1,720,984 research outputs found
Evaluation of a FTIR data pretreatment method for Principal Component Analysis applied to archaeological ceramics
No full textThe aim of thiswork is to explore the potential of Fourier Transform Infrared (FTIR) spectroscopy and chemometric
analysis as a tool to differentiate ceramics having different provenance. We propose a new spectral FTIR data
pretreatment method for Principal Component Analysis (PCA) as the selection of a proper algorithm and its
application could play an important role in minimizing the manipulation of data. We consider the data in the
spectral region between 400 and 1500 cm−1, since this range takes into account the contribution of the
fingerprints of inorganic compounds (below 1000 cm−1), and the carbonate absorption band at about
1400 cm−1. Normalization of FTIR data between 0 and 1 has been followed by the calculation of the second
derivative, without the smoothing of data; thus resulting in minimizing the manipulation of experimental data
and reducing the influence on PCA. The proposed procedure has been applied to ancient potteries from Khirbet
al-Batrawy (Jordan), Motya (Trapani, Italy) and the Palatine Hill (Rome, Italy). A series of elaborations with PCA,
step by step, is proposed to reduce the number of variables (from more than 1000 to ~200). This allowed the
identification of the discriminating vibrational bands for each group obtained by PCA to explain the separation
of samples on the basis of their mineralogical composition. The application of the statistical data processing
proposed here allowed for the discrimination of different ceramic productions
Recycling of granite scraps in Sardinia by innovative and economically-viable extraction technology in a context of circular economy
No full textItaly is the world’s second-largest feldspar producer (3 million tons/year, 22% of total) and the world biggest importer (22% of global world trades) (European Commission). Since the strong demand is rapidly depleting the proven reserves in EU Member States, the EU ceramics sector is increasingly dependent on feldspar imports from Turkey. In the future, it will be necessary to find additional sources of feldspar or to
further increase inter-continental transport. The ever increasing demand for feldspar, for ceramics, glass and other industrial uses, therefore, requires the extraction of granite and considerable international trade flows. At present, Buddussò-Alà dei Sardi (Sardinia Region-Italy) is the most important granite production area in Italy, with 66 authorised quarries (12 active), 70% of regional granite production and more than 50% of total Italian production. However, granite mining activities cause serious environmental problems. In Italy, every year
350.000-400.000 m3 of raw granite are extracted (Lucarini et al, 2020) generating the same quantity of waste.
Feldspar production and trade generate large amounts of pollutant and greenhouse gas emissions, due either to the energy consumption of mining activities or from the transport of the finished product from the exporting countries (mainly Turkey and China). The areas where quarries are active suffer from landscape degradation, due to incomplete compliance or non-compliance with quarry recovery plans, considering that opening new quarries is cheaper than moving large amounts of waste. Finally, granite mining accounts for huge amounts of
soil consumption, as it requires large areas in which the quarry waste accumulates.
