Differences between adsorption properties of two Rhodesian chrysotile samples. Relation with the DTA features introduced by leaching and grinding

Abstract

Substantial differences are founded between the absorption properties of two Rhodesian chrysotile samples (−1 and −2), which are, in most chemical and structural aspects, highly similar. The phenanthrene and CO2 amounts adsorbed are much less important on chrysotile-2 than on chrysotile-1. This indicates that chrysotile-2 has fewer basic surface sites. DTA and XRD results show that dry grinding and leaching produce a breakdown of the chrysotile structure, yield amorphous silica, and lower the temperature of the dehydroxylation peak. The dehydroxylation peaks of chrysotile-1 and -2 are really doublets. As the low-temperature component of the dehydroxylation peak is greater in chrysotile-2 than in chrysotile-1, the chrysotile-2 contains more ground and (or) leached fibers than chrysotile-1 and consequently shows weaker absorption properties. Keywords: chrysotile, leaching, phenanthrene adsorption.