1,721,015 research outputs found
Scrano, L., Pallara, M., Buccione, R., Mongelli, G., Bufo, S.A., Laviano, R., 2023. Characterization of Natural and Modified Clay Used for a Filtration System Aiming at the Removal of Contaminants from Surface Water. In: Çiner, A., et al. Recent Research on Environmental Earth Sciences, Geomorphology, Soil Science, Paleoclimate, and Karst. MedGU 2021. Advances in Science, Technology & Innovation. Springer, Cham.
No full textFluorescenza di raggi X
No full textLa tecnica di analisi spettrochimiche per fluorescenza di raggi X (FRX)
permette di ottenere le analisi chimiche, in elementi o in ossidi; tali analisi
possono essere espresse come atomi per cento o come atomi in peso per
cento. Spesso, per consuetudine, soprattutto nelle analisi di minerali e rocce,
le analisi vengono espresse come ossidi, legando stechiometricamente
l’ossigeno al catione dosato.
La FRX è considerata una tecnica distruttiva perché normalmente il
campione deve essere macinato e successivamente trattato con leganti
organici o con altri componenti per poterne ottenere un disco su cui effettuare
le misure: difficilmente si potrà recuperare il campione originale,
una volta ottenuto il provino per le analisi FRX. Cosa importante è che lo
stesso provino lo si potrà rianalizzare, con un altro spettrometro FRX o
anche con altra strumentazione analitica come ad esempio la microscopia
elettronica a scansione, anche a distanza di molti anni, purché esso sia
stato ben conservato.
Nel seguito saranno descritti i casi in cui è possibile utilizzare questa
metodica anche in modo assolutamente non distruttivo.
La quantità di campione necessaria per un’analisi chimica mediante FRX
varia, a seconda del risultato qualitativo o quantitativo che si voglia ottenere
ed a seconda della metodica e della strumentazione utilizzata, da poche decine
di milligrammi (circa 40 mg, Acquafredda et al., 2018) fino a circa 12 g.
I campioni che si possono analizzare in FRX sono i più disparati, dalle
rocce, ai minerali, ai manufatti industriali, ai materiali da costruzione, ai
metalli, alle vernici, ecc. In pratica si può analizzare quasi tutto quello che
è una sostanza solida ed in molti casi anche sostanze liquide o gelatinose.
La preparazione del campione dipenderà dalla metodica analitica che
si vorrà utilizzare; in alcune occasioni, come per le analisi non distruttive,
il campione potrà essere analizzato senza alcun trattamento preventivo
o addirittura senza essere spostato dalla sua sede naturale. Quest’ultima
possibilità apre un campo molto vasto di applicazioni, in special modo in
ambito forense o dei Beni Culturali, lì dove potrebbe essere necessario
analizzare campioni non rimovibili per motivi legali o difficilmente trasportabili
perché di grandi dimensioni; stesso discorso vale per la caratterizzazione
di oggetti preziosi la cui parziale distruzione diminuirebbe
notevolmente il valore dell’oggetto da analizzare.
