The combination of oxalic acid with power ultrasound fully degrades chrysotile asbestos fibres

Our plain-English summary of The combination of oxalic acid with power ultrasound fully degrades chrysotile asbestos fibres, by F. Turci, M. Tomatis, S. Mantegna, et al (Journal of Environmental Monitoring, 2007).

The study

• Authors: F. Turci, M. Tomatis, S. Mantegna, G. Cravotto, B. Fubini
• Journal: Journal of Environmental Monitoring
• Published: 2007;9(10):1064-6
• Cited by: 13 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The simultaneous action of power ultrasound and oxalic acid, as a chelating agent, rapidly converts chrysotile asbestos into water soluble material and a non-asbestos debris, not classifiable as hazardous under worldwide safety regulations.

In plain English

This was a laboratory experiment testing a way to break down chrysotile asbestos. The authors suspended a commercial chrysotile sample from the former Balangero mine in Italy in 0.5 M oxalic acid and treated it with power ultrasound for 2.5, 13 or 21 hours. For comparison, some samples were given ultrasound in water alone. Without ultrasound, fibre shape did not change after 2.5 hours in oxalic acid. With both treatments combined, the long fibres broke into fibrils, and after 21 hours the original fibre shape was gone. Less than 40% of the starting material remained, and about 40% of the magnesium was released within the first 2.5 hours. Ultrasound alone left fragmented fibres that were still chrysotile. Raman analysis indicated that the remaining crystalline fibrils were antigorite, a non-asbestos serpentine mineral, rather than chrysotile. The authors concluded that the combined treatment fully degrades suspended chrysotile and suggested it could be used to clean asbestos-polluted water. They noted that the work was laboratory-scale. They also said it is not yet known whether the antigorite fibrils were in the original mineral or formed during treatment.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory experiment (short communication) on chemical and ultrasound treatment of asbestos fibres
• Who was studied: A commercial sample of chrysotile asbestos from the disused Balangero asbestos mine, Italy
• Exposure: Chrysotile fibres suspended in 0.5 M oxalic acid (pH about 1) and sonicated with power ultrasound (19.2 kHz, about 150 W) for 2.5, 13 or 21 hours. The 2.5 and 13 hour runs were also done without oxalic acid (ultrasound in water only) for comparison.
• Main results:
  • Without ultrasound, fibre shape did not change after incubation in pure water or in 0.5 M oxalic acid for 2.5 hours (results not shown).
  • With ultrasound plus oxalic acid, long chrysotile fibres were progressively converted into fibrils, and after 21 hours the original chrysotile shape was completely lost. A few very small fibrils were still seen.
  • After 21 hours of ultrasound plus oxalic acid, less than 40% of the starting material remained.
  • About 40% of the total magnesium was released after 2.5 hours of combined treatment. Magnesium release with ultrasound alone was very low.
  • Specific surface area increased much more with the combined treatment than with ultrasound alone, with most fragmentation occurring in the first few hours.
  • Ultrasound alone left fragmented fibres that were still chrysotile.
  • Micro-Raman spectroscopy indicated that the crystalline residue after 21 hours of combined treatment was antigorite, a non-regulated serpentine mineral, not chrysotile.
• The authors' conclusion: The authors concluded that power ultrasound combined with oxalic acid fully degrades suspended chrysotile, mostly to amorphous debris plus a smaller amount of very short antigorite fibrils, which they described as harmless. In their opinion, the technique could be used to decontaminate asbestos-polluted surface water or industrial waste water.
• Limitations the authors state:
  • The results are still laboratory-scale. Scale-up to industrial pilot equipment is in progress.
  • It is not yet known whether the antigorite fibrils were already present in the starting mineral or formed during treatment.

Mines named here

Asbestos mines this study is about. Each mine's page says who ran it, when it worked, and what it produced.

• Balangero mine, Balangero, about 20 km north of Turin, Piedmont

All asbestos mines

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile.

Medical terms in this study, explained in our Lexicon: Ultrasound, Chrysotile.

Related studies

• A new approach to the decontamination of asbestos-polluted waters by treatment with oxalic acid under power ultrasound — F. Turci, M. Tomatis, et al. (2008)
• Chrysotile asbestos detoxification with a combined treatment of oxalic acid and silicates producing amorphous silica and biomaterial — A. Valouma, A. Verganelaki, et al. (2016)
• The effects of naturally occurring acids on the surface properties of chrysotile asbestos — E.P. Holmes, L.M. Lavkulich (2014)
• Chrysotile asbestos is progressively converted into a non-fibrous amorphous material by the chelating action of lichen metabolites — S.E. Favero-Longo, F. Turci, et al. (2005)
• Microwave-assisted acid treatment for the mineral transformation of chrysotile as an alternative for asbestos waste management — S. Essih, L. Pardo, et al. (2024)
• In vitro reactivity of alveolar macrophages and red blood cells with asbestos fibres treated with oxalic acid, sulfur dioxide and benzo-3,4-pyrene — M.C. Jaurand, L. Magne, et al. (1981)

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