases (Fe-OOH and jarosite), together with adsorbed arsenates, was detected. Evidence of microbial cells adhesion at mineral surfaces was also produced: carbon and nitrogen were revealed by CHNS, and nitrogen was also detected on the bioleached surfaces by XPS. This was attributed to the deposition, on the mineral surfaces, of the remnants of a bio-film consisting of an extra-cellular polymer layer that had favoured the bacterial action.
L'arsenico è considerato tra i più pericolosi contaminanti ambientali. In natura è diffuso sulla ... more L'arsenico è considerato tra i più pericolosi contaminanti ambientali. In natura è diffuso sulla crosta terrestre con concentrazioni nei suoli che variano da 0,1 a 1000 mg Kg -1 . Nel pulviscolo atmosferico la concentrazione è compresa tra 50-400 mg Kg -1 , mentre nell'acqua di mare il livello medio di arsenico è di 2.6 ppb e nelle acque dolci è di circa 0.4 ppb [1]. Sono di grande attualità i fenomeni di inquinamento da arsenico in acque di falda in diverse regioni del Bangladesh e dell'India e che riguardano molte decine di milioni di persone . La concentrazione massima ammissibile stabilita dal DL 2 Febbraio 2001 n° 31 concernente la qualità delle acque destinate al consumo umano è di 10 µg/L. I valori di arsenico nelle acque in Italia ed in Sardegna sono spesso superiori a questo valore. La presenza dell'arsenico in un'acqua è legata a processi naturali di cessione degli elementi da parte dei minerali e sono di particolare interesse, rispetto all'inquinamento da arsenico, gli ambienti acidi di miniera. Il grado e le modalità con cui l'arsenico può essere rilasciato dipendono dalla stabilità e dalla reattività delle superfici dei minerali che contengono questo elemento in funzione dei parametri chimico-fisici del sistema considerato. I composti dell'arsenico mostrano tossicità diversa a seconda dello stato chimico: gli arseniti sono molto più tossici degli arseniati. E' quindi necessario mettere a punto un metodo che permetta di distinguere tra As (III) e As (V) sulle superfici dei minerali e che permetta la determinazione delle loro concentrazioni sia nell'acqua sia sulla superficie del minerale. Nell'ambito di uno studio intrapreso sulla reattività dei solfuri contenenti arsenico è stato messo a punto un metodo per l'analisi quantitativa dei film di spessore nanometrico presenti sulle superfici dei minerali esposti all'aria [3] e grazie all'applicazione del diagramma di Wagner o diagramma di stato chimico dell'arsenico si è nelle condizioni di distinguere tra i due stati di ossidazione . Obiettivo di questo lavoro è studiare il rilascio dell'arsenico da parte di un minerale solfuro combinando per la prima volta metodi di analisi di superficie, elettrochimici e analisi di soluzioni. Il minerale studiato è l'enargite Cu 3 AsS 4 , un solfuro di rame e arsenico piuttosto diffuso in Sardegna, in particolar modo nell'area mineraria di Furtei (Cagliari). Questo minerale è associato con altri minerali solfuri e con l'oro micro-implicato. Per poter studiare la reattività delle superfici di enargite isolando i parametri che ne possono influenzare la dissoluzione il nostro studio è partito da un'enargite estratta da una miniera peruviana perché piú pura dell'enargite di Furtei. I campioni di enargite sono stati immersi in una soluzione di acido solforico a pH 4 che simula una pioggia acida e quindi in soluzioni contenenti anche la coppia Fe 2+ /Fe 3+ . Le superfici appena sfaldate di campioni di minerale sono state analizzate con la spettroscopia di fotoelettroni a raggi X (XPS) prima e dopo l'esposizione alle soluzioni. In precedenza erano state condotte analisi su campioni di enargite sintetica e naturale, per ottenere i parametri necessari per adattare funzioni modello, costituite da una miscela di Gaussiane e Lorenziane, ai segnali sperimentali . Durante l'immersione sono state condotte misure elettrochimiche di potenziale di circuito aperto che non hanno mostrato variazioni in funzione del tempo: 0.00 mV dopo 1 giorno e 0.05 mV dopo 7 giorni. L'immersione dei campioni si è protratta per 24 ore e per 7 giorni. La successiva analisi XPS della superficie del minerale ha consentito di osservare le variazioni di
Analytical and Bioanalytical Chemistry, 2012
