Abstract:
In this study individual halloysite nanotubes (HNTs) pre-loaded with Tween 80 surfactant were coated with a thin layer of long chain hydrocarbon wax (Paraffin wax, C20 – C40) with a high melting point. In addition, there was an extensive characterization of the morphology of Pristine halloysite nanotubes (HNTs), Tween 80 loaded halloysite nanotubes (S-HNTs) and Waxcoated, surfactant-loaded halloysite nanotubes. This dataset supports the publication: Farinmade, A., Ojo, O. F., Trout, J., He, J., John, V., Blake, D. A., … Bose, A. (2019). Targeted and Stimulus-Responsive Delivery of Surfactant to the Oil-Water Interface for Applications in Oil Spill Remediation. ACS Applied Materials & Interfaces. doi:10.1021/acsami.9b17254.
Suggested Citation:
Azeem Farinmade, Olakunle Francis Ojo, James Trout, Jibao He, Vijay John, Diane A. Blake, Yuri M. Lvov, Donghui Zhang, Duy Nguyen and Arijit Bose. 2019. Dataset for: Targeted and Stimulus-Responsive Delivery of Surfactant to the Oil-Water Interface for Applications in Oil Spill Remediation. Distributed by: Gulf of Mexico Research Initiative Information and Data Cooperative (GRIIDC), Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/MDV8KEG6
Data Parameters and Units:
Dataset consists of one Excel file (Data.xlsx) and several Tiff and JPG files (Figures 1-6 and Figures S5-S6). The headers in the Excel file are - Contact Angle (◦), Temperature (◦C), Weight %, Time (h), Conc. (mg/ml), Time (Mins), Interfacial Tension (mN/m), Droplet count, Droplet diameter (μm), Wavenumber (cm-1), Intensity (A.U.), % wax dissolution, and Length (nm). Please note that all the figure # in the data file name refers to figure # in the associated publication Farinmade et al., 2019.
Figure 1a: Chemical structures of Halloysite nanotubes and Tween 80 surfactant
Figure 1b: Schematic showing the procedures for loading halloysites with surfactants and coating with wax as well as a photograph of the final products.
Figure 2(a-f): Scanning electron Microscopy images of bare HNTs, S-HNTs and WS-HNTs. SEM imaging was carried out using a Hitachi S-4800 Field emission scanning electron microscope operated at 3kV at a 3mm working distance. The samples were dispersed in ethanol and dropped on a sample holder followed by carbon coating to improve imaging by dissipating charging artifacts.
Figure 3(a-c): Transmission electron Microscopy of bare HNTs, S-HNTs and WS-HNTs. TEM imaging was carried out using an FEI G2 F30 Tecnai transmission electron microscope operated at 300 kV at room temperature. The samples were briefly dispersed in ethanol and dropped on the carbon-coated copper TEM grid and allowed to dry off prior to imaging.
Figure 3d (I and II): Contact Angle Measurement for bare HNTs and Wax coated HNTs. Each particulate sample (Pristine HNT and W-HNT) was compacted in a pellet die and pressed into a 13 mm disk pellet with about 1 mm thickness using a hydraulic press (Carver Laboratory Press). The contact angle was measured by placing the sample pellet in a goniometer (Ramé-Hart, model 250) and a 5 μL water droplet was dispensed on the sample using an automatic Ramé-Hart dispenser. Following equilibration, the three-phase contact angle was measured by DROPimage Advanced Software.
Figure 4a: Thermogravimetric analysis (TGA) of bare HNTs, S-HNTs and WS-HNTs. To determine the weight percent of surfactant loading and a wax coating, thermogravimetric analysis was performed using a TA instrument TGA Q500 thermogravimetric analyzer, operated at 5^o^C/min from 26^o^C to 720^o^C in a nitrogen environment.
Figure 4b: Tween 80 release kinetics from S-HNTs and WS-HNTs. The concentration of Tween 80 surfactant released in saline water was analyzed using the cobalt thiocyanate active substances (CTAS) UV-Vis Spectroscopy technique for determining Tween 80 in part per million (ppm) concentration. A UV-vis spectrophotometer (Shimadzu UV-1700) was used to measure the absorbance of the chloroform phase containing the cobalt thiocyanate−polyethoxylate complex at 620 nm. The concentration of Tween 80 for each sample analyzed was then extrapolated from an absorbance vs. concentration calibration curve of known concentrations of Tween 80.
