Influence of smectite suspension structure on sheet orientation in dry sediments: XRD and AFM applications

Abstract

The structure-building phenomena within clay aggregates are governed by forces acting between clay particles. Measurements of such forces are important to understand in order to manipulate the aggregate structure for applications such as dewatering of mineral processing tailings. A parallel particle orientation is required when conducting XRD investigation on the oriented samples and conduct force measurements acting between basal planes of clay mineral platelets using atomic force microscopy (AFM). To investigate how smectite clay platelets were oriented on silicon wafer substrate when dried from suspension range of methods like SEM, XRD and AFM were employed. From these investigations, we conclude that high clay concentrations and larger particle diameters (up to 5 microm) in suspension result in random orientation of platelets in the substrate. The best possible laminar orientation in the clay dry film, represented in the XRD 001/020 intensity ratio of 47 was obtained by drying thin layers from 0.02 wt.% clay suspensions of the natural pH. Conducted AFM investigations show that smectite studied in water based electrolytes show very long-range repulsive forces lower in strength than electrostatic forces from double-layer repulsion. It was suggested that these forces may have structural nature. Smectite surface layers rehydrate in water environment forms surface gel with spongy and cellular texture which cushion approaching AFM probe. This structural effect can be measured in distances larger than 1000 nm from substrate surface and when probe penetrate this gel layer, structural linkages are forming between substrate and clay covered probe. These linkages prevent subsequently smooth detachments of AFM probe on way back when retrieval. This effect of tearing new formed structure apart involves larger adhesion-like forces measured in retrieval. It is also suggested that these effect may be enhanced by the nano-clay particles interaction.

Microstructural and Swelling Properties of Ca and Na Montmorillonite: (In Situ) Observations with Cryo-TEM and SAXS

“…Recently, environmental scanning electron microscopy (E-SEM), atomic force microscopy (AFM), and transmission X-ray microscopy (TXM) have been used to study the clay–water systems, cf. refs − for example.…”

Why Treatment of the Water Based Clay Slurries are Not Effective; the Microstructural Review

“…All our results advocate [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], the structure building phenomenon within entire suspension may be blame for poor settling and dewatering. All these may be result of high water dielectric constant which polarising clay particles and generating electrostatic charge.…”

Effect of Modification with Methyl Methacrylate on the Mechanical Properties of Plectocomia kerrana Rattan

“…These results were reasonable because MMA polymerized throughout the rattan with good adhesion and improved the mechanical strength. According to previous reports, after MMA impregnation, the structures inside the vessel were of the category of smectite clay (Morris and Zbik 2009;Zbik and Frost 2010), and these types of particles had the ability to improve the mechanical properties of some materials, particularly wood-related materials (Islam et al 2012;Iman and Maji 2012). The bending and compressive strength of treated rattan were almost equal to that of C. manan rattan, the widely used industrial rattan species at present, which has bending and compressive strengths of 94.0 and 39.1 MPa, respectively.…”