The rapid estimation of the layer charges of 2:1 expanding clays from a single alkylammonium ion expansion

Abstract

: An empirical method to estimate rapidly both mean total layer charge and location of charge in smectites and vermiculites is presented, involving exchange with a longchain alkylammonium ion before and after the Greene-Kelly test. The method utilizes an empirically determined relationship between XRD basal spacings and the mean layer charges calculated from the conventional n-alkylammonium ion-exchange technique using simple linear regression models to describe the relationships for both monolayer-bilayer and bilayerpseudotrimolecular layer transitions. The method provides a rapid estimation of these charge parameters and facilitates the proper identification of both smectites and vermiculites consistent with the AIPEA criteria for classification based on total layer charge. It is considered superior to conventional methods of differentiation based mainly on expansion and collapse behaviour.

Change in Layer Charge of Smectites and Smectite Layers in Illite/Smectite During Diagenetic Alteration

“…Mean layer charges of the smectite samples were estimated using a single alkylchain of n c = 12 or n c = 18 according to the convenient alkylammonium ionexchange method presented by Olis et al (1990). The alkylamines of nc = 12 is commercially available as dodecyl-and n c = 18 is octadecylammonium chlorides and it is not necessary to prepare them from their respective amines.…”

“…The alkylammonium ion-exchange method (Olis et al 1990) applied to the samples with 100% smectite revealed that the smectite samples at shallow burial depths (< about 1000 m) have similar layer charges of approximately 0.56. The layer charge of smectites continuously increases from approximately 0.56 to 0.73 with increasing stratigraphic depth (Figure 4).…”

“…The layer charge characteristics of smectites have been examined by expansion behavior tests, which include ethylene glycol and glycerol solvation (Brindley 1966;Sato et al 1992), Greene-Kelly test (GreeneKelly 1953(GreeneKelly , 1955Malla and Douglas 1987a, 1987b, 1987c and alkylammonium method (Lagaly and Weiss 1969;Stul and Mortier 1974;Stanjek and Friedrich 1986;Hausler and Stanjek 1988;Olis et al 1990). These tests, for US samples, provide information for only expandable smectite layers in US.…”

Characterization of Untreated and Alkylammonium Ion Exchanged Illite/Smectite by High Resolution Transmission Electron Microscopy

“…Alkylammonium ion treatment has been shown to provide a stable expansion ofinterlayers under HRTEM conditions (Riihlicke and Niederbudde 1985, Bell 1986, Klimentidis and Mackinnon 1986, Vali and K6ster 1986, Marcks et al 1989, Ghabru et al 1989, even though it causes some disruption of the clay fabric (Lee and Peacor 1986). Furthermore, the type of structural arrangement adsorbed alkylammonium ions adopt can be inferred from the thickness of expanded interlayers on HRTEM images which, in turn, can be used to estimate the layer charge density of the expandable layers (Marcks et al 1989, Ghabru et al 1989, Olis et al 1990.…”

Layer Charge and Charge Distribution of Smectites: A Parameter Which Controls Important Physical Properties of Bentonites

“…Smectite total layer charge and the heterogeneity of this charge from layer to layer can been measured by a variety of methods, including: (1) micro-calorimetry (Talibudeen and Goulding 1983), in which the heat released during determination of an exchange isotherm is related to different types of exchange sites and hence to charge heterogeneity; (2) measurement of the structural formula using chemical or microbeam methods (Weaver and Pollard 1973, Newman and Brown 1987, Christidis 2006, in which the oxide content of a purified smectite sample is measured and then converted into a structural formula; (3) by XRD analysis after saturation with inorganic or organic cations (Tettenhorst and Johns 1966, Cicel and Machajdik 1981, Stul and Mortier 1974, Lagaly 1981, Olis et al 1990) and (4) by computer modeling of XRD traces of K-saturated ethylene glycol solvated smectites (Christidis and Eberl 2003). Microcalorimetry does not yield quantitative estimation of the layer charge.…”