Abstract:
The dataset shows electron microscopy imaging of hydrophobically modified chitosan (HMC) biopolymer connecting halloysite nanotubes (HNT) at the oil-water interface and optical micrographs of the emulsions. The dataset includes the image files presenting the nanotubular morphology and elemental composition of the HNT, nuclear magnetic resonance (NMR) spectra of native chitosan and HMC, optical microscopy images of dodecane-in-water emulsions, zeta potential of HMC solutions and dodecane-in-water emulsions, Cryogenic Scanning Electron Microscopy (Cryo-SEM) images of dodecane-in-water emulsions, photographs showing colloidal stability of HNT as a function of HMC concentration, SEM of native HNT and HNT with adsorbed HMC, and Fourier transform infrared (FTIR) spectra of native HNT and Span 80 loaded HNT as well as dynamic interfacial tension measurements for dodecane–water interface laden with HMC, HMC/HNT, and HMC/Span 80 loaded HNT.
Suggested Citation:
John, Vijay T.. 2019. Electron microscopy imaging of hydrophobically modified chitosan biopolymer connecting halloysite nanotubes at the oil-water interface for synthetic emulsion stabilization. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7DZ06WX
Purpose:
Our objective here is to design a mixed emulsifier system based naturally occurring halloysite nanotubes and hydrophobically modified chitosan (HMC) biopolymer extracted from crab shells. The combination of cationic and hydrophobic functionalities into the HMC facilitates synergistic emulsion stabilization with negatively charged halloysite clay nanotubes (HNT). The bulk emulsion system and the oil-water interfacial structure are characterized to elucidate the synergistic roles of HMC and HNT in oil emulsification. The design of a ternary, mixed emulsifier system with inorganic tubular micelle based architecture is further demonstrated by loading the surfactant, Span 80, into the lumen of HNT.
Data Parameters and Units:
Note: All the file name refers to figures and tables of the associated paper (in review): Hydrophobically Modified Chitosan Biopolymer Connects Halloysite Nanotubes at the Oil-Water Interface for Synergistic Emulsion Stabilization.
Figure 1. Structure of the halloysite nanotube (HNT), representative repeat units of hydrophobically modified chitosan (HMC) biopolymer and sorbitan monooleate (Span 80) surfactant.
Figure 2. 1H NMR spectra of native chitosan and hydrophobically modified chitosan (HMC).
Figure 3. (a – d) Optical microscopy images of dodecane-in-water emulsions stabilized by increasing amounts of HMC (magnification used for optical microscopy in figure 3a - 3d was 10x/0.30 on a Nikon Eclipse LV100 Microscope). The insets are photographs of vials containing the emulsions. Scale bars = 100 μm.
File Figure 3e Average droplet sizes and emulsion stability to coalescence.xlsx: Concentration of Hydrophobically Modified Chitosan (HMC); Average Droplet Diameter (microns); Fraction of oil resolved on centrifugation (Trial 1; Trial 2).
Figure 4. (a) Zeta potential of hydrophobically modified chitosan (HMC) solutions and dodecane-in-water emulsions stabilized by HMC (Zeta potential in mV) (b) Cryo-SEM images of dodecane-in-water emulsions stabilized by HMC. Images (i) to (iv) in panel b are in increasing order of magnification; 800x, 1300x, 5000x and 10000x respectively.
File Table 1 Zeta potential HMC and HNT mixtures.xlsx: HMC Concentration; Zeta Potential (mV) of HMC and HNT mixtures.
File Figure 4a Zeta potential of hydrophobically modified chitosan HMC solutions and emulsions stabilized by HMC.xlsx: HMC Concentration (wt%); Zeta potential of hydrophobically modified chitosan (HMC) solutions (millivolts); Zeta potential of dodecane-in-water emulsions stabilized by HMC (millivolts).
Figure 5a. Photographs showing colloidal stability of halloysite nanotubes (HNT) as a function of hydrophobically modified chitosan (HMC) concentration. Figure 5b is turbidity (transmittance) measurements over time at 400nm (Transmittance in %, Time in seconds). The optical path length for the transmittance measurements was 10mm.
Figure 5b Colloidal stability of HNT_as a function of HMC_concentration_turbidity measurements over time at 400nm.xlsx: Time (seconds); HMC Concentration; Transmittance (%): HNT concentration fixed at 0.1 wt%
Figure 6a-6f. SEM images of HNT (a,b) and HNT with adsorbed HMC (c-f). Magnification used for SEM images 6a, 6b, 6c, 6d, 6e, 6f are 9000x, 70000x, 11000x, 25000x, 40000x and 110000x respectively; SEM voltage 3kV, working distance 8 mm). Figure 6g. Photographs showing contact angle of water in an external dodecane phase on the surface of native HNT and HNT with adsorbed HMC (g). Compressed tablets were made from dried particles initially recovered by centrifugation from systems with HMC to HNT mass ratios of 0 (i), 0.05 (ii), 0.1 (iii) and 0.25 (iv) respectively.
Figure 7a – 7d. Optical microscopy images of dodecane-in-water emulsions stabilized by 0.1wt% HNT and increasing HMC concentrations of 0wt% (a), 0.01wt % (b), 0.025wt % (c) and 0.05wt % (d) respectively (magnification used for optical microscopy in figure 6a was 10x/0.30 on a Nikon Eclipse LV100 Microscope); Figure 7e. Emulsion stability to coalescence and average droplet sizes (µm).
File Figure 7e Emulsion stability to coalescence and average droplet sizes_emulsions stabilized by HNT and HMC.xlsx: HMC concentration; Fraction of oil resolved on centrifugation (Set 1; Set 2); Average droplet size (microns).
File Table 2. Zeta potential emulsions stabilized by HMC and HNT.xlsx: HMC Concentration; Zeta Potential (mV) of oil-in-water emulsions stabilized by HMC and HNT.
Figure 8. Cryo-SEM images of dodecane-in-water emulsions stabilized by the HNT and HMC. Panels (a) to (f) are in increasing order of magnification; 45x, 400x, 1100x, 2000x, 25000x and 50000x respectively.
Figure 9. (a) FTIR spectra of native HNT and Span 80 loaded HNT (Absorbance in au, wavenumber in 1/cm). The inset shows a representative TEM image of a Span 80 loaded HNT (TEM voltage = 300 kV, magnification = 90000x). (b) Dynamic interfacial tension measurements for dodecane–water interface laden with HMC (green squares), HMC/HNT (blue circles), and HMC/Span 80 loaded HNT (red triangles). The HMC, HNT and Span 80 loaded HNT concentrations in the aqueous droplet were 0.05 wt%, 0.1 wt% and 0.1 wt% respectively (interfacial tension in mN/m; time in seconds). The inset shows optical micrograph of crude oil in saline water emulsion prepared with span 80 loaded HNT (0.1 wt%) and HMC (0.05wt%). Scale bar is 100μm, magnification used for optical microscopy was 10x/0.30 on a Nikon Eclipse LV100 Microscope.
File Figure 9a FTIR spectra of native HNT and Span 80 loaded HNT.xlsx: Halloysite (HNT) [Wavenumber (1/cm); Absorbance (au)]; Span 80-loaded Halloysite (HNT) [Wavenumber (1/cm); Absorbance (au)].
Figure 9b Dynamic interfacial tension measurements for dodecane water interface.xlsx: Time (seconds); Interfacial Tension , mN/m [HMC; HMC/HNT; HMC/Span 80 loaded HNT].
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