Negli ultimi anni, l’utilizzo di spettrometri FRX portatili, sempre più
spesso consente di rilevare la presenza: sul territorio di inquinanti, le cui
analisi puntuali potranno essere successivamente confermate da opportuni
campionamenti, cui seguiranno più accurate misure in laboratori qualificati
al rilascio di certificati di analisi
Medieval Islamic type pottery from Siponto (Italy): an integrated physical-chemical and mineralogical investigation
No full textPhysical–chemical and morpho-mineralogical characterizations were performed on siliceous paste
fragments from the archaeological site at Siponto (Foggia, Italy). Analytical investigations, by optical
and scanning electron microscopy, powder x-ray diffraction, x-ray fluorescence and atomic spectroscopy,
were carried out on ceramic bodies, coatings and decorations in order to outline the technological features
and define the nature of coatings and pigments. The fragments, characterized by a siliceous paste bulk,
true stonepaste type,with alkali–lime or lead–alkali glaze, sometimes coloured by Cu andMn compounds
and decorated by incision, recall the ceramic production technologies typical of the Egyptian and the
Syrian–Palestinian areas. The discovery of these fragments and the results of the investigations carried
out prove the existence of extensive cultural exchanges between Apulia and the Middle East during the
Middle Ages. This research provides extremely valuable input for the evaluation of the historical and
artistic evolution of the relationship between different cultures, highlighting the relevance of scientific
investigations also in archaeological fields other than provenance and dating
The geochemistry and the palaeo-environmental significance of Upper Cretaceous clay-rich beds from the Peri-Adriatic Apulia Carbonate Platform, southern Italy
No full textChemical-mineralogical characterisation of clay sediments around Ferrara (Italy): a tool for an environmental analysis
No full textThe content of heavy metals in water and soil is a key parameter for evaluating the geochemical vulnerability of an ecosystem. These elements display a limited solubility and are easily trapped and adsorbed by phyllosilicate minerals; they are thus preferentially partitioned in the fine fraction of sediments. In this light, an analysis of recent river sediments gives information on possible water pollution, and more in general on the related ecosystem. We therefore investigated the chemical-mineralogical features of clay sediments outcropping around the town of Ferrara, paying particular attention to their fine fraction (grain size180 ppm; Ni>100 ppm) and low (Cr1); on the other hand, the high-Cr samples have a coarser grain size, and a lower abundance of clay minerals in which chlorite (Mg-rich chlorite in this group of samples) predominates over smectite+mixed layers (Sm+ML/Chl<1). These two distinct groups of samples are ascribed to different sources: high-Cr lithologies are related to the sedimentary contribution of the Po river, whereas low-Cr sediments plausibly derive from small rivers of Apennine origin (e.g. the Reno river). Within the high-Cr group, concentrations of Ni and Cr tend to be higher than those indicated by the current environmental Italian legislation. However, in the study-case presented here, the detected high heavy-metal concentrations are not related to urban-industrial-agricultural activities, but instead appear to be typical of the original lithologies.An integration of similar scientific contributions would be useful to set up a geochemical-mineralogical database as a first step toward the preparation of more complete thematic maps. These would provide information relative to the behaviour (e.g. distribution and abundance) of chemical elements within the different geochemical spheres, and would be useful for recognising and interpreting possible geochemical anomalies induced by pollution processes
South-Italian Late Bronze Age pottery production: raw materials and paste preparation at Madonna del Petto (Barletta, Bari)
No full textLate Roman cooking pottery from the Tavoliere area (Southern Italy): raw materials and technological aspects
No full textGeochemistry and mineralogy as indicators of parental affinity for Cenozoic Bentonites: a case study from S. Croce di Magliano (southern Apennines, Italy)
No full textThe major and trace element contents and mineralogical composition of Cenozoic
bentonites from the southern Apennines (Italy) have been determined, for the whole-rocks and the
<2 ~tm size-fractions, in order to constrain parental affinities. The main mineralogical and chemical
differences have been recognized in eleven samples allowing them to be grouped into two distinct
subsets. The differences are based on smectite abundance, occurrence or lack of detrital clay phases,
different contents of Ti, Fe, Mn, K, P, Rb, Sc, V, Cr and Ni and differences in the Eu/Eu* and Ti/AI
elemental ratios. These ratios indicate an affinity for felsic volcanics for the subset showing high
smectite contents. The low smectite subset shows, instead, an affinity for Cretaceous-Oligocene
southern Apennine shales. A similar result is obtained using the La-Th-Sc and Th-Sc-Zr/10 diagrams.
We suggest that during the deposition of the southern Apennine shales, episodic volcanic events took
place. These were associated with the suture stage of the Tethyan ocean that promoted accumulation
of felsic ash in the related basin and the diagenetic alteration of these materials produced bentonitic
layers interbedded with shales
Clay sediments in the area surrounding Ferrara (Italy): a contribution for the environmental monitoring
No full textPlinius (supplemento italiano all¿European Journal of Mineralogy
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