Three fibrous amphiboles that are not regulated as asbestos--two from Biancavilla (Sicily, Italy)... more Three fibrous amphiboles that are not regulated as asbestos--two from Biancavilla (Sicily, Italy) and one from Libby (MT, USA)--were studied in order to establish relationships between surface chemistry and surface reactivity. The three fibrous samples, plus one prismatic fluoro-edenite from Biancavilla that was used for comparison, were investigated by X-ray photoelectron spectroscopy (XPS) in order to obtain their quantitative surface compositions and to determine the chemical environment of the Fe in each case. In particular, the Fe 2p(3/2) peak was fitted and, for the first for these materials, the binding energies of Fe(II) oxide, Fe(III) oxide and Fe(III) oxyhydroxide were identified. Bulk chemistries and Fe oxidation states were obtained from previous studies for the samples from Biancavilla, and were investigated in the present work by electron microprobe (EMP) and (57)Fe Mössbauer spectroscopy (MS) for the sample from Libby. Comparison between surface and bulk data revealed that the sample with the lowest bulk Fe oxidation state was the one most affected by surface oxidation, while the samples with bulk highly-oxidised Fe were showing very high signal of Fe (III) oxy-hydroxide probably due to weathering. The surface reactivities of the fibrous amphiboles were investigated by measuring the production of the [DMPO, HO]• radical adduct using electron paramagnetic resonance (EPR) spectroscopy. Notably, significant chemical reactivity was observed; it was found to be comparable with--or, for the Libby sample, even higher than--that of fibrous tremolite (one of the six asbestos minerals). A positive linear correlation was observed when the production of HO• radical was plotted versus the Fe(II) content on the fibre surface. Data on fibrous tremolite obtained from previous studies were added to substantiate the correlation. These results provide evidence that Fe(II) at the fibre surface controls the production of radicals at the fibre surface. The observed relationship provides further confirmation that Fe topochemistry is strictly related to--though not solely responsible for--the toxicity of asbestos and other fibrous amphiboles that are not regulated as asbestos.
Analytical and Bioanalytical Chemistry, 2009
In this work, the microbe-mediated oxidative dissolution of enargite surfaces (Cu 3 AsS 4 ) was s... more In this work, the microbe-mediated oxidative dissolution of enargite surfaces (Cu 3 AsS 4 ) was studied on powdered samples exposed to 9K nutrient solution (pH 2.3) inoculated by Acidithiobacillus ferrooxidans initially adapted to arsenopyrite. These conditions simulate the acid mine environment. The redox potential of the inoculated solutions increased up to +0.72 V vs normal hydrogen electrode (NHE), indicating the increase of the Fe 3+ to Fe 2+ ratio, and correspondingly the pH decreased to values as low as 1.9. In the sterile 9K control, the redox potential and pH remained constant at +0.52 V NHE and 2.34, respectively. Solution analyses showed that in inoculated medium Cu and As dissolved stoichiometrically with a dissolution rate of about three to five times higher compared to the sterile control. For the first time, X-ray photoelectron spectroscopy (XPS) was carried out on the bioleached enargite powder with the aim of clarifying the role of the microorganisms in the dissolution process. XPS results provide evidence of the formation of a thin oxidized layer on the mineral surface. Nitrogen was also detected on the bioleached surfaces and was attributed to the presence of an extracellular polymer substance layer supporting a mechanism of bacteria attachment via the formation of a biofilm a few nanometers thick, commonly known as nanobiofilm.
Surface Science Spectra, 2002
X-ray photoelectron spectroscopy was used for characterizing the enargite surface. Freshly cleave... more X-ray photoelectron spectroscopy was used for characterizing the enargite surface. Freshly cleaved samples were analyzed at liquid nitrogen temperature. Enargite is a copper arsenic sulfide of formula it is used as a minor ore of copper. Enargite is a potential source of ...
Surface and Interface Analysis, 2007
... were characterized by optical and scanning electron microscopic observations as well as energ... more ... were characterized by optical and scanning electron microscopic observations as well as energy dispersive X-ray analysis, which showed them to be homogeneous and close to the stoichiometric composition17 (San Genaro mine enargite ... Smart RStC, Skinner WM, Gerson AR. ...
Surface and Interface Analysis, 2006
... to be in a chemical environment similar to that of arsenides or elemental arsenic, whereas ..... more ... to be in a chemical environment similar to that of arsenides or elemental arsenic, whereas ... averaged bulk compositions were estab-lished by energy dispersive X-ray analysis and in ... Three natural enargites, one from Peru (Museo di Mineralogia e Litologia, University of Florence ...
