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

Minerals

Walid Oueslati¹  Marwa Ammar¹  Nejmeddine Chorfi² 

[1] Departement de Physique, Faculté des Sciences de Bizerte, Université de Carthage, Zarzouna 7021, Tunisia; E-Mail:;Department of Mathematics, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia; E-Mail:

关键词: cation exchange;    dehydration;    clay minerals;    X-ray diffraction (XRD);   

DOI  :  10.3390/min5030507

来源: mdpi

【 摘 要 】

The structural changes along the c axis, of the Ba-exchanged montmorillonite (Swy-2-Ba), under variable relative humidity (% RH), is investigated. In this regard, the arrangement, amount and position of both exchangeable cation and the water molecules in the interlamellar space (IS), are evaluated. This aim is achieved using the X-ray diffraction (XRD) profile modeling approach that consists of comparing experimental and theoretical patterns calculated from structural models. The contributions of the hydration states and the interlayer water amounts, as a function of the % RH, are registered by quantitative XRD investigation. The validated structural models are heterogeneous, suggesting various proportions of layer types at different RH ranges, which means the coexistence of different mixed layer structure MLS packages, exhibiting different proportions of layers with contrasting hydration states. This result is attributed to the orientation of the applied hydration sequence. Indeed, the interlayer water molecule amounts, which led to the appearance of a logic hydration hysteresis, are strongly affected by hydrous perturbation.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.