Surface Area of Homoionic Illite and Montmorillonite Clay Minerals as Measured by the Sorption of Nitrogen and Carbon Dioxide

Abstract

The surface areas obtained by application of the B.E.T. theory to adsorption isotherms of nitrogen and carbon dioxide gases at 77~ and 195~ respectively on homoionic samples of illite and montmorillonite clays have been examined. The isotherms were obtained using a standard volumetric adsorption system and the results are compared with those obtained by Thomas and Bohor (1968) using a dynamic sorption system. Small amounts of residual water have been shown to have a marked influence on the accessibility of the internal surfaces of the montmorillonite clays to nitrogen and carbon dioxide adsorption, in this respect the standard outgassing procedure under high vacuum seems more efficient than that used in dynamic systems. The present data indicate that provided the sample has been satisfactorily outgassed there is little penetration of nitrogen or carbon dioxide gases into the quasi-crystalline regions of montmorillonite clays. With the exception of the caesium saturated montmorillonites the surfaces of the clays are more accessible to the smaller nitrogen molecules than to carbon dioxide assuming the values used for molecular area are correct.

High-pressure adsorption of methane on montmorillonite, kaolinite and illite

“…Considering that the mechanism of N 2 adsorption on Mt, such as the adsorption sites and influencing factors, has been well investigated ( Volzone and Ortiga, 2004), the N 2 adsorption data and parameters of clay minerals are herein referenced in the evaluation of the adsorption property of CH 4 . N 2 adsorption has typically been performed to obtain the surface area of clay minerals (Aylmore et al, 1970;Barrer and Reay, 1957;Kaufhold et al, 2010;Maes et al, 1997;Michot and Villieras, 2006). The obtained S BET values varied according to the measurement conditions and samples in previous reports.…”

“…The obtained S BET values varied according to the measurement conditions and samples in previous reports. This is because N 2 adsorption on clay minerals was affected by adsorbed water and the structure of the clay minerals (Aylmore et al, 1970;Michot and Villieras, 2006). For the former, the water was adsorbed on the hydrophilic surface of clay minerals and occupied the most adsorption sites and space, which left little space for N 2 molecules.…”

“…For example, clay minerals with a small interlayer distance, such as Na + -saturated montmorillonite, were used to represent the group of swelling clay minerals (Cheng and Huang, 2004;Ross and Bustin, 2009). However, the interlayer distance of Na + -saturated montmorillonite was approximately 0.1-0.3 nm (Aylmore et al, 1970;Hellerkallai, 2006;Michot and Villieras, 2006), which is smaller than the size of a CH 4 molecule (approximately 0.38 nm) (Suzuki et al, 1995;Volzone and Ortiga, 2004). Therefore, CH 4 adsorption on montmorillonite with a large interlayer distance (such as montmorillonite with calcium ions as the main interlayer cation species: Ca 2+ -montmorillonite, with an interlayer distance N 0.4 nm) was neglected.…”

X-ray Studies of Carbon Dioxide Intercalation in Na-Fluorohectorite Clay at Near-Ambient Conditions

“…In a previous work in the literature, at different experimental conditions and for another clay, Aylmore 23 criticized Thomas and Bohor´s conclusions 4 for using a relatively mild outgassing procedure. It was claimed that the residual water molecules in the system could explain the intercalation observed in their experiments.…”

Association of trace elements and dissolution rates of soil iron oxides

“…The specific surface area (SSA) was measured by the BET N 2 method (Aylmore et al 1970), with values of 129 and 32 m 2 g -1 for sample Kk and synthetic goethite, respectively. The flow-through reactor (46 mL in volume) used in this study has been described previously by Bibi et al (2011).…”