Methods for Determination of the Layer Charge of Smectites: A Critical Assessment of Existing Approaches

Abstract Layer charge is an important property of 2:1 phyllosilicates originating from isomorphic substitutions in the structure, vacancies octahedral sheet and unsatisfied bonds at edges crystals. It particular interest case smectites because it affects properties this mineral. Several methods have been proposed for determining layer smectites, namely structural formula method (SFM), alkylammonium (AAM), NH 4 -method, K-saturation method, O-D method. Most these used extensively past they all advantages shortcomings. The SFM AAM are based on different principles considered as primary methods. They a long time but consuming provide contrasting values, with yielding consistently lower values than SFM, especially low-charge smectites. remaining developed more recently calibrated over their counterparts. applied easily capable producing large amount data within short time. In sense can be both geological interpretations assessment bentonite deposits industrial scale.