Influence of Energy State of Montmorillonite Interlayer Cations on Organic Intercalation

Abstract

It is well known that the intercalation of montmorillonite (Mt) with organic cations is a fast process. During the intercalation, the interaction between the original cations and the structure layer of Mt keeps changing, and the basal spacing of Mt keeps increasing until an organic environment has been built in the interlayer. Many properties of Mt also change during the intercalation, such as hydrophobic or hydrophilic property and thermal stability. In this research, the impact of intercalation on the properties of Mt was studied by investigating the change in basal spacing and energy that coordinates the interlayer cations during the intercalation of Mt with organic cations. The interaction between interlayer cations and the layers in the Mt structure and the change in the system energy were obtained by using molecular dynamics simulation. All the experiment and calculation results provide a theoretical proof in organic intercalation mechanism.

Electrostatic coupling and water bridging in adsorption hierarchy of biomolecules at water–clay interfaces

“…1 C ); a similar phenomenon was also reported previously with adsorbed organic compounds on Ca-MMT ( 27 ). It is acknowledged that the extent of smectite layer expansion would depend on the type of charge-compensating metal cations ( 41 – 48 ), but, here, we attributed the d 001 decrease to the change in the conformation of the adsorbed biomolecules with Mg-MMT. For instance, compared to the p- coumarate configuration with Na-MMT ( Fig.…”

Synthesis and Impedance Spectroscopy of Poly(p-phenylenediamine)/Montmorillonite Composites

“…The basal spacing expresses the sum of the thickness of one aluminosilicate layer and interlayer spacing, which can be affected by the size and orientation of interlayer ions. Assuming the thickness of the aluminosilicate layer of 9.8 Ǻ [ 34 ], the interlayer spacing for PPDA-2 and PPDA-5 composites expanded from 0.7 Ǻ (for pure MMT) to 2.7 Ǻ. This is a consequence of the intercalation process of PPDA chains in between the clay layers.…”

Effect of Crystal Chemistry Properties on the Distribution Characteristics of H2O and Na+ in Na-Montmorillonite Interlayer Space: Molecular Dynamics Simulation Study

“…It can be seen from Figure 5b that the relative concentration curves of Na + are unimodal and change gradually to irregular distribution as the amount of tetrahedral substitution sites increases. This indicates that Na + are distributed along the central axis when isomorphic substitution mainly occurs in octahedral layers of Na-MT, but Na + tend to move towards tetrahedral sheets when the amount of tetrahedral substitution sites increases [4]. In Na-MT with the same layer charge, Na + are closer to the tetrahedral sheets than octahedral layers, when the amount of tetrahedral isomorphic substitution sites increases, the electrostatic interaction between Na + and Na-MT tetrahedral isomorphic substitution sites will be strengthened due to the short-range spatial effect.…”

“…The z-axis concentration profiles can reflect the density characteristic of particles in interlayer of Na-MT [4], therefore, the density variation tendency of H 2 O and Na + can be predicted and the influence mechanism can be explained by analyzing the simulation results. In this part, it was calculated on the basis of NVT simulation results and the protocols are set as follows: the number of bins was 100, the width of smoothed profile was 1.0 bin.…”

“…As a result of heterovalent isomorphic substitution, the layers of MT are permanently negatively charged. Therefore, some exchangeable cations such as Na + , Ca 2+ in the natural environment can enter the layers of MT to balance the negative charges between MT layers and form various types of MT [4,5].…”