Figure 5a: Time-dependent interfacial tension measurements. Interfacial tension was measured using the pendant drop technique on a standard goniometer (Ramé-Hart, model 250). 1mg/ml of particle suspension was prepared in saline water at room temperature. 20 μL of the suspension containing particles was drawn from the vial with a flat tip needle by an automatic Ramé-Hart dispenser. The needle was then plunged into a glass cuvette containing 5 ml of dodecane (oil phase) and 15 μL of the WS-HNT particles dispersed in water was injected. Drop shape analysis (DROPimage Advanced software) was used to determine the change in water-dodecane interfacial tension over time
Figure 5b: Emulsion droplet optical microscopy. Aliquots of the prepared dodecane in water emulsion were pipetted onto a glass slide for imaging under a Nikon eclipse LV100 optical microscope. The droplet size analysis was done using the ImageJ (open source) graphic analysis software and the average droplet size obtained from a distribution of 200 droplets
Figure 6(a-f): Cryo- Scanning electron Microscopy images of emulsions formed by W-HNTs and WS-HNTs. Cryo-SEM was employed to characterize the dodecane-water emulsions using a Hitachi S-4800 Field Emission Scanning Electron Microscope operated at 3 kV. To prepare the emulsion samples for imaging, small aliquots of the dodecane in water emulsion stabilized by W-HNT or WS-HNT were vitrified using liquid nitrogen. The frozen emulsion sample was then fractured at -130^o^C with the aid of a cold flat-edged knife followed by sublimation at -95^o^C for 10 minutes to expose droplets that are clearly imaged
Figure S1: X-ray Diffraction (XRD) patterns for Pristine HNTs, S-HNTs and WS-HNTs. X-ray powder diffraction (XRD) was carried out on a Siemens D500 X-ray diffractometer, using Cu Kα radiation at 1.54 Å, to determine the crystalline properties of bare HNTs, S-HNTs and WS-HNTs
Figure S2: Fourier Transform Infrared spectroscopy spectra of Pristine HNTs, S-HNTs and WS-HNTs. Fourier Transform Infra-Red (FTIR) spectroscopy was carried out using a Thermo Nicolet Nexus 670 FTIR spectrometer. For the FTIR analysis, each particulate sample was imbibed into Potassium bromide (KBr) powder and pressed into a thin transparent pellet prior to FTIR analysis
Figure S3: Proof of Tween 80 encapsulation by wax coating. The concentration of Tween 80 surfactant released in saline water was analyzed using the cobalt thiocyanate active substances (CTAS) UV-Vis Spectroscopy technique for determining Tween 80 in part per million (ppm) concentration. A UV-vis spectrophotometer (Shimadzu UV-1700) was used to measure the absorbance of the chloroform phase containing the cobalt thiocyanate−polyethoxylate complex at 620 nm. The concentration of Tween 80 for each sample analyzed was then extrapolated from an absorbance vs. concentration calibration curve of known concentrations of Tween 80
Figure S4: Gas chromatography wax dissolution analysis. The concentration of wax dissolved in dodecane was analyzed by gas chromatography (Agilent Technologies 7820A). The elution time for dodecane occurs at about 3.9 minutes while peaks for paraffin wax appear from 13 to 30 minutes due to the multi-component nature of paraffin wax used. The most intense peak for paraffin wax was observed at 17.3 minutes and was used as the reference. Wax concentration in dodecane for each sample was extrapolated from a calibration curve of peak intensity vs paraffin wax concentration for known amounts of paraffin wax dissolved in dodecane.
