Amphibole asbestos as micro to nanomaterials in the environment: their structure, compositions ii and properties

Transcription

1 Amphibole asbestos as micro to nanomaterials in the environment: their structure, compositions ii and properties Giancarlo Della Ventura University Roma Tre, Dipartimento di Scienze

2 Why so many asbestos/amphibole fibres in the environment? Anthropogenic/occupational occurrence

3 Asbestos in the ancient world It is believed that 4000 BC asbestos' long hair like fiberswere usedfor wicks in lamps andcandles candles. Between BC, embalmed bodies of Egyptian pharaohs were wrapped in asbestos clothsto to protectthebodiesfromdeterioration the deterioration. The ancient Romans used asbestos fibers to produce a cloth like material for table cloths andnapkins napkins. These cloths were cleaned by throwing them into a blistering fire.

4 During the medieval age, asbestos have been used for table clothings, cremation cloths, wicks etc. In 1280, Marco Polo wrote about clothing made by the Mongolians from a "fabric which would not burn." With the Industrial Revolution asbestos mining had a strong and steady growth, due to the myriad applications for its resistance to chemicals, water and electricity.

5 Asbestos mining and production increase around the world In the early 19th century, crocidolite (blue asbestos) had been found in South Africa, while in 1876, chrysotile (white asbestos) was discovered in Quebec. Australians began mining asbestos in New South Wales, in the 1880s. By the early 1900s, anthophyllite was mined in Finland and Amosite in Transvaal, South Africa; chrysotile from Swaziland and Zimbabwe was marketed around the world. By the early 1900s, asbestos production had grown worldwide to more than 30,000 tons annually.

6 Asbestos: from a miracle mineral to a killer

7 Natural occurrence: asbestos are very common constituents of igneous and metamorphic rocks Amphiboles: industrial (occupational) exposure very limited (95% chrysotile) Crocidolite, Amosite (Anthophyllite) Amphiboles: geological (non-occupational) occupational) exposure is extremely diffused Actinolite, Tremolite occur mostly as by-products of vermiculite, talc and chrysotile mining NOTE: crocidolite = riebeckite amosite (Asbestos Mines South Africa) = grunerite/cummingtonite

8 Asbestos amphiboles: geology The major world deposits of crocidolite and amosite occur within Precambrian banded ironstones (BIF) in southern Africa and western Australia. Individual levels are 0.5to 30 cm thick and groupin strata up to several tens of meters (reefs) over hundreds of kilometers.

9 Asbestos: geology In Australia, the asbestos deposits crop out within 1200 mts of iron formations belonging to the Hamersley group exposed for km 2

10 Asbestos: geology asbestos/

11 Asbestos: South Africa Asbestos developed within ironstones under low T/P metamorphic conditions. The crocidolite belt is 50 km wide and 400 km long.

12 The natural exposure to asbestos is mostly connected with ophiolites: the host rock for crysotile, tremolite and actinolite (besides other Mg-Fe silicates) From Vignaroli et al. (2011)

13 Notable examples in Italy: Alps, Calabria, Liguria Shear deformation structures From Vignaroli et al. (2014)

14 Notable examples: Appalachian Mts., Libby, El Dorado Hills, USA

15 fluoro edenite Biancavilla (CT)

16 Alb Hills, Alban Hill ROME

17 Serpentine Amphibole (93% of commercial use) (7% of commercial use) Chrysotile Actinolite, Tremolite, Anthophyllite, relatively simple and constrained Crocidolite, Amosite composition very complex systems 17

18 The different morfphological aspects of silicate amphiboles tremolite tremolite crocidolite (riebeckite) From Gunter et al (2007)

19 Which is the reson for such different morfphological aspects? NaNaCaMg 5 Si 8 O 22 (OH) 2 richterite Na cummingtonite it Na(NaMg)Mg 5 Si 8 O 22 OH 2 ferro richterite NaNaCaFe 5 Si 8 O 22 (OH) 2

20 The amphiboles fibers: an infernally complex chemical system

21 Amphiboles: double chain silicates I beam

22 The amphibole crystal structure: presently six known variants (space groups) a c The C2/m structure is by far the most common. All asbestos amphiboles are C2/m except anthophyllite (Pnma)

