Magnesium oxide production from chrysotile asbestos detoxification with oxalic acid treatment

Our plain-English summary of Magnesium oxide production from chrysotile asbestos detoxification with oxalic acid treatment, by A. Valouma, A. Verganelaki, I. Tetoros, et al (Journal of Hazardous Materials, 2017).

The study

• Authors: A. Valouma, A. Verganelaki, I. Tetoros, P. Maravelaki-Kalaitzaki, E. Gidarakos
• Journal: Journal of Hazardous Materials
• Published: 2017;336:93-100
• Cited by: 11 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

This article describes the detoxification of pure chrysotile (Chr) asbestos by following an acid leaching treatment with oxalic acid dihydrate (Oxac) (H2C2O4·2H2O). Oxac was chosen due to its low environmental impact (or toxicity) and cost. We demonstrate the effectiveness of different concentrations of Oxac as proposed formulations. The results from FTIR, XRD and optical microscopy analyses indicated that all the applied treatments destructed the Chr structure while a new biomaterial, Glushinskite (Gls) was formed by the reaction between Oxac with the outer Brucite (Brc) (MgO2) layer surface of Chr. Oxac 0.05M was selected as the optimal concentration for an eight-day treatment for the detoxification. The heating of the supernatant of the above-treated solution at 480°C, yielded MgO in a considerable concentration (8.29% w/w). According to the energy consumption study the whole applied procedure is viable with an economic profit up to 4.3% and a low cost method of detoxification on the operation of a potential asbestos waste management site.

Copyright © 2017. Published by Elsevier B.V.

In plain English

In this laboratory experiment, researchers in Crete, Greece, treated pure chrysotile asbestos from the Asbestos Mines of Northern Greece with 0.05, 0.1 and 0.2 M oxalic acid at 26 °C, plus a distilled-water comparison. They examined it by X-ray diffraction, infrared spectroscopy and microscopy. After 10 days, chrysotile's typical signals were greatly reduced and magnesium oxalate (glushinskite) had formed. Phase contrast microscopy showed abundant fibers in untreated chrysotile but remarkably fewer in the treated sample. Under the stereoscope, treated samples still showed detectable fibrous structure, to a lesser extent. The authors chose 0.05 M as optimal, and eight days as best for producing magnesium oxalate. Heating solid material from the supernatant (liquid above the treated chrysotile) at 480 °C produced magnesium oxide; MgO made up 8.29% of this supernatant sample. Using the laboratory equipment's electricity use, the authors calculated a cost of 15.97 € for 60 g of magnesium oxide, against an estimated 16.65 € purchase price for 60 g of 99%-pure laboratory-reagent MgO. They concluded the method could be profitable up to 4.3%. Their detoxification description rested on these mineral and microscopy analyses.

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 on chemical treatment of chrysotile asbestos, with a cost estimate
• Who was studied: pure chrysotile asbestos supplied by the Asbestos Mines of Northern Greece; no people were studied
• Exposure: chrysotile treated with oxalic acid dihydrate at 0.05, 0.1 and 0.2 M at 26 °C (Table 1), compared with chrysotile in distilled water; the solid phase of the supernatant was later heated at 480 °C
• Main results:
  • In X-ray diffraction of chrysotile treated with 0.1 M and 0.05 M oxalic acid, the two peaks characteristic of chrysotile almost disappeared after 10 days, and new peaks corresponding to magnesium oxalate appeared
  • A new peak corresponding to forsterite was also identified in the treated samples
  • In infrared spectroscopy, the main chrysotile peaks were remarkably decreased after 10 days of oxalic acid treatment
  • Under phase contrast microscopy, fibers were abundant in the untreated sample and remarkably reduced in the sample treated with the optimum (0.05 M) concentration
  • Under the stereoscope, the fibrous structure of chrysotile remained detectable in the treated samples, to a lesser extent than in the untreated reference
  • The largest quantity of magnesium oxalate in the supernatant was found after 8 days of treatment, so an eight-day treatment was chosen
  • The solid phase of the supernatant was thermally treated at 480 °C to produce magnesium oxide
  • SiO2 content was higher in the treated sample (52.05%) than in untreated chrysotile (41.39%)
  • In the elemental analysis, MgO made up 8.29% of the supernatant sample (S8); this is the share of MgO in that sample, not the purity of recovered MgO
  • Treating 289.5 cm3 of chrysotile to obtain 60 g of MgO was calculated, from the electricity use of the laboratory equipment, to cost 15.97 €
  • The comparison price was the estimated purchase price of laboratory-reagent MgO (99% purity), 16.65 € per 60 g
• The authors' conclusion: The authors concluded that 0.05 M oxalic acid was optimal and that the method destroyed the chrysotile structure and produced magnesium oxalate. They also concluded that heating the supernatant at 480 °C yielded MgO, and that, according to their energy consumption study, the procedure was viable with a profit up to 4.3%.

Topics

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

Related studies

• Chrysotile asbestos detoxification with a combined treatment of oxalic acid and silicates producing amorphous silica and biomaterial — A. Valouma, A. Verganelaki, et al. (2016)
• 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)
• The combination of oxalic acid with power ultrasound fully degrades chrysotile asbestos fibres — F. Turci, M. Tomatis, et al. (2007)
• 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)
• Microwave-assisted acid treatment for the mineral transformation of chrysotile as an alternative for asbestos waste management — S. Essih, L. Pardo, et al. (2024)
• Plants, Microorganisms and Their Metabolites in Supporting Asbestos Detoxification-A Biological Perspective in Asbestos Treatment — S. Łuniewski, W. Rogowska, et al. (2024)

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