Alkyl ammonium intercalation of Mozambican bentonite

Abstract

Organo-bentonites containing quaternary ammonium surfactants were prepared using purified bentonite from the Boane deposit in Mozambique. The intercalation was effected by intimate mixing of the surfactants into a concentrated dispersion of soda ash activated bentonite. TG indicated organic contents that exceeded CEC expectations by up to 21 mass %. XRD results were consistent with: (i) paraffin-type extended chain intercalation at tilt angles of 27 º to 33 º; and (ii) interdigitated monolayer intercalation of the C14 single alkyl chain surfactant and bilayer intercalation of the C16 double alkyl chains and its 1:1 mixture with the single chain surfactant. However, FTIR analysis revealed disordered alkyl chain conformations. White oil dispersions containing 10 mass % organo-bentonite (inorganic basis) featured high viscosities. They showed strong shear thinning behaviour confirming the ability of the montmorillonite particles to exfoliate.

Structural characterization of hexadecyltrimethylammonium-smectite composites and their potentiometric electrode applications

“…Moreover, the total amounts of waters removed from organosmectites below 200 • C are less than that of NaS and the elimination of the adsorbed waters from organosmectites occur at lower temperatures. This situation can be explained with the reduction of the surface energy and conversion of the silicate surface from hydrophilicity to hydrophobicity, which is in agreement with the results of the previously reported FTIR-ATR studies [24,26,36,41]. The thermal decomposition of organosmectites occurs in three stages: the dehydration of adsorbed water up to 140 • C, and then the decomposition of surfactant molecules which is followed by the dehydroxylation of smectite hydroxyl groups together with decomposition of organic carbonaceous residue of the surfactants, from 50 to 720 • C. The differentiation of the mass losses originating from dehydroxylation of smectite and decomposition of the organic cations by using the TG curves is highly difficult [80].…”

Surfactant-free dimer fatty acid polyamide/montmorillonite bio-nanocomposites

“…35.7 wt.% crystobalite as a major impurity [22]. The ammonium-modified bentonite showed a significant reduction in the sodium (2.11%) and calcium (0.39%) levels (described in terms of Na 2 O and CaO respectively).…”

Effects of organic modification of montmorillonite on the performance of starch-based nanocomposite films

“…The peaks at 2924 and 2850 cm −1 are attributed to the asymmetric and symmetric stretching vibrations of the methylene groups (\CH 2 − ) of aliphatic chains (Shah et al, 2013). The peak positions of the methylene asymmetric bands reflect the interlayer structure of OMts and the packing density of the chain methylenes (Massinga et al, 2010). The peaks near 2924 cm − 1 were shifted from 2929 cm −1 for 1231Mt to 2919.3 cm −1 for D1821Mt.…”