Evaluation of thermally treated asbestos by transmission electron microscopy

Yamamoto T.; Kida A.; Noma Y.; Terazono A.; Sakai S. (2014) Proceedings of 3RINCs and SWAPI 2014, pp. 2P-28

   Appropriate treatment of asbestos containing wastes is an important problem. In Japan, inertization of asbestos containing wastes by new techniques approved by the Ministry of the Environment is now promoted. A quantitative and sensitive testing method for asbestos in the treated materials is required in the approval process, but many of testing methods are only qualitative. Thus, we have developed a testing method for asbestos in the treated materials, which is consisted extraction of fibers from the treated materials and determination of fiber number concentration by transmission electron microscopy (TEM). We applied this testing method to the evaluation of thermally treated asbestos. Five kinds of asbestos standard samples were heated at 400 - 1500 °C for 2 hours. An aliquot of treated sample was dispersed in fiber-free water and filtered. TEM specimen was prepared from the filter and observed by TEM. It was found that asbestos fiber number concentrations of thermally treated asbestos decreased with raising treatment temperature, and became below 1×108 f/g (100 Mf/g) at more than 1000 °C for chrysotile and crocidolite, and more than 1400 °C for amosite and other amphibole asbestos.


Asbestos; Thermal treatment; Transmission electron microscopy