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Exfoliation and intercalation of montmorillonite by small peptides
https://orcid.org/0000-0003-1483-8405
Abstract Understanding structural changes in clay minerals induced by complexation with organic matter is relevant to soil science and agricultural applications. In this study, the effect of peptide storage in montmorillonite and the thermal stability of peptide–clay complexes were examined through characterization by X-ray diffraction (XRD), electron microscopy, UV absorption, and thermogravimetric analysis (TGA). XRD analysis of small peptide–montmorillonite clay complexes produced profiles consisting of reflections associated with the smectite 001 reflection and related peaks similar to that produced by a mixed layer clay mineral structure. Shifts in higher order diffraction maxima were attributed to disorder caused by the intercalation with the peptides. Increasing peptide concentrations resulted in greater shifts toward smaller 2θ from 6.37° (1.39nm) to 5.45° (1.62nm) as the interlayer space expanded. The expansion was accompanied by broadening of the 001 reflection (FWHM increases from 0.51 to 1.22° 2θ). The XRD line broadening was interpreted as caused by poorer crystallinity resulting from intercalation and tactoid exfoliation. SEM images revealed montmorillonite platelets with upwardly rolled edges that tend toward cylindrical structures with the production of tubules. High-resolution TEM images revealed bending of montmorillonite platelets, confirming exfoliation. The distribution of basal spacings in the micrographs was determined from the spatial frequencies obtained by Fourier analysis of density profiles. The distribution indicated the presence of discrete coherent crystallite domains. XRD and TGA results indicated that higher peptide concentrations resulted in a greater fraction of intercalated peptides and that surface adsorption of peptides mediated intercalation. Therefore, higher peptide concentration led to more stable organoclay complexes. However, UV absorption and TGA found that peptide adsorption onto montmorillonite had a finite limit at approximately 16% by weight.
Graphical abstract Display Omitted
Highlights Peptide intercalation of montmorillonite induces exfoliation in tactoids. The intercalation leads to poorer crystallinity in montmorillonite. The amount of total adsorbed peptides is dependent on concentration. Intercalation at higher peptide concentrations is mediated by surface adsorption.
Exfoliation and intercalation of montmorillonite by small peptides
https://orcid.org/0000-0003-1483-8405
Abstract Understanding structural changes in clay minerals induced by complexation with organic matter is relevant to soil science and agricultural applications. In this study, the effect of peptide storage in montmorillonite and the thermal stability of peptide–clay complexes were examined through characterization by X-ray diffraction (XRD), electron microscopy, UV absorption, and thermogravimetric analysis (TGA). XRD analysis of small peptide–montmorillonite clay complexes produced profiles consisting of reflections associated with the smectite 001 reflection and related peaks similar to that produced by a mixed layer clay mineral structure. Shifts in higher order diffraction maxima were attributed to disorder caused by the intercalation with the peptides. Increasing peptide concentrations resulted in greater shifts toward smaller 2θ from 6.37° (1.39nm) to 5.45° (1.62nm) as the interlayer space expanded. The expansion was accompanied by broadening of the 001 reflection (FWHM increases from 0.51 to 1.22° 2θ). The XRD line broadening was interpreted as caused by poorer crystallinity resulting from intercalation and tactoid exfoliation. SEM images revealed montmorillonite platelets with upwardly rolled edges that tend toward cylindrical structures with the production of tubules. High-resolution TEM images revealed bending of montmorillonite platelets, confirming exfoliation. The distribution of basal spacings in the micrographs was determined from the spatial frequencies obtained by Fourier analysis of density profiles. The distribution indicated the presence of discrete coherent crystallite domains. XRD and TGA results indicated that higher peptide concentrations resulted in a greater fraction of intercalated peptides and that surface adsorption of peptides mediated intercalation. Therefore, higher peptide concentration led to more stable organoclay complexes. However, UV absorption and TGA found that peptide adsorption onto montmorillonite had a finite limit at approximately 16% by weight.
Graphical abstract Display Omitted
Highlights Peptide intercalation of montmorillonite induces exfoliation in tactoids. The intercalation leads to poorer crystallinity in montmorillonite. The amount of total adsorbed peptides is dependent on concentration. Intercalation at higher peptide concentrations is mediated by surface adsorption.
Exfoliation and intercalation of montmorillonite by small peptides
https://orcid.org/0000-0003-1483-8405
Abstract Understanding structural changes in clay minerals induced by complexation with organic matter is relevant to soil science and agricultural applications. In this study, the effect of peptide storage in montmorillonite and the thermal stability of peptide–clay complexes were examined through characterization by X-ray diffraction (XRD), electron microscopy, UV absorption, and thermogravimetric analysis (TGA). XRD analysis of small peptide–montmorillonite clay complexes produced profiles consisting of reflections associated with the smectite 001 reflection and related peaks similar to that produced by a mixed layer clay mineral structure. Shifts in higher order diffraction maxima were attributed to disorder caused by the intercalation with the peptides. Increasing peptide concentrations resulted in greater shifts toward smaller 2θ from 6.37° (1.39nm) to 5.45° (1.62nm) as the interlayer space expanded. The expansion was accompanied by broadening of the 001 reflection (FWHM increases from 0.51 to 1.22° 2θ). The XRD line broadening was interpreted as caused by poorer crystallinity resulting from intercalation and tactoid exfoliation. SEM images revealed montmorillonite platelets with upwardly rolled edges that tend toward cylindrical structures with the production of tubules. High-resolution TEM images revealed bending of montmorillonite platelets, confirming exfoliation. The distribution of basal spacings in the micrographs was determined from the spatial frequencies obtained by Fourier analysis of density profiles. The distribution indicated the presence of discrete coherent crystallite domains. XRD and TGA results indicated that higher peptide concentrations resulted in a greater fraction of intercalated peptides and that surface adsorption of peptides mediated intercalation. Therefore, higher peptide concentration led to more stable organoclay complexes. However, UV absorption and TGA found that peptide adsorption onto montmorillonite had a finite limit at approximately 16% by weight.
Graphical abstract Display Omitted
Highlights Peptide intercalation of montmorillonite induces exfoliation in tactoids. The intercalation leads to poorer crystallinity in montmorillonite. The amount of total adsorbed peptides is dependent on concentration. Intercalation at higher peptide concentrations is mediated by surface adsorption.
Exfoliation and intercalation of montmorillonite by small peptides
Block, Karin A. (author) / Trusiak, Adrianna (author) / Katz, Al (author) / Alimova, Alexandra (author) / Wei, Hui (author) / Gottlieb, Paul (author) / Steiner, Jeffrey C. (author)
Applied Clay Science ; 107 ; 173-181
2015-01-22
9 pages
Article (Journal)
Electronic Resource
English
Exfoliation and intercalation of montmorillonite by small peptides
| Elsevier | 2015
Exfoliation and intercalation of montmorillonite by small peptides
| Online Contents | 2015
Enhanced exfoliation of montmorillonite prepared by hydrothermal method
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Enhanced exfoliation of montmorillonite prepared by hydrothermal method
| Online Contents | 2008
Enhanced exfoliation of montmorillonite prepared by hydrothermal method
| Online Contents | 2008