We analyzed samples of antigorite, lizardite and fibrous chrysotile, three representative minerals of the serpentine group, to determine their chemical and structural properties, and their FT-Raman spectra. The low-frequency region of the spectrum (1200-200 cm -1 ), which corresponds to the lattice-vibration modes, was then analyzed, and the observed bands attributed, on the basis of our results. Raman spectroscopy thus proves useful in identifying the three mineral species, despite their strong similarities in structure and chemical composition. The symmetric stretching modes of the Si-O b -Si linkages vibrate at different frequencies in chrysotile and antigorite, whereas chrysotile and lizardite can easily be identified by analyzing the vibrations of the OH-Mg-OH groups and the bands in the range 550-500 cm -1 .

Raman spectroscopy was assessed for its ability to rapidly identify asbestos phases by submitting the amphiboles anthophyllite, amosite, crocidolite and tremolite to spectroscopic analysis. All the phases were characterized by using XRD, SEM, TEM (CTEM, SAED), AEM and EDS techniques. This study demonstrates that accurate identification of the mineralogical phase can be attained by analysing the position in the Raman spectrum of the bands corresponding to the symmetric stretching modes (vs) and to the antisymmetric stretching modes (vas) of the different Si—O linkages. Raman spectroscopy thus proves to be an effective technique for rapidly distinguishing the different fibrous minerals examined.

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Both occupational and environmental exposure to asbestos-mineral fibres can be associated with lung diseases. The pathogenic effects are related to the dimension, biopersistence and chemical composition of the fibres. In addition to the major mineral elements, mineral fibres contain trace elements and their content may play a role in fibre toxicity. To shed light on the role of trace elements in asbestos carcinogenesis, knowledge on their concentration in asbestos-mineral fibres is mandatory. It is possible that trace elements play a synergetic factor in the pathogenesis of diseases caused by the inhalation of mineral fibres. In this paper, the concentration levels of trace elements from three chrysotile samples, four amphibole asbestos samples (UICC amosite, UICC anthophyllite, UICC crocidolite and tremolite) and fibrous erionite from Jersey, Nevada (USA) were determined using inductively coupled plasma mass spectrometry (ICP-MS). For all samples, the following trace elements were measured: Li, Be, Sc, V, Cr, Mn, Co, Ni, Cu, Zn, As, Rb, Sr, Y, Sb, Cs, Ba, La, Pb, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th, U. Their distribution in the various mineral species is thoroughly discussed. The obtained results indicate that the amount of trace metals such as Mn, Cr, Co, Ni, Cu and Zn is higher in anthophyllite and chrysotile samples, whereas the amount of rare earth elements (REE) is higher in erionite and tremolite samples. The results of this work can be useful to the pathologists and biochemists who use asbestos minerals and fibrous erionite in-vitro studies as positive cyto- and geno-toxic standard references.

For the first time, this paper reports a systematic and comparative study of the thermal behaviour of fibres of social, health, economic and industrial relevance using thermogravimetric and differential scanning calorimetry (TG/DSC). The mineral fibres selected for the study are: three chrysotiles samples, crocidolite, tremolite asbestos, amosite, anthophyllite asbestos and fibrous erionite.Powder X-ray diffraction (PXRD) and scanning electron microscopy combined with energy dispersive spectrometry (SEM/EDS) were used for the characterization of the mineral fibres before and after heating at 1000 or 1100 °C to identify the products of the thermal decomposition at a microscopic and structural scale and characterize their thermal behaviour.TG/DSC data allowed the determination of the structural water content and temperature stability.Furthermore thermal analysis provided a sensitive and reliable technique for the detection of small quantities of different mineral phases occurring as impurities. After thermal treatment, fibrous samples were completely transformed into various iron oxide, cristobalite and other silicate phases which preserved the original overall fibrous morphology (as pseudomorphosis). Only crocidolite at 1100 °C was partially melted and an amorphous surface was observed.

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The physicochemical properties of two commercial dispersions of iron nanoparticles were studied, together with their behavior in the room-temperature degradation in basic solutions of Acid Orange 7 (AO7), studied by UVÀvis spectroscopy. In one dispersion (bare-RNIP), water was the solvent, and in the other (M-RNIP) a biopolymer (sodium aspartate) was added (RNIP standing for reactive nanoscale iron particles and M for modified). The features of iron nanoparticles (size, morphology, presence of oxidized phases) were studied both in the dispersions as such and in the corresponding dried powders. A protecting role of the biopolymer was observed, as well as changes in the properties with time (aging). With bare-RNIP, the fraction of Fe 3 O 4 (magnetite) steadily increased with time at the expense of Fe 0 , eventually reaching 99%, and with M-RNIP, the Fe 0 content was higher at any time than with bare-RNIP: aging, however, brought about the formation of the Fe 3+ compound FeOOH besides magnetite. As for AO7 degradation, a similar behavior was observed with the two fresh dispersions: with M-RNIP, degradation was complete in a few minutes, and with fresh bare-RNIP, the same process was basically observed, though at a lower rate. In both cases, successive reactions were observed as a minor feature, for which an interpretation is advanced. Aging of M-RNIP does not prevent the degradation reaction: aging in the absence of the polymer, instead, leads, after 6 months, to an entirely different process, consisting in the mere adsorption through the phenol group of AO7 onto the magnetite external layer of bare-RNIP particles. Further aging of bare-RNIP prevents also this phenomenon. The different behavior of the two dispersions relates to the composition of iron nanoparticles. Reaction with water converts Fe 0 into magnetite. When Fe 0 is present and the thickness of the outer magnetite layer is moderate, AO7 degradation occurs. With a thick outer layer, only adsorption is possible, which does not take place on a fully oxidized surface.