The failure of using equilibrium adsorption of fosthiazate onto montmorillonite clay particles to predict their cotransport in porous media as revealed by batch and column studies

This research developed a novel poly(trifluoropropylmethylsiloxane) (PTMS)/montmorillonite nanoparticles, for technologic applications. PTMS /MMT nanoparticles were prepared by the miniemulsion polymerization method. Montmorillonite clay was encapsulated within a fluorinated cyclosiloxane (1,3,5-tris(trifluoropropylmethyl)cyclotrisiloxane) to give stable water based nanocomposite latex, using miniemulsion polymerization technique. The resulting composite latex was characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS) and RX diffraction. The particles stability was investigated by sedimentation and surface tension measurements. An efficient cationic/nonionic surfactant mixture was used in order to achieve the best compatibility with the monomer. TEM and RX data revealed the partial embedding of montmorillonite in the spherical polymer based nanoparticles. According to DLS measurements, the encapsulated clay particles conserve their size throughout the polymerization process. The melt processing of poly(trifluoropropylmethylsiloxane) matrix to encapsulate the montmorillonite clay was also carried out for comparison purposes.

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Electrokinetic study of the adsorption of ethyl violet and crystal violet by montmorillonite clay particles

Canadian Journal of Chemistry ◽

10.1139/v97-620 ◽

1997 ◽

Vol 75 (12) ◽

pp. 1868-1877 ◽

Cited By ~ 11

Author(s):

Laurier L. Schramm ◽

Shmuel Yariv ◽

Dipak K. Ghosh ◽

Loren G. Hepler

Keyword(s):

Crystal Violet ◽

Dye Adsorption ◽

Montmorillonite Clay ◽

Degree Of Saturation ◽

Adsorption Parameters ◽

Clay Particles ◽

Electrophoretic Mobilities ◽

Ethyl Violet ◽

Different Types ◽

Adsorption Phenomena

Electrophoretic mobilities of mixtures of a montmorillonite clay (in different exchangeable metal cation forms) and increasing amounts of two cationic dyes (ethyl violet and crystal violet) were measured. Electrophoretic mobilities were found to vary between −60 × 10−5 and +40 × 10−5 cm2 s−1 V−1. For both the dyes, the degree of saturation at which the isoelectric point (IEP) occurs, decreases with increasing valency of the metal cations. An effort was made to connect the IEP, maximum flocculation, and dye adsorption parameters. An important adsorption parameter is the transition saturation (TS), the saturation beyond which adsorption by organophilic attractions occurs in addition to adsorption by electrical and (or) π-interactions. It was found that maximum flocculation occurs before the IEP for all the exchangeable cations tested, but the IEP is reached at similar saturations to the TS for most of the cations. These results have been interpreted in terms of different types of adsorption phenomena and particle associations. Keywords: clay, adsorption, dye, ion exchange, electrokinetic charge.

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