Simple, Rapid, and Low-Cost Detection and Recognition Method of Chrysotile Contained in Waste Building Materials at a Disaster by Dye Staining

Abstract

These days, disasters have frequently occurred in Japan and destroyed houses. A large amount of building materials containing asbestos has also been discarded after every disaster. We established a detection and recognition method of asbestos at simple, rapid and low cost by selective dyeing of asbestos in waste building materials. The building debris collected at disaster areas was crushed to a size of 1 to 2 mm and its dirty parts were removed by treating them with 20 % formic acid. A few particles of the washed sample were taken on a filter paper and dried on a hot plate for 5 minutes, and then stained with dyes. Asbestos in building materials is chrysotile over 95 % that is positively charged. On the other hand, main component in building materials is calcite and negatively charged. Therefore, chrysotile was stained with anionic dyes, such as erythrosine or eosin; the main component in building materials was stained cationic dyes, such as methylene blue, rhodamine B or cationic porphyrins. For example, chrysotile was stained in pink by erythrosine and the main component in building debris was stained in blue by methylene blue. Therefore, chrysotile in the building debris was easily detected by a stereomicroscope ( × 45 times). Furthermore, erythrosine did not stain crocidolite and amosite, and methylene blue stained crocidolite and amosite in blue and not chrysotile. That made it possible to detect chrysotile in waste building materials in distinction from crocidolite and amosite. Glass wool, ceramic wool and rock wool used in building materials were not stained with both methylene blue and erythrosine.