The LIFE REGS II project (LIFE19 ENV/IT/000373 LIFE REGS II) aims at demonstrating an innovative and economically-viable extraction technology to produce feldspars, of the same quality to those obtained from virgin raw material, using granite scraps rather than virgin raw material. This will reduce demand for feldspar from environmentally-damaging granite mining operations as well as to minimize the soil consumption and to
boost the awareness about the importance of recycling granite scraps. The project will contribute to the implementation of the EU Action Plan for the Circular Economy, the Roadmap for a Resource Efficient Europe, and Directive 2006/21/EC on the management of waste from extractive industries
Recycling of eggshell waste into low-cost adsorbent for Ni removal from wastewater
No full textThe disposal of about 8 million ton/year of eggshell waste produced worldwide is an environmentally challenging issue. However, this waste can be converted to new materials useful for several industrial applications. In this study, hydroxyapatite was synthesized from eggshell waste and used as adsorbent for Ni2+ removal from aqueous solutions. Eggshell-derived hydroxyapatite was characterized using X-ray diffraction, scanning electron microscopy with the energy dispersion spectrum analysis and Fourier transform infrared spectroscopy. Batch experiments were conducted to investigate the effects of contact time and initial Ni2+ concentration on the adsorption process. Adsorption equilibrium was achieved within 80 min. The kinetics of the adsorption process was studied applying pseudo-first-order, pseudosecond-order and intraparticle diffusion kinetics models. The kinetics study showed that the pseudosecond-order kinetic model described well the adsorption process with high correlation coefficient. The maximum Ni2+ adsorption capacity was found to be 109 mg g-1 which is generally higher than other waste-derived adsorbents. The adsorption of Ni2+ on eggshell-derived hydroxyapatite was well fitted by the Langmuir equation as compared to Freundlich, Temkin and Dubinin-Radushkevic isotherm models. The removal mechanism of Ni2+ by eggshell-derived hydroxyapatite could involve ion exchange with Ca2+ and dissolution/precipitation of the starting hydroxyapatite resulting in the formation of a Ni-bearing phosphate. The results of the present study showed that hydroxyapatite synthesized from eggshell waste represents an excellent low-cost adsorbent for treatment of Ni2+ contaminated waters
Response of benthic foraminifera to natural stress: a case-study from the active volcanic area of Azores Islands
No full textThe present study shows the preliminary micropaleontological results carried out on grab and box corer samples collected during the Eurofleet marine geological survey in the Terceira offshore (Azores Archipelago, Portugal) occurred in September 2011. A main WNW-ESE oriented fissural eruptive zone crosses the Terceira Island extending down to the sea, along the Serreta Ridge. An intermediate-depth submarine eruption occurred in 1998-2001 producing a consistent amount of volcanic materials scattered around the vent.
Benthic foraminiferal assemblages were studied in order to obtain an ecological characterization of sea-floor and water masses in natural stressed environments like volcanic area of the Azores Islands, after the last volcanic eruption. The samples collected in a bathymetrical interval ranging between 260 and 410 m water depth, are constituted of blackish, sand-sized glass shards, in which highly vesicular to scoriaceous clasts prevail on fluidal striated fragments. All samples were stained with Rose Bengal to distinguish living and dead assemblages. Diversity index (α-Fisher index), Faunal density and Foraminiferal Abnormality Index (FAI) were calculated to define the structure of the assemblage and the degree of environmental stress. The preliminary results show that the living taxa number ranges from 18 to 43 while the α-Fisher index shows constant values around 15-16. The living benthic assemblage is dominated by deep infaunal species like Angulogerina angulosa, and Bolivina spp. Angulogerina angulosa is considered in some cases epifaunal and in other ones infaunal species. In this study, the record of living specimens of A. angulosa along the whole box-corer, almost until 10 cm depth, suggests a certain capability of this taxon to migrate into the bottom sediments. Subordinately, epifaunal (Lenticulina spp., Eherenbergina bradyi, Stomatorbina concentrica, Quinqueloculina seminulum) and agglutinated (Aplophragmoides canariensis, Ammoglobigerina globigeriniformis, Spiroplectinella wrightii, Textularia spp., Eggerelloides scabrus) species are recorded too. Significant frequencies of specimens, showing signs of decalcification of the tests, were found. Similar test alterations, due to hydrothermal fluids, were recorded in foraminiferal specimens coming from other volcanic bottoms (Aeolian Arc, Tyrrhenian Sea).The dominance of living and dead A. angulosa specimens allows to consider this species as opportunistic pioneer taxon able to colonize stressed environments. In fact, the highest values of FAI (>2), recorded in the most samples, indicate a persisting environmental stress due to the occurrence of repeated volcanic events. Angulogerina angulosa and Bolivina spp. are the species showing more abundant deformed specimens. The test abnormalities consist mainly of irregular development of chambers and aberrant tests
The late Variscan ferroan granite magmatism of southern Sardinia: inferences from Mo metallogenesis
Full text linkForaminiferal assemblages in active volcanic area of Azores Islands
No full textThe present study shows the preliminary micropaleontological results carried out on grab and box corer
samples collected during a marine geological survey in the Terceira offshore (Azores Archipelago, Portugal)
occurred in September 2011, in the framework of the Eurofleet program. This multidisciplinary project aims to
reconstruct high-resolution morpho-bathymetry offshore Terceira Island and to define the evolution history of
the Terceira volcanic edifice. A main WNW-ESE oriented fissural zone, characterized by the alignment of
scoria cones and eruptive fractures, crosses the island extending down to the sea, along the Serreta Ridge.
