Abstract:

The dataset shows details of the optical micrographs and cryo-scanning electron micrographs of halloysite stabilizing the oil-water interface. Transmission electron microscopy is used to show images of native halloysite clay nanotubules (HNT) and HNT loaded with dioctyl sulfosuccinate sodium (DOSS). Additional data reported include the mass of HNT with various DOSS loadings and droplet diameter with various HNT concentrations. Experiments included measuring the concentration of DOSS and Tween 80 released into saline water as characterized by methylene blue active substances and cobalt thiocyanate active spectrophotometric methods, respectively. Droplet size and interfacial tension was measured for dodecane-saline water emulsions stabilized by HNT , HNT and DOSS and HNT and Tween 80. This data supports the paper "Release of Surfactant Cargo from Interfacially Active Halloysite Clay Nanotubes for Oil Spill Remediation" published in LANGMUIR doi: 10.1021/la503687b.

Suggested Citation:

John, Vijay. 2016. Dataset for: Release of Surfactant Cargo from Interfacially Active Halloysite Clay Nanotubes for Oil Spill Remediation. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7WS8R7P

Publications:

Owoseni, O., Nyankson, E., Zhang, Y., Adams, S. J., He, J., McPherson, G. L., … John, V. T. (2014). Release of Surfactant Cargo from Interfacially-Active Halloysite Clay Nanotubes for Oil Spill Remediation. Langmuir, 30(45), 13533–13541. doi:10.1021/la503687b

Purpose:

Our objective in this work is to encapsulate surfactants representative of COREXIT 9500, the commonly used dispersant in oil spill remediation, into the tubular voids of halloysite. We show that halloysite stabilizes oil-in-water emulsions and subsequently releases the surfactants, thereby reducing the interfacial tension significantly, allowing much smaller droplets to form, leading to enhanced dispersion of oil.

Data Parameters and Units:

Figure 1a-f: Figure 1. Optical microscopy images of dodecane-in-water emulsions showing the interfacial activity of HNT. HNT concentrations in water were 0.01 wt % (a), 0.05 wt %(b), 0.1 wt %(c), 0.2 wt %(d), 0.5 wt %(e), and 1 wt %(f), respectively. Figure 2. HNT concentration (wt%), emulsion stability (fraction of oil resolved on centrifugation), and average droplet size (μm). Figure 3a-h; Figure 9a-dcryo-scanning electron microscopy of oil-in-water emulsions -- Cryo-SEM images show that Halloysite clay nanotubes assemble in a side-on orientation at the oil–water interface and form networks on the interface through end-to-end linkages. -- Scale bars = 1 - 300 μm. Figure 4. Schematic of a cylindrical particle in a side-on orientation at a planar oil–water interface. Figure 5. Free energy of detachment with number of contacting cylindrical particles. Number of particles Radius of Cylindrical Particle (nm) Figure 6: Mass loss (%), temperature (degrees celcius) Figure 7: polyoxyethylene (20) sorbitan monooleate (Tween 80), concentration (mg/L), Dioctyl sulfosuccinate sodium salt (DOSS) concentration (mg/L), Time (hours) Figure 8 surfactant loading in HNT, Average emulsion droplet size (μm), insets-Optical microscopy images of dodecane-in-water emulsions (scale 100 μm) Figure 10: Dispersant to Oil Ratio, Crude Oil/Water IFT (mN/m); HNT loaded with DOSS, Span 80 and Tween 80 (12.4wt%); HNT loaded with DOSS and Tween 80 (11.0wt%); HNT loaded with DOSS (11.9 wt %)

Methods:

Emulsion Preparation: The nanotubes were uniformly dispersed in water by ultrasonication (Cole-parmer 8890) for 1 minute. Dodecane was then added to the nanotube dispersion at a dodecane to water ratio of 1:3. The emulsions were then prepared by vortex mixing at 3000rpm (Thermolyne Maxi Mix II) for 2 min. Optical Microsscopy: A small aliquot of the oil-in-water emulsion was removed using a Pasteur pipet and diluted with water prior to imaging on a Leica DMI REZ optical microscope. The images were analyzed using Image ProPlus v. 5.0 software to obtain the droplet sizes. Cryo-Scanning Electron Microsocopy: The structure of drop interfaces were imaged by Cryo-scanning electron microscopy (Cryo-SEM) imaging on a Hitachi S-4800 field emission Scanning Electron Microscope operated at a voltage of 3 kV and a working distance of 9 mm. The emulsion sample was first plunged into liquid nitrogen, followed by fracturing at −130 °C using a flat-edge cold knife and sublimation of the solvent at −95 °C for 5 min. The sample was sputtered with a gold–palladium composite at 10 mA for 88 s before imaging.

Instruments:

cryo-scanning electron microscopy, optical microscopy, rheology and scanning electron microscopy

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