Adsorption of Carbon Dioxide at −79° C. on High-Silica Sands

Abstract

THE presence of an adsorptive layer on the surface of the grains of high-silica sands, postulated as a result of determinations of the amount of methylene blue adsorbed from aqueous solution¹, has been confirmed by measurements of the adsorption of carbon dioxide at its vaporization temperature under atmospheric pressure. S-shaped isotherms were obtained, and the extent of the surface available to carbon dioxide molecules was calculated from the Brunauer–Emmett–Teller relationship². These values were compared with the superficial surface areas determined by an air permeability method³ or, for the finely powdered samples, by a light-extinction method⁴. The two sets of figures are given in Table 1 for three samples of silica and for four high-silica sands from the Lower Greensand exposure.