An intermediate-depth submarine eruption occurred in 1998-2001 producing a consistent amount of volcanic
materials (lava balloons, highly vesciculated basaltic scoria, lapilli, etc.) scattered around the vent.
In this study benthic and planktic foraminiferal assemblages were studied in order to obtain an ecological
characterization of sea-floor and water masses in natural stressed environments like volcanic area of the
Azores Islands, after the last volcanic eruption. The samples collected in a bathymetrical interval ranging
between 260 and 410 m water depth, are constituted of blackish, sand-sized glass shards, likely originating
by volcanic explosive events, in which highly vesicular to scoriaceous clasts prevail on fluidal striated
fragments. All samples were stained with Rose Bengal to distinguish living and dead assemblages. Diversity
index (α-Fisher index), Faunal density and Foraminiferal Abnormality Index (FAI) were calculated to define
the structure of the assemblage and the degree of environmental stress. The preliminary results show that in
the most part of the samples, the living taxa number ranges from 18 to 43 while the α-Fisher index shows
constant values around 15-16. The living benthic assemblage (Rose Bengal stained specimens) is
dominated by deep infaunal species like Angulogerina angulosa, and Bolivina spp. Angulogerina angulosa is
considered in some cases epifaunal and in other ones infaunal species. In this study, the record of living
specimens of A. angulosa along the whole box-corer, almost until 10 cm depth, suggests a certain capability
of this taxon to migrate into the bottom sediments. Probably this species is rather mobile and able to shift its
microhabitat from infaunal to epifaunal, somehow reflecting stress forcing. Subordinately, epifaunal
(Lenticulina spp., Eherenbergina bradyi, Stomatorbina concentrica, Quinqueloculina seminulum) and
agglutinated (Aplophragmoides canariensis, Ammoglobigerina globigeriniformis, Spiroplectinella wrightii,
Textularia spp., Eggerelloides scabrus) species are recorded too. Moreover, small sized specimens of
Anomalinoides spp. and Miliolinella subrotunda seem to prefer a way of life attached on volcanic shards.
Also some agglutinated foraminifers (mainly Aplophragmoides canariensis) were found clinged to glass
fragments. Their test are constituted by exclusively glass grains reflecting the compositions of the bottom.
Significant frequencies of specimens, showing signs of decalcification of the tests, were found too. Similar
test alterations, due to hydrothermal fluids, were recorded in foraminiferal specimens coming from other
volcanic bottoms (Aeolian Arc, Tyrrhenian Sea).The dominance of living and dead A. angulosa specimens
allows to consider this species as opportunistic pioneer taxon able to colonize stressed environments. In fact,
the highest values of FAI (>2), recorded in the most samples, indicate a persisting environmental stress due
to the occurrence of repeated volcanic events in the past years. Moreover A. angulosa and Bolivina spp. are
the species showing more abundant deformed specimens. The test abnormalities consist mainly of irregular
development of chambers and aberrant tests (e.g., double apertures).