23 a B sites Na, Ca, Mg, Fe 2+, Mn, Li T sites Si, Al, Ti 4+, (Fe 3+ ) Ga, Ge A site Na, K, Pb, Ca, Anionic site OH, F, Cl, O 2 b c M sites Mg, Fe 2+, Fe 3+, Ti, Al, Mn, Cr, Zn, Li transition metals

24 2650 analitical points; only igneos amphiboles nz/minerals html#a

25 Chemical data for amphiboles from Biancavilla (Mazziotti et al., 2009) Chemical data for amphiboles from Libby (Meeker et al., 2003)

26 Amphiboles: analytical methods and calculation of the crystal-chemical formula A 0-1 B 2 C 5 Si 8 O 22 W 2 EDS or WDS Na, K,, (Ca), (Li) This site may have variable occupancy Ca, Na, Fe 2+, Mg, Li Mg, Al, Fe 2+, Fe 3+, Li OH, F, Cl, O 2

27 Amphiboles: analytical methods and calculation of the crystal-chemical formula A 0-1 B 2 C 5 Si 8 O 22 W 2 Need to quantify: 1) Light elements: H but also Li in peculiar cases. 2) Fe 3+ /Fe 2+ ratio, a very common problem for asbestos amphiboles 3) A site vacancy 4) Possible presence of O 2 at W sites, common in Ti/Fe 3+ amphiboles Calculations based on electroneutrality constraints difficult

28 Amphiboles: crystal-chemical formula based on EMPA data only 1) Anion content = 24 (Ox, OH, F, Cl) or 23 (Ox); the first choice is preferred, with (OH, F, Cl) = (2 2Ti) 2) Assumptions, number of cations set at: 13 CNK (excluding Mg, Fe at B sites) 15 cations (N)K, with Na all in B or all in A 16 cations, all sites full 3) The Fe 3+ /Fe 2+ ratio isadjusted d to electroneutrality li 4) This task is facilitated by several PC apps, es. AMPHIBOLE (A. Locock, 2013)( or AMPH2012 (Oberti et al. 2012) ( crystal.unipv.it/labcris/amph2012.zip)

29 Amphiboles: crystal-chemical formula 15 NK 13 CNK 15 K 1) Assuming 24(O,OH,F,Cl) and (OH,F,Cl) = 2 apfu with Fe either ferrous or ferric 2) All ferrous will provide the maximum cation sum; if the values for A, C, B, T exceed their normal values convert part of FeO into Fe 2 O 3 and adjust the site occupancies, following the different cation schemes 3) Adjust the Fe 3+ /Fe 2+ ratio electroneutrality Fixed points: T= 8 C = 5 B = 2 From Hawthorne et al. (2012)

30 Several nomenclature schemes have been adopted for amphiboles through the years (Leake et al., ), based on the A, B and T cation occupancy and stoichiometric ranges B (Mg, Fe, Mn, Li) 2 Mg Fe Mn Li amphiboles Na Ca Mg Fe Mn Li amphiboles This nomenclature did non account for Li and O 2- increasingly recognized in amphiboles, and to the link between local structure and charge arrangements, for example the role of O 2- on the distribution of high-charged cations Ca amphiboles Na Ca amphiboles Na amphiboles B Ca 2 B Na 2

31 W site B site Amphiboles: the new IMA nomenclature (Hawthorne et al. 2012) 1) Distinct arrangements of formalcharges at structural sites warrant ROOT NAMES; for any root name, different homovalent cation or anion is specified by a prefix. 2) Ineach subgroup, the A and C cations are used to assign specific names

32 From Oberti et al. (2012)

33 From Oberti et al. (2012)

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36 Example: the (ex) sodic-calcic calcic amphiboles now before

37 Synthetic amphiboles Amphibole synthesis is an extremely interesting technique for petrological, crystal chemical chemical and for biological/toxicological studies High Pressure internally Meltingfurnaces Externally heated heated vessels not for hydroxy amphiboles vessels

