Smectite suspension structural behaviour

Morris, Gayle E.; Zbik, M.

doi:10.1016/j.minpro.2009.05.003

Cited by 49 publications

(25 citation statements)

References 15 publications

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“…1 can be drown that introduction of the Keggin macro-ion resulted in almost complete smectite intercalation when using Method 1 and partly intercalation when using Method 2 and Method 3. From microscopical observations [17], smectite consists of relatively large, flexible sheets with lateral dimension of $800-1000 nm and thickness of $1-10 nm. The platelet assembly of the sheets are stacked on top of each other, in a parallel fashion called a tactoid (stacks of parallel clay platelets at -10 Å A 0 separation).…”

Section: Resultsmentioning

confidence: 99%

Smectite flocculation structure modified by Al13 macro-molecules – As revealed by the transmission X-ray microscopy (TXM)

Zbik¹,

Martens²,

Frost³

et al. 2010

Journal of Colloid and Interface Science

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The aggregate structure which occurs in aqueous smectitic suspensions is responsible for poor water clarification, difficulties in sludge dewatering and the unusual rheological behaviour of smectite rich soils. These macroscopic properties are dictated by the 3D structural arrangement of smectite finest fraction within flocculated aggregates. Here, we report results from a relatively new technique, transmission X-ray microscopy (TXM), which makes it possible to investigate the internal structure and 3D tomographic reconstruction of the smectite clay aggregates modified by Al(13) Keggin macro-molecule [Al(13)(O)(4)(OH)(24)(H(2)O)(12)](7+). Three different treatment methods were shown resulted in three different micro-structural environments of the resulting flocculation. In case of smectite sample prepared in Methods 1 and 3 particles fall into the primary minimum where Van der Waals forces act between FF oriented smectite flakes and aggregates become approach irreversible flocculation. In case of sample prepared using Method 2, particles contacting by edges (EE) and edge to face (EF) orientation fell into secondary minimum and weak flocculation resulted in severe gelation and formation of the micelle-like texture in fringe superstructure, which was first time observed in smectite based gel.

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Section: Resultsmentioning

confidence: 99%

Smectite flocculation structure modified by Al13 macro-molecules – As revealed by the transmission X-ray microscopy (TXM)

Zbik¹,

Martens²,

Frost³

et al. 2010

Journal of Colloid and Interface Science

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“…The montmorillonite zeta potential for this montmorillonite as a function of pH as shown in [17] does not display an isoelectric point (iep). For all pH values investigated, the zeta potential of montmorillonite is negative and remains unchanged in magnitude with pH.…”

Section: Resultsmentioning

confidence: 93%

“…This flocked cellular structure may fill the entire vessel or be fragmented to individual flocks, which differ in size. When structured clay spans all volume that it is placed in, the suspension is gelled; there is no free settling in this system and further compacting may evolve slowly by structural re-arrangement of the entire network [17]. The slightest water movement influences shear, which promotes orientation in the entire network, as weak electrostatic forces cannot resist.…”

Section: Resultsmentioning

confidence: 99%

Transmission X-ray Microscopy—A New Tool in Clay Mineral Floccules Characterization

et al. 2012

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Abstract:Effective flocculation and dewatering of mineral processing streams containing clays are microstructure dependent in clay-water systems. Initial clay flocculation is crucial in the design and for the development of a new methodology of gas exploitation. Microstructural engineering of clay aggregates using covalent cations and Keggin macromolecules have been monitored using the new state of the art Transmission X-ray Microscope (TXM) with 60 nm tomography resolution installed in a Taiwanese synchrotron. The 3-D reconstructions from TXM images show complex aggregation structures in montmorillonite aqueous suspensions after treatment with Na + , Ca 2+ and Al 13 Keggin macromolecules. Na-montmorillonite displays elongated, parallel, well-orientated and closed-void cellular networks, 0.5-3 µm in diameter. After treatment by covalent cations, the coagulated structure displays much smaller, randomly orientated and openly connected cells, 300-600 nm in diameter. The average distances measured between montmorillonite sheets was around 450 nm, which is less than half of the cell dimension measured in Na-montmorillonite. The most dramatic structural changes were observed after treatment by Al 13 Keggin; aggregates then became arranged in compacted domains of a 300 nm average diameter composed of thick face-to-face oriented sheets, which forms porous aggregates with larger intra-aggregate open and connected voids.

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“…According to Morris and ¯bik (2009), the presence of smectite in fractions larger than 2 µm indicates an aggregate form of smectite. Kaolinite is dominant in the central zone of the gulf with an average of 40% in the fine fraction, whereas smectite has a high average (30 %) in the fine silt fraction in the coastal zone (Table 2).…”

Section: Outlet Of Mejerda Rivermentioning

confidence: 99%

Trace elements in different marine sediment fractions of the Gulf of Tunis (Central Mediterranean Sea)

Zaaboub

Oueslati²,

Helali³

et al. 2014

Chemical Speciation & Bioavailability

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Over several decades, the mouth of the Mejerda River (northern Tunisia) has received large amounts of mining tailings mainly containing Pb, Zn and Ba. We have measured the concentrations of major and trace elements (Al, Ti, P, K, Mg, Na, Ca, S, Fe, Cl, V, Cr, Co, Ni, Cu, Zn, Ga, Br, Rb, Sr, Y, Zr, Nb, I, Ba and Pb) in three different fractions of 45 surficial sediments using wavelength dispersive X-ray fluorescence. The size distribution of fine particles (<2 µm, 2-20 µm, 20-63 µm) revealed that clay and silt compounds were predominant (75-95%) in the deeper estuarine region. These condensed clay phases were mainly dioctahedral smectite, illite and kaolinite. The total organic carbon (TOC) concentration varies from 0.08 to 1.37 %. The C:N ratio varies from 1 to 17 indicating that the organic matter has a mixed marine and continental origin principal component analysis was used to determine the associations of trace elements with organic and/or inorganic phases of the sediment fractions. The correlations of Fe 2 O 3 , MnO 2 and P 2 O 5 with trace elements showed that amorphous Fe and Mn were the most active scavengers of dissolved metals from the Mejerda River. Cluster analysis clearly distinguished local trace element accumulations according to grain size fractions (< 2 µm and 2-20 µm) near the Ghar el Melh Lagoon and the Mejerda River.

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Smectite suspension structural behaviour

Cited by 49 publications

References 15 publications

Smectite flocculation structure modified by Al13 macro-molecules – As revealed by the transmission X-ray microscopy (TXM)

Smectite flocculation structure modified by Al13 macro-molecules – As revealed by the transmission X-ray microscopy (TXM)

Transmission X-ray Microscopy—A New Tool in Clay Mineral Floccules Characterization

Trace elements in different marine sediment fractions of the Gulf of Tunis (Central Mediterranean Sea)

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