The Micropore Size Distributions of Clay Mineral Systems

Abstract

SumnmyThe micropore (< IOO A) size distributions of compacted clay mineral systems have been examined by means of low-temperature Nt sorptionisotherms to saturation. The calculation of pore sizes was based on the application of the Kelvin equation, corrected for the adsorbed f i l m thickness, to the parallel plate model.Clay-mineral systems have been shown to exist with a high degree of parallel alignment of the plate-shaped crystals. This results in a high proportion of microporosity and in relatively discrete pore sizes.In montmorillonite clap much intercrystalline overlap area in the dry matrix is inaccessible to N, sorption. The structure of these systems may be governed partly by the effect, in suspension, of electrostatic interaction between the charged particles on crystal size, but largely by mechanical interaction on sedimentation and the size of the exchangeable catiom present.

Pre-activation of aerosol particles by ice preserved in pores

“…Therefore, the majority of the pores in illite NX particles are likely between 3 and 6 nm in diameter or even narrower. This is in agreement with results from gas sorption measurements showing that most of the porosity of illites arises from the void spaces between nearly parallelaligned plates of primary particles resulting in pores of 2-5 nm, (Marcolli, 2014;Aylmore, 1974: Aylmore andQuirk, 1967). The relevance of pore width for pre-activation is further supported by the results of the zeolite samples.…”

Pre-activation of ice-nucleating particles by the pore condensation and freezing mechanism

“…The maximum of the differential pore-size distribution for an illite sample, for example, was located at plate separations between 2 and 4 nm whereas pores larger than 5 nm were much less frequent (Aylmore and Quirk, 1967). Smaller ice-filled pores can contribute to the dominant depositional ice growth mode observed for illite NX particles at T < 237 K (Fig.…”

“…2.1.1). Also in the case of clay minerals like illite, the respective sites for pore condensation and freezing are void spaces arising from the interleaving of plates in the aggregate particle (Aylmore and Quirk, 1967). For soot particles, capillary condensation most likely occurs in the empty spaces between aggregate primary particles (Marcolli, 2014).…”

Reply to comments of Thomas, Bohor and Frost on Aylmore, L. A. G., Sills, I. D. and Quirk, J. P. (1970) The surface area of homoionic illite and montmorillonite clay minerals as measured by the sorption of nitrogen and carbon dioxide, Clays and Clay Minerals18, 91.

“…This variation is not disputed. However, the question of the correct values to use for the saturation vapour pressure and molecular area of carbon dioxide at 195~ will await further elucidation and should not be allowed to obscure the real point of contention debated in our paper which is whether or not these gases penetrate into the quasi-crystalline (Aylmore and Quirk, 1960;Quirk, 1967) regions of the montmorillonite matrix and their use for measurement of the external surface area of these regions. As indicated in the following notes, acceptance of the values assigned by Thomas and Bohor (1968) would not reverse our conclusions with respect to these points.…”

“…Pore size distributions (Aylmore and Quirk, 1967) show that for most of these materials the majority of the surface area external to the quasi-crystalline regions lies in pores of some 25.~-30~. plate separation.…”