Abstract:An understanding of the interaction mechanisms between exchangeable cations and layered silicates is of interest from both a basic and an applied point of view. Among 2:1 phyllosilicates, a new family of swelling high-charge synthetic micas has been shown to be potentially useful as decontaminant. However, the location of the interlayer cations, their acidity and the water structure in the interlayer space of these silicates are still unknown. The aim of this paper was therefore to study the hydration state of… Show more
“…X-ray diffractograms of the Na-M n (Figs 1a and S3a) show patterns that corresponded to that previously reported for swelling high-charged micas 54 with a unique 001 reflection corresponding to a basal space of 1.22 nm due to hydrated Na + 55 .Figure 1XRD in the 5–8° 2θ range of Mica-2 ( n = 2), left graph, and, Mica-4 ( n = 4), right graph. ( a ) NaM n , ( b ) Ch-NaM n -A, ( c ) Ch-NaM n -B, ( d ) Ch-NaM n -C, ( e ) Ch-NaM n -D, and, ( f ) Ch-NaM n -E.…”
Bionanocomposites based on layered inorganic components, as clays, and polymers of biological origin, as chitosan, have a major impact in medical and environmental fields, being economical and environmentally friendly materials. Na-M
n
micas (
n
= 2 and 4) with controlled surface charge, high cation exchange capacity and swelling behaviour, are attractive inorganic composite components that exhibit improved adsorption properties compared to other inorganic solids which makes them potentially useful for bionanocomposites. The goal of this research was to explore the potential use of those synthetic brittle micas to form eco-friendly bionanocomposites with chitosan biopolymer. Hence, chitosan-mica bionanocomposites were prepared by ion-exchange reaction between chitosan solution and synthetic high charge mica. X-ray diffraction, Fourier transform infrared spectroscopy, thermal analysis, MAS-NMR spectroscopy and zeta-potential have been employed for bionanocomposites characterization. The results showed that the adsorption of chitosan is effective, although a chitosan portion remains in the outer surface being hydrogen-bonded to the tetrahedral sheet of the silicate.
“…X-ray diffractograms of the Na-M n (Figs 1a and S3a) show patterns that corresponded to that previously reported for swelling high-charged micas 54 with a unique 001 reflection corresponding to a basal space of 1.22 nm due to hydrated Na + 55 .Figure 1XRD in the 5–8° 2θ range of Mica-2 ( n = 2), left graph, and, Mica-4 ( n = 4), right graph. ( a ) NaM n , ( b ) Ch-NaM n -A, ( c ) Ch-NaM n -B, ( d ) Ch-NaM n -C, ( e ) Ch-NaM n -D, and, ( f ) Ch-NaM n -E.…”
Bionanocomposites based on layered inorganic components, as clays, and polymers of biological origin, as chitosan, have a major impact in medical and environmental fields, being economical and environmentally friendly materials. Na-M
n
micas (
n
= 2 and 4) with controlled surface charge, high cation exchange capacity and swelling behaviour, are attractive inorganic composite components that exhibit improved adsorption properties compared to other inorganic solids which makes them potentially useful for bionanocomposites. The goal of this research was to explore the potential use of those synthetic brittle micas to form eco-friendly bionanocomposites with chitosan biopolymer. Hence, chitosan-mica bionanocomposites were prepared by ion-exchange reaction between chitosan solution and synthetic high charge mica. X-ray diffraction, Fourier transform infrared spectroscopy, thermal analysis, MAS-NMR spectroscopy and zeta-potential have been employed for bionanocomposites characterization. The results showed that the adsorption of chitosan is effective, although a chitosan portion remains in the outer surface being hydrogen-bonded to the tetrahedral sheet of the silicate.
“…2, stage 1, Table 1), indicating that their hydration states are constant with time. The values are 12 to 14 Å and correspond to the previously observed values in these materials (Pavón et al, 2013). Bihydrated layers (2W) with H2O on each side of the interlayer midplane produces a 001 reflection at d001=14.9-15.7 Å (Ferrage et al, 2005).…”
Section: Sample Characterization X-ray Diffraction Patterns At Variasupporting
confidence: 84%
“…Na-n-Mica were exchanged with solutions of Li + , K + , Mg 2+ , and Al 3+ salts at concentrations that ensured that the molar content of the cation was 10 times the cation-exchange capacity (CEC) of the mica (Pavón et al, 2013). The most important characteristics of these ions in solution are displayed in Table 1S (Supporting Information).…”
Section: Cation-exchange Processmentioning
confidence: 99%
“…7447-41-8, >99.0% purity). The ion-exchange process was described elsewhere (Pavón et al, 2013) and the purity of the samples analyzed by XRD (Pavón et al, 2014). This exchange method prevents the modification of the silicate framework and consequently, XRF analyses were not needed.…”
Swelling and dehydration under minor changes in temperature and water vapor pressure is an important property that clays and clay minerals exhibit. In particular, their interlayer space, the solid-water interface and the layers' collapse and re-expansion have received much attention because it affects to the dynamical properties of interlayer cations and thus the transfer and fate of water and pollutants. In this contribution, the dehydration and rehydration mechanism of a swelling
“…A similar shift has already been observed in the 29 Si 251 frequencies of high charge swelling silicates, and was attributed to the formation of inner sphere 252 complexes between the interlayer cations and the basal oxygen of the silicate tetrahedral layer. 66 …”
A family of tetradecylammonium micas is synthesized using synthetic swelling micas with high layer charge (Na n Si 8−n Al n Mg 6 F 4 O 20 •XH 2 O, where n = 2 and 3) exchanged with tetradecylammonium cations. The molecular arrangement of the surfactant is elucidated on the basis of XRD patterns and DTA.The ordering conformation of the surfactant molecules into the interlayer space of micas is investigated by IR/FT, 13 C, 27 Al, and 29 Si MAS NMR. The structural arrangement of the tetradecylammonium cation in the interlayer space of highcharge micas is more sensitive to the effect of the mica layer charge at high concentration. The surfactant arrangement is found to follow the bilayer-paraffin model for all values of layer charge and surfactant concentration. However, at initial concentration below the mica CEC, a lateral monolayer is also observed. The amount of ordered conformation all-trans is directly proportional to the layer charge and surfactant concentration.
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