Excel document “data.xlxs”: Tab “Figure 3d” contains the three-phase contact angles (in degrees) of bare halloysites. Tab “Figure 3d(ii)” contains the three-phase contact angle (degrees) of the Wax coated HNTs. Tab “Figure 4a” contains the Thermogravimetric Analysis (TGA) of Weight loss for Pristine HNTs, Surfactant loaded HNTs (S-HNTs) and Wax-coated, Surfactant-loaded HNTs (WS-HNTs). Tab “Figure 4d” contains Release kinetics of Tween 80 surfactant from Surfactant loaded HNTs (S-HNTs) and Wax-coated, Surfactant-loaded HNTs (WS-HNTs) in 0.6M saline water conducted in three data sets each. Tab “Figure 5a” contains Time-dependent water/dodecane Interfacial tension measurements for systems containing Tween 80 surfactants only, Wax coated HNTs (W-HNT), Wax coated and Surfactant-loaded HNTs (WS-HNTs) and Wax coated HNTs with surfactants adsorbed to its external surface. Tab “Figure 5b” contains Droplet size distribution for water-dodecane emulsions stabilized by Wax coated HNTs (W-HNTs). Tab “Figure 5b(ii)” contains Droplet size distribution for water-dodecane emulsions stabilized by Wax coated and surfactant loaded HNTs (WS-HNTs). Tab “Figure S1” contains the X-ray Diffraction (XRD) analysis of Paraffin wax, Pristine HNTs, Surfactant (Tween 80) loaded HNTs (S-HNTs) and Wax coated, surfactant loaded HNTs (WS-HNTs). Tab “Figure S2” contains Fourier Transform Infrared (FTIR) analysis of Pristine HNTs, Surfactant (Tween 80) loaded HNTs (S-HNTs), and Wax coated, surfactant loaded HNTs (WS-HNTs). Tab “Figure S3” contains Plot showing the removal of excess tween 80 from wax-coated HNTs loaded with Tween 80 surfactant (WS-HNTs) by washing and the release of encapsulated tween 80 upon heating and melting of the wax coating. Tab “Figure S4” contains a graph showing the Rate of Paraffin wax dissolution from wax-coated halloysite into dodecane analyzed using gas chromatography. Tab “Figure S5a” contains 3 phase contact angle measurement for bare HNTs with dodecane as an external phase. “Figure S5b” contains 3 phase contact angle measurement for wax coated HNTs with dodecane as an external phase. “Figure S6a” contains a plot showing the size distribution of the external diameter of bare HNTs obtained from SEM images. “Figure S6b”contains a plot showing the size distribution of the external diameter of surfactant loaded HNTs obtained from SEM images. “Figure S6c” contains a plot showing the size distribution of the external diameter of wax-coated and surfactant loaded HNTs obtained from SEM images. “Figure S7a” contains the droplet size distribution for water-dodecane emulsions stabilized by Wax coated and surfactant loaded HNTs (WS-HNTs). “Figure S7b” contains a Plot showing the size distribution of the external diameter of wax-coated and surfactant loaded HNTs after contact with crude oil obtained from SEM images.
Tiff and JPEG figures: Figure 1a shows the chemical structures of halloysites and Tween 80 surfactant. Figure 1b shows the schematic for loading HNTs with surfactants and coating with wax as well as photographs of HNTs, S-HNTs and WS-HNTs. Figure 2a and 2b show SEM images of bare HNTs at different magnifications. Figure 2c and 2d show SEM images of surfactant loaded HNTs (S-HNTs) at different magnifications. Figure 2e and 2f show SEM images of wax-coated and surfactant loaded HNTs (WS-HNTs) at different magnifications. Figure 3a shows the high-resolution TEM image of bare HNT. Figure 3a inset shows a higher magnification TEM image of bare HNT to visualize the clear lumen. Figure 3b shows TEM images of surfactant loaded HNTs (S-HNTs). Figure 3b inset shows a higher magnification TEM image of S-HNT to visualize the filled lumen. Figure 3c shows TEM images of wax-coated and surfactant loaded HNTs (WS-HNTs). Figure 3c inset shows a higher magnification TEM image of WS-HNT to visualize the wax coating. Figure 3d shows water contact angle measurements for (I) pristine HNTs (II) Wax coated HNTs to show the effects of wax coating on the wetting properties. Figure 5b shows optical micrographs of emulsions stabilized by (I) W-HNTs and (II) WS-HNTs. Figures 6a-d shows cryo-SEM images of emulsion stabilized by W-HNTs at different magnifications. Figure 6e-f cryo-SEM images of emulsion stabilized by W-HNTs at different magnifications. Figure 6f inset shows higher magnification of cryo-SEM images of emulsion stabilized by WS-HNTs to clearly visualize the HNTs at the interface. Figures S5a shows a three-phase contact angle for pristine HNTs with n-dodecane as the external phase. Figures S5b shows three-phase contact angle for Wax coated HNTs with n-dodecane as the external phase. Figure S7a shows optical micrograph of Anadarko crude oil emulsions formed by WS-HNTs. Figure S7b shows an SEM image of WS-HNTs recovered after the formation of crude-oil in water emulsions. Figure S7b inset shows a higher magnification SEM image of WS-HNTs recovered after the formation of crude-oil in water emulsions.
Methods:
Characterization of the morphology of Pristine halloysite nanotubes (HNTs), Tween 80 loaded halloysite nanotubes (S-HNTs) and Waxcoated, surfactant-loaded halloysite nanotubes (WS-HNTs) was performed with Transmission Electron Microscopy (FEI Tecnai G2 F30 Twin transmission electron microscope operated at 300 kV) and Scanning Electron Microscopy (Hitachi S-4800 Field emission scanning electron microscope operated at 3 kV). Thermo Nicolet Nexus 670 FTIR spectrometer was used to carry out Fourier Transform Infra-Red (FTIR) spectroscopy.
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