Physicochemical studies in silicious dusts: Surface structure and related phenomena

Gibb, John G (1954) Physicochemical studies in silicious dusts: Surface structure and related phenomena. PhD thesis, University of Glasgow.

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Abstract

(1) Various important theories on the mechanism of the toxic reaction of inhaled silicious dusts are described In the Introduction. The Solubility Theory of silicosis, in particular, has stimulated research on the surface structure and properties of silicious dusts, and some recent results are discussed in the light of this concept. (2) An analytical method for the estimation of silica in solution is described, and the validity of the method is justified by comparison with results of recent investigations on the combination of silicate and molybdate ions. Changes in surface structure brought about by removal of the surface layer from crystalline quartz and fused-silica dusts by 40% hydrofluoric acid, and from Lochaline sand dust by a borate buffer (pH 7.5), are studied by electron- optical methods. The accompanying changes in electron- diffraction pattern show that the original surface layer is amorphous (estimated mean thickness 0.03 - 0.06mu); for quartz and Lochaline sand dusts there is some evidence of an inter-:mediate layer of very minute crystallites between the amorphous layer and the crystalline core. (3) The rate of solution of a pure rock crystal dust (e.g. Madagascar quartz) in a borate buffer (pH 7.5) is reduced by prior extraction with acid, whereas similar treatment of impure silicious dusts (e.g. Lochaline sand , a sandstone or orthoclase felspar) increases their solubility rates. The enhanced rate Is not due to regeneration of a disturbed amorphous layer of the type produced by crushing and grinding silica; and it can be reduced, sometimes back to its original value, by heat treatment within the temperature range ca. 60 - 1150

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: P D Ritchie
Keywords: Physical chemistry, Toxicology
Date of Award: 1954
Depositing User: Enlighten Team
Unique ID: glathesis:1954-72493
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 11 Jun 2019 11:06
Last Modified: 11 Jun 2019 11:06
URI: http://theses.gla.ac.uk/id/eprint/72493

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