The total planktic foraminiferal association reflects a clear seasonality. In fact, the living planktic assemblage
is characterized by temperate-warm taxa like Globorotalia inflata, Globorotalia truncatulinoides (left),
Globorotalia hirsuta, Globigerinoides spp. while cold affinity taxa as Globigerina bulloides and Turborotalita
quinqueloba are frequent mainly in the dead assemblage. Plankton seems to be not affected by the Azores
Front-Current System, that is centred at 34° N, south of Azores Islands
A Late Variscan tin province associated to the ilmenite-series granites of the Sardinian Batholith (Italy): The Sn and Mo mineralisation around the Monte Linas ferroan granite
No full textThe characterisation of the late Variscan intrusion of Monte Linas (southern Sardinia) allowed to firstly study some Sn-bearing ores of this area and their relationships with the surrounding intrusives. The Monte Linas pluton was emplaced at ca. 290 Ma at a shallow crustal level between allochthonous units and the foreland of the Sardinian Variscan belt. The pluton emplaced in a post-collisional regime into a previously exhumed low-grade basement, forming a coarse-grained monzogranite that is capped by an almost continuous sub-horizontal sheet of fine-grained rocks. The rocks within the pluton are ferroan F-bearing granites, belonging to the ilmenite-series. They have alumina saturation index values indicative of sub-aluminous to slightly peraluminous granitoids, as also indicated by the chemical composition of biotite within the pluton. The new data of this study indicate that the Monte Linas pluton formed from water-undersaturated magmas under low-fO2 conditions at temperatures > 850 °C. The later stages of magmatism were characterised by boiling and fluid expulsion at confining pressures of < 1 kbar, producing fayalite-bearing pegmatites, miarolitic facies and greisening. A wide variety of mineral deposits are associated with the Monte Linas pluton, including different types of Sn-bearing and Mo-bearing ores. Sn-bearing ores are represented by 1) Sn–As and Sn–Pb–Zn–Cu veins, and 2) “wrigglite” skarn Fe-Zn-Sn ores. Field and analytical studies, including fluid inclusion analyses, EMPA and SEM-EDS, allow to refer these deposits to the evolution of initial highly saline, hypothermal magmatic fluids, as confirmed by parageneses and fluid inclusion analyses of cassiterite in veins, which provide evidence of polyphase processes that started at temperatures close to 400 °C. The hydrothermal systems were initially characterised by low-fO2 and high-chlorine solutions that mobilised Sn and underwent rapid changes in physicochemical conditions that led to the deposition of cassiterite. In the “wrigglite” F-rich genetic environment, a role of fluoride as complexing agent for Sn can be inferred. The Monte Linas pluton is also characterised by Mo deposits, not typical in ilmenite series granites; they occur both as greisens and veins. Mo was mobilized as a result of rapid increases in fO2 within the magmatic system, and precipitated in a fS2-rich environment nearby the contact between the intrusion and the surrounding country rocks. The variety of Sn mineralising events around the Monte Linas pluton confirms the role of physicochemical characters of magmas and of magmatic processes in the genesis of tin deposits. The occurrence in southern Sardinia of a wide suite of ilmenite-series ferroan granites emplaced in similar geological contexts allows to consider the idea of a low-grade tin province and opens the way to further explorations
Preliminary petrographic and volcanological study of “Punta Karuscia-Punta Spadillo” submerged area, Pantelleria Island (Strait of Sicily)
No full textThe Pantelleria Island (Mediterranean Sea, Italy) is located in the Sicily Channel Rift Zone (SCRZ) and represents the emergent tip of an underwater volcano complex with 72% lying below sea level, down to a depth of about 1200 m. Its origin is linked to the Pantelleria graben, one of the three main tectonic depressions of the NW-SE trending extensional area SCRZ. The rifting process is active since the Late Miocene and was accompanied by a widespread volcanic activity mainly concentrated on Pantelleria and Linosa islands.
The volcanic history of Pantelleria started before 320 ka BP and the volcanic activity was characterized by large explosive events, sometimes followed by caldera collapses, alternated to mild eruptions. The last caldera collapse event (45-50 ka BP) followed the major eruption emplacing the Green Tuff ignimbrite. While the post Green Tuff activity has been reconstructed in detail and subdivided into six silicic cycles (pantellerite to trachytes), interposed with mildly alkaline basalts in the NW sector of the island, the volcanic history of Pantelleria before 50 ka BP is poorly known due to the paucity of rock outcrops.
