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Volume 15, No. 6, November 2015, Pages 2332-2345 PDF(1.21 MB)  
doi: 10.4209/aaqr.2015.02.0108   

Optimal Treatment Condition for Changing Characteristics of Naturally Occurring Asbestos

Jieun Lee1, Chungsik Yoon1,2, Seunghon Ham1,2, Perng-Jy Tsai3

1 Department of Environmental Health, School of Public Health, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul 151-742, Korea2 Institute of Health and Environment, School of Public Health, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul 151-742, Korea3 Department of Environmental and Occupational Health, Medical College, National Cheng Kung University, 138, Sheng-Li Rd., Tainan 70428, Taiwan


  • The detoxification of naturally occurring asbestos (NOA) was challenged.
  • Combination of heat and acid treatment can change the characteristics of NOA.
  • Detoxification of NOA can reduce the health risk and provide safe disposal method.



Naturally occurring asbestos (NOA) refers to asbestos found as a natural component of rocks and soils. The purpose of this study was to determine effective methods for changing the characteristics of NOA. Unprocessed chrysotile-containing soils and rocks were treated using heat (700–1100°C for 1–3 hours) and combination (100–250°C, 0.3–1.0 M oxalic acid for 1–3 hours) methods. A polarized light microscope (PLM) and field emission scanning electron microscope (FE-SEM) with an energy-dispersion spectrometer (EDS) were used for the analysis of both untreated and treated samples. While PLM analyses revealed gradual change in optical properties in both heat and combination treatments, SEM/EDS analyses revealed morphological and chemical changes under conditions of combination treatment. The elemental composition of combination treated samples showed low levels of magnesium and high levels of silicon compared to untreated samples. The optimal treatment condition was 1 M oxalic acid at 250°C temperature for 1 hour. Combination treatment resulted in changes in NOA characteristics at lower temperatures than did heat treatment alone.



Keywords: Asbestos; NOA; Combination treatment; Oxalic acid; PLM.



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