38 Starting materials: gels, oxide mixtures mgs Cold seal hydrothermal vessel Redox buffers few mm) Nobel metal tube: Au, Pt, AgPd

39 From Chernosky et al. (1998) From Greenwood (1963) Stability studies From Ernst (1966)

40 Crystal chemical studies: tetrahedral sites Si Ti in richterite (Della Ventura et al. 1991, 1993) A(NaCa)Mg 5 Si 8 O 22 (OH) 2 with A = Na, K, Rb A(NaCa)Mg 5 (Si 7 Ti)O 22 (OH) 2 for A = K or Na max sol. = 0.8 apfu Ti at 900 C, 1 kbar for A = Rb > 1.0 apfu at the same P,T conditions Ge in richterite (Senda et al., 2005) Ga in Ca amphiboles (Jenkins et al., 2000)

41 The structural data (Oberti et al., 1992) show that in richterite where C = Mg, the octahedral strip is large with respect the tetrahedral chain small large Si Ti favoured OH Fin Ti rich unfavoured

42 We try to fit parts, just like in a LEGO game

43 Synthesis of Fe Mg richterite (Della Ventura et al., 2016) NaNaCaMg 5 Si 8 O 22 (OH) 2 richterite NaNaCaFe 5 Si 8 O 22 (OH) 2 richterite

44 Ni and Co in richterite A(NaCa)Mg 5 Si 8 O 22 (OH) 2 A(NaCa)Ni 5 Si 8 O 22 (OH) 2 ( ) ( ) 2 A(NaCa)Co 5 Si 8 O 22 (OH) 2 with A = Na, K Crystal chemical studies: octahedral sites

45 Crystal chemical studies: Uncommon B site amphiboles Sr in richterite and potassium richterite A(NaCa)Mg 5 Si 8 O 22 (OH) 2 A = Na or K A(NaSr)Mg 5 Si 8 O 22 (OH) 2 Sr in tremolite (Gottschalk et al., 1998) Ca 2 Mg 5 Si 8 O 22 (OH) 2 Sr 2 Mg 5 Si 8 O 22 (OH) 2 B K in potassium richterite at 15 GPa (Yang et al., 1999) K(NaCa)Mg 5 Si 8 O 22 (OH) 2 K(KCa)Mg 5 Si 8 O 22 (OH) 2

46 Crystal chemical studies: Uncommon B site amphiboles B Mg in richterite: the first example of a P2 1 /m amphibole with a full A-site (Iezzi et al., 2004) Na(NaCa)Mg 5 Si 8 O 22 (OH) 2 C2/m Na(NaMg)Mg 5 Si 8 O 22 (OH) 2 P2 1 /m amphiboles in the Na 2 O-LiO 2 -MgO-SiO 2 - H 2 O (NLMSH) system Na(NaMg)Mg 5 Si 8 O 22 (OH) 2 P2 1 /m Na(LiMg)Mg 5 Si 8 O 22 (OH) 2 P2 1 /m

47 Tl richterite? Possible oxidation states: +3 and +1 Ionic radius: [12] Tl +1 = 1.7 Å [6] Tl +3 = 0.88 Å Nominal composition: Tl(NaCa)Mg 5 Si 8 O 22 (OH) 2 Na Tl

48 Textures offibres fibres depositionsused for toxicological experiments Toxicological experiments using different fibres concentrations of crocidolite MNHN from Buchanawald (South Africa) interacted in vitro with type II epithelial lung cells A549. Cell viability studied by using MTT test, trypan blue e cytometry

49 Cell viability as a function of increasing fibres concentrations 120 cytometry trypan blue MTT fibre weight per volume (mg/l) cell viability (% of the control) (%)

50 Image analysis mg/l mg/l agglomerated fibres single fibres mg/l % 25% 10 mg/l counts (% %) mg/l 50 mg/l % 83% 21% 17% 25 mg/l 50 mg/l mg/l % 32% 75 mg/l mg/l % 31% 100 mg/l aspect ratio

51 If you want to read more on amphiboles.

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53 X ray single crystal diffraction (SREF) as an analytical tool: refined site scatteringsand bond lengths Li bearing i