High resolution multibeam bathymetry data (Bosman et al., 2011) show how the volcanic Island rises from a gently sloping seafloor in the NW and in the SE sectors, while is bounded by steep flanks and rimmed by a very narrow or absent shelf on the NW and SW sectors. The definition of the extents and characters of submarine portions of the edifice allow a better comprehension of their structure (Conte et al., 2014). Thus, aimed to provide a contribution in the reconstruction of the evolution of the Pantelleria volcanism, thirteen volcanic rocks were collected in shallow-water, offshore the N-W Pantelleria by SCUBA diving. The rocky outcrops were identified by high resolution multibeam bathymetry data in very shallow water. Preliminary data indicate that the collected samples are variably porphyritic lavas (P.I. = 5-20 % vol) classified as pantellerites and basalt/hawaiites, which features are correlated with those of the emerged area, allowing to outline a preliminary volcanological-map of the submerged sector “Punta Karuscia-Punta Spadillo” of Pantelleria Island in shallow water
Experimental investigation of CO2-rich fluids production in a geothermal area: The Mt Amiata (Tuscany, Italy) case study
No full textEco-sustainable solutions to transform quarry waste of granite rocks into resources for the ceramic and glass industry.
No full textRaw materials are essential for the sustainable development of modern societies. Access to and cost-effectiveness of mineral raw materials are critical to the smooth functioning of the EU economy. The growing demand for raw materials raises increasing concerns about mineral resources. Feldspars along with quartz, the main components of granitoid rocks, are widely used in ceramic and glass industry. The need to meet the demands of the ceramic industry has stimulated research and development of new ceramic flows in granite complexes.
Italy is the world’s second-largest feldspar producer (22% of total) and the world biggest importer (22% of global world trades) (European Commission). Since the strong demand is rapidly depleting the proven reserves in EU Member States, the EU ceramics sector is increasingly dependent on feldspar imports from Turkey. Thus, it is necessary to find additional sources of feldspar or to further increase inter-continental transport. At present, Buddusò-Alà dei Sardi (Sardinia-Italy) is the most important granite production area in Italy. However, granite mining activities cause serious environmental problems. Feldspar production and trade generate large amounts of pollutant and greenhouse gas emissions, due either to the energy consumption of mining activities or the transport of the finished product from the exporting countries. The areas where quarries are active suffer from landscape degradation, due to incomplete compliance or non-compliance with quarry recovery plans, considering that opening new quarries is cheaper than moving large amounts of waste. Finally, granite mining accounts for huge amounts of soil consumption, as it requires large areas in which the quarry waste accumulates.
The LIFE REGS II project (LIFE19 ENV/IT/000373 LIFE REGS II) aims at demonstrating an innovative and economically-viable extraction technology to produce feldspars, of the same quality to those obtained from virgin raw material, using granite scraps. This will reduce demand for feldspar from environmentally-damaging granite mining operations as well as to minimize the soil consumption and to boost the awareness about the importance of recycling granite scraps.
To this respect, samples of the granite scraps accumulated in 18 landfills located in the Buddusò-Alà dei Sardi granite quarries have been analyzed for their mineral texture and composition. Modal variability of the main mineral constituents (quartz+plagioclase±potassium-feldspar+biotite/chlorite) allowed to distinguish three main groups characterized by different ratios of feldspars/mafic phases with the exception of samples from a specific landfill that display an increase in the plagioclase at the expense of potassium-feldspar+quartz along with an increase in epidote at the expense of biotite/chlorite.
Texturally potassium-feldspar occasionally occurs as microcline perthite while plagioclase is always affected by extensive alteration resulting in a variety of textural intergrowths of neoformed minerals. Such features are reflected in the inter/intra-crystalline compositional variations in terms of feldspar end-members and in the type of the alteration products. This provides the elements for a first estimate of the technological properties of felsdpars, allowing to recognize the material stored in the 18 landfills qualitatively better for commercial purpose, and to experimentally identify the most effective methods of physical treatments to enrich and extract feldspars useful for industrial uses
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