Quantitative XRD analysis of the dehydration–hydration performance of (Na⁺, Cs⁺) exchanged smectite

Abstract

A B S T R A C TThe clay mineral membrane is increasingly used, as a natural geological barrier, in wastewater treatment. The variation of the environmental condition (T, P, RH, etc.) induces probably several change on the materials structure. This work aims at characterizing the link between dehydration-hydration behavior, charge location, and the ionic radius, in the case of dioctahedral smectites, exchanged with Na + and Cs + cation, which are occurred from industrial waste. A natural montmorillonite and beidellite, with different charge location (respectively, dioctahedral and trioctahedral), are selected. The exchange process is directed using Na + and Cs + cations. The hydration hysteresis is investigated "in situ" as a function of relative humidity condition rates. All samples are studied using quantitative X-ray diffraction (XRD) analysis. This method allows us to determine the structural parameters obtained from the theoretical mixed layer structure used to fit experimental XRD patterns. For both Na + and/or Cs + exchangeable cations, an increase in hydration heterogeneity degree for the tetrahedral substituted smectite layer is noted and the position of exchangeable Cs + cation induce a homogeneous hydration trend which is interpreted by a new interlamellar space organization.

Interlamellar Space Configuration under Variable Environmental Conditions in the Case of Ni‐Exchanged Montmorillonite: Quantitative XRD Analysis

“…Such a complex mineralogy can, however, be partially revealed and quantified by comparing experimental X-ray diffraction (XRD) patterns with profiles calculated by assuming discrete clay phases or mixed-layer structure (MLS). Based on the examination of 00ℓ basal reflections, a lot of studies have been done on the hydration properties of this clay in order to understand the interlamellar space organization as function of relative humidity (RH) condition [9][10][11][12][13][14][15][16]. On the other hand, the interlayer water organization in presence of exchangeable heavy metal cations (i.e., Ni 2+ ) initiates the necessity to monitor the behavior of this barrier according to several climate changes and environmental factors that may affect the clay matrix in order to predict its short-and long-term performance.…”

Quantitative XRD Analysis of the Structural Changes of Ba-Exchanged Montmorillonite: Effect of an in Situ Hydrous Perturbation

“…The relationships between these probabilities and the abundances W i of the different types of layers are given by Oueslati [36,37]. All XRD profiles are simulated following the fitting strategy detailed by Oueslati [38][39][40].…”

Selective Microwave‐Assisted Pyrolysis of Cellulose towards Levoglucosenone with Clay Catalysts

“…Furthermore, thermally resolved small‐angle X‐ray scattering (SAXS) (Figure a, b, insets) shows the difference in water behaviour between the pillared and native bentonite. The step‐wise changes (w 2 , w 1 , w 0 ) of the basal spacing for the bentonite are related to a serial removal of discrete water sheets in the interlamellar space of this catalyst . The absence of such phenomenon for an Al‐PILC (Figure b, inset) indicates that Al 13 ‐complexes are acting as supportive pillars between the clay sheets, preventing their collapse.…”