Microporous and Mesoporous Materials, 2015
Two samples of fibrous erionite from different localities of Oregon, USA were suspended in FeCl 2... more Two samples of fibrous erionite from different localities of Oregon, USA were suspended in FeCl 2 solutions at different concentrations, at pH ca. 5, in anaerobic conditions. Comparison between released and acquired charges under the form of Fe confirms that erionite binds Fe (II) by ion exchange with the extra framework (EF) cations, mainly Na. The Fe (II) binding process exhibited by both studied samples here investigated indicates a direct correlation between the extent of the ion-exchange process and the Fe (II) concentration of the solution used for fibres incubation. In the sample from Rome no further Fe (II) acquisition was observed for concentrations exceeding 500 mM FeCl 2 . XPS investigation revealed that, when comparing surface and bulk composition of the samples, no Fe enrichment of the fibre surface was observed. Moreover, the location of Fe (II) within the erionite cage has been devised by combining chemical and structural data. Results highlight that, for both samples, Fe (II) is fixed at the Ca3 site being six-fold coordinated to water molecules. The occurrence of Fe (II) within the erionite cage causes a gradual migration of the other EF cations and in addition, induces a small rearrangement of the water molecules positions. It is worth mentioning that, in Fe-loaded zeolites at rather low Fe content, the Fe sites with very low nuclearity, located in well-defined crystallographic positions, represent the active sites for the formation of reactive oxygen species. Therefore, identification of segregation of Fe (II) at Ca3, which is coupled with the high surface area of erionite, provides very important information for the understanding of the molecular mechanism/s inducing its strong carcinogenicity.
J. Mater. Chem. A, 2014
ABSTRACT Zinc oxide/ and iron oxide/SBA-15 composites were synthesized by innovative Two-Solvents... more ABSTRACT Zinc oxide/ and iron oxide/SBA-15 composites were synthesized by innovative Two-Solvents procedure and tested as sorbents for the mid-temperature (300 °C) removal of hydrogen sulphide, and compared with a commercial unsupported ZnO sorbent. The sulphur retention capacity results showed the superior performance of the iron oxide/SBA-15 composite (401 mg S/g Fe2O3) in comparison with the zinc oxide/SBA-15 one (53 mg S/g ZnO), both these sorbents being much more efficient than the commercial sorbent (6 mg S/g ZnO). The different sorption behaviour was discussed in terms of the nature of the nanocomposites where: (i) the mesostructure of the support is retained, surface area and pore volume being quite high; (ii) the zinc oxide phase is incorporated inside the SBA-15 channels as a thin amorphous homogeneous layer while the iron oxide is dispersed in form of small maghemite crystallites; (iii) significant interactions occur between the silica matrix and the zinc oxide phase. Remarkable differences in the regeneration behaviour of the exhaust sorbents were revealed by temperature-programmed experiments under oxidizing atmoi
Journal of Electron Spectroscopy and Related Phenomena, 2014
The analytical characterization of surfaces of sulfur-bearing samples that present sulfides, poly... more The analytical characterization of surfaces of sulfur-bearing samples that present sulfides, polysulfides and/or elemental sulfur as reaction products can be difficult by simply relying on the binding energy of the S2p X-ray photoelectron signals, due to the small chemical shifts. In such cases the Auger parameter concept can be used to distinguish among different chemical states, but this requires a model to curve fit complex Auger SKLL signals in order to resolve the contributions arising from sulfur in different chemical states on the surface. With this scope a detailed X-ray photoelectron spectroscopy (XPS) and X-ray induced Auger electron spectroscopy (XAES) surface analytical study of the group IA sulfates is presented in this paper. Sulfates were chosen as model compounds for curve fitting the X-ray induced SKLL spectra since in these compounds sulfur is present in a unique chemical state.
Surface Science Spectra, 2002
X-ray photoelectron spectroscopy was used for characterizing the enargite surface. Freshly cleave... more X-ray photoelectron spectroscopy was used for characterizing the enargite surface. Freshly cleaved samples were analyzed at liquid nitrogen temperature. Enargite is a copper arsenic sulfide of formula it is used as a minor ore of copper. Enargite is a potential source of ...
ACS applied materials & interfaces, Jan 23, 2015
A chronoamperometric method has been applied for the growth of a surface coating on AZ31B magnesi... more A chronoamperometric method has been applied for the growth of a surface coating on AZ31B magnesium alloy, using the imidazolium alkylphosphonate room-temperature ionic liquid 1-ethyl-3-methylimidazolium ethylphosphonate ([EMIM][EtPO3H]) as electrolyte. A surface coating layer is obtained after 4 hours under a constant voltage bias of -0.8V with respect to the standard electrode. The coating nucleation and growth process correlates well with a 3D progressive mechanism. XPS analysis of [EMIM][EtPO3H] shows new P2p and O1s peaks after its use as electrolyte, as a consequence of reaction between the phosphonate anion and the magnesium substrate. Angle-resolved XPS (ARXPS) analysis of [EMIM][EtPO3H] did not show any change in the composition of the surface before and after chronoamperometry, since the sampling depth (1.5 nm at the highest emission angle) is larger than the cation and anion sizes (ca. 7Å and 5 Å, respectively). Characterization of the coating was made by SEM, FIB-SEM, ED...
