Formation of Organo-Highly Charged Mica

Abstract

The interlayer space of the highly charged synthetic Na-Mica-4 can be modified by ion-exchange reactions involving the exchange of inorganic Na + cations by surfactant molecules, which results in the formation of an organophilic interlayer space. The swelling and structural properties of this highly charged mica upon intercalation with n-alkylammonium (RNH 3 ) + cations with varying alkyl chain lengths (R = C12, C14, C16, and C18) have been reported. The stability, fine structure, and evolution of gaseous species from alkylammonium Mica-4 are investigated in detail by conventional thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), in situ X-ray diffraction (XRD), and solid-state nuclear magnetic resonance (MAS NMR) techniques. The results clearly show the total adsorption of n-alkylammonium cations in the interlayer space which expands as needed to accommodate intercalated surfactants. The surfactant packing is quite ordered at room temperature, mainly involving a paraffin-type bilayer with an all-trans conformation, in agreement with the high density of the organic compounds in the interlayer space. At temperatures above 160 °C, the surfactant molecules undergo a transformation that leads to a liquid-like conformation, which results in a more disordered phase and expansion of the interlayer space.

Hydration properties of synthetic high-charge micas saturated with different cations: An experimental approach

“…These swelling high-charge micas, in which the layer charge can be adjusted, could be highly valuable for the decontamination of harmful divalent and heavy metal cations (Ravella et al, 2008) via ion-exchange reactions and for the selective removal of highly radioactive ions (Alba et al, 2006) and hydrocarbon molecules (Alba et al, 2011).…”

Synthesis and Characterization of New Macroporous SnO2Foams

“…The (001) diffraction peak for the as-prepared sample was observed at 3.3°, which corresponds to the basal spacing of 2.5 nm. Considering this repeating unit and the length of 1-hexadecylamine (~2.0 nm), 17 the hexadecylamine might be arranged into monolayer with a tilt angle between tin oxide particles. Successive thermal treatments were performed to examine the thermal stability of this sample.…”

New insights into surface-functionalized swelling high charged micas: Their adsorption performance for non-ionic organic pollutants

“…Table 2 shows the distribution coefficient, Kd, and the normalized coefficient to the organic content, Kom. The Kd decreases as the alkyl chain increases in parallel with the interlayer water content [19]. According to the values of the logarithms of the normalized sorption coefficients, it is found that the sorption efficiency of organomicas follows the order: C12-Mica-4 > C14-Mica-4 > C16-Mica-4 > C18-Mica-4, indicating that the sorption depends on the chain length of the organic cations.…”

“…Sheng et al [33], have found that aromatic compounds, due to their flat shape and presence of π-bond, interact strongly with the organic cation in the organoclay, causing a reorientation of the alkyl chains when alkylammonium cations lie parallel to the sheets of silicate and the alkylammonium adopted a vertical position. In Cm-Mica-4 the organization of the alkylammonium cations corresponds to inclined bilayers [19] and thus, phenol sorption do not affect to the arrangement of alkylammonium cations.…”

“…After adding hot deionized water, the mixture was stirred for 30 min at 50 °C and then the dispersion was centrifuged at 10,000 rpm for 20 minutes. The product was dissolved in a hot ethanol-water mixture (1:1) and stirred for 1 h at 50 ºC and then centrifuged [19,20]. The precipitate was dried at room temperature.…”