RSC Adv., 2015
ABSTRACT The paper describes synthesis and characterization of novel TiO2-Metal Hexacyanometallat... more ABSTRACT The paper describes synthesis and characterization of novel TiO2-Metal Hexacyanometallates (MHCMs) composite materials. The starting material, TiO2, was modified by addition of cobalt-hexacyanoferrate (CoHCF) or iron-hexacyanocobaltate (FeHCC) at various concentrations. The resulting composites were charcterized as follows: cyclic voltammetry (CV) followed the formation of TiO2-MHCM clusters, TEM micrographs studied their morphology, XAS and XPS data indicated that MHCM bonds to TiO2 through the the nitrogen atom of its -CN group and modifies the environment of Ti compared to that of pure anatase. As expected, and confirmed by UV-Vis and XP-valence band data, the electronic properties of TiO2 were substantially modified: the edge in the composite materials shifted by about 2.0 eV relative to TiO2.
Chemical Geology, 2015
ABSTRACT Non-occupational, environmental and unintentional exposure to fibrous tremolite, one of ... more ABSTRACT Non-occupational, environmental and unintentional exposure to fibrous tremolite, one of the most widespread naturally occurring asbestos, represents a potentially significant geological risk in several parts of the world. The toxicity of amphibole asbestos is commonly related to iron content and oxidation state, but information available on surface iron topochemistry and amphibole alteration mechanism is still rather poor. With the aim to shed a light on this mechanism, two tremolite samples, one from Italy (Castelluccio) and one from USA (Maryland), immersed in a buffer solution (pH 7.4) with H2O2 were characterized by a multi-technique approach. X-ray photoelectron spectroscopy (XPS) and high resolution–transmission electron microscopy (HR-TEM) were used to investigate the surface chemistry of the incubated samples and to detect structural modifications of the fibres, while inductively coupled plasma optical emission spectrometry (ICP-OES) was used to determine the concentration of dissolved elements.
ABSTRACT Samples of particulate matter (PM) collected in the city of Milan during wintertime were... more ABSTRACT Samples of particulate matter (PM) collected in the city of Milan during wintertime were analyzed by X-ray photoelectron spectroscopy (XPS), thermal optical transmittance (TOT), ionic chromatography (IC) and X-ray fluorescence (XRF) in order to compare quantitative bulk analysis and surface analysis. In particular, the analysis of surface carbon is here presented following a new approach for the C1s curve fitting aiming this work to prove the capability of XPS to discriminate among elemental carbon (EC) and organic carbon (OC) and to quantify the carbon-based compounds that might be present in the PM. Since surface of urban PM is found to be rich in carbon it is important to be able to distinguish between the different species. XPS results indicate that aromatic and aliphatic species are adsorbed on the PM surface. Higher concentrations of (EC) are present in the bulk. Also nitrogen and sulfur were detected on the surfaces and a qualitative and quantitative analysis is provided. Surface concentration of sulfate ion is equal to that found by bulk analysis; moreover surface analysis shows an additional signal due to organic sulfur not detectable by the other methods. Surface appears to be also enriched in nitrogen.
Analytical and bioanalytical chemistry, 2010
Asbestos fibers are an important cause of serious health problems and respiratory diseases. The p... more Asbestos fibers are an important cause of serious health problems and respiratory diseases. The presence, structural coordination, and oxidation state of iron at the fiber surface are potentially important for the biological effects of asbestos because iron can catalyze the Haber-Weiss reaction, generating the reactive oxygen species *OH. Literature results indicate that the surface concentration of Fe(III) may play an important role in fiber-related radical formation. Amphibole asbestos were analyzed by X-ray photoelectron spectroscopy (XPS) and Mössbauer spectroscopy, with the aim of determining the surface vs. bulk Fe(III)/Fe(tot) ratios. A standard reference asbestos (Union Internationale Contre le Cancer crocidolite from South Africa) and three fibrous tremolite samples (from Italy and USA) were investigated. In addition to the Mössbauer spectroscopy study of bulk Fe(III)/Fe(tot) ratios, much work was dedicated to the interpretation of the XPS Fe2p signal and to the quantificat...
Geochimica et Cosmochimica Acta, 2014
European Journal of Mineralogy, 2007
Enargite, a copper arsenic sulfide having the formula Cu 3 AsS 4, is a source of arsenic and may ... more Enargite, a copper arsenic sulfide having the formula Cu 3 AsS 4, is a source of arsenic and may cause environmental problems owing to the release of toxic elements upon oxidation, especially in acid mine effluents. In this work the oxidative dissolution of enargite has ...
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Papers by Marzia Fantauzzi