Zetasizer nano series nano zs

Zeta-potential measurements were performed on ZetaSizer nano series - Nano-ZS (Malvern Instruments Ltd., United Kingdom). The instrument measures the direction and velocity of a particle in an applied electrical field via phase analysis light scattering and laser Doppler velocimetry. The calculated electrophoretic mobility is converted into zeta potential values using the Smoluchowski model. Before measuring the rock particles or emulsions in surfactants solutions, the zeta-potential of surfactant solutions was determined to make sure the results of rock particles or emulsions will not be interfered by surfactants aggregates.

Particle size expressed as hydrodynamic diameter and size distribution expressed as polydispersity index (PdI) were determined using dynamic light scattering (DLS), while ζ-potential measurements were based on electrophoretic light scattering (ELS). All measurements were conducted in a ZetaSizer Nano series Nano-ZS (Malvern Instruments Ltd., Malvern, UK) equipped with a He-Ne Laser beam, set up in a wavelength of 633 nm and backscattering angle of 173°. Settings for ζ-potential measurement contained an average of 100 runs with the phase analysis light scattering mode (PALS) and equilibration temperature of 25 °C. NPs dispersion in water was prepared by dispersing 5 mg of NPs in 10 mL of water. All measurements were carried out in triplicate.

Positive or negative charges of polymeric solutions were measured by laser Doppler electrophoresis using a using a Zetasizer nanoseries Nano ZS (Malvern Instruments Ltd., Malvern, UK). Data analysis of Zeta potential is presented as mean standard deviation of three samples (with ten runs for each sample).

Size distribution was determined with Dynamic Light Scattering (DLS) using a Zetasizer Nanoseries Nano-ZS (Malvern Panalytical, Malvern, UK) at 23 °C. Briefly, a sample of nanoparticles dissolved in citric acid (0.3%) was analysed for three sessions of 90 runs of 90 s each. SEM analysis was performed on a 10 µL sample.

A Malvern Mastersizer MS 3000 (Malvern Instruments Ltd., Cambridge, UK) was employed to evaluate the droplet sizes and polydispersity indexes. ζ-potential values were estimated by employing a particle electrophoresis instrument (Zetasizer Nanoseries Nano-ZS, Malvern Instruments, Worcestershire, UK). Different emulsions were diluted 100 times with citric buffer before measurement. All measurements were performed in triplicate and reported values were given as average ± standard deviation. At Φ_I = 0.038, the average droplet size was 478 ± 58 nm. The polidispersity index (PDI) was 0.22, suggesting that nanoemulsions were essentially monodisperse. The ζ-potential of the nanoemulsions was −15 mV, according to the non-ionic nature of the surfactant Tween 80. Note that the destabilization process was not observed by the naked eye for more than 3 months. Figure 1 shows a TEM photograph of the nanoemulsions prepared in this work.

The intensity-averaged particle diameters and polydispersity indices of the NPs were determined by dynamic light scattering (DLS) with 173° backscatter detection. The electrophoretic mobility values, measured by laser Doppler velocimetry, were converted to zeta potential by the Smoluchowski equation. Both DLS and LDV measurements were performed on a Zetasizer nano series Nano-ZS fitted with a 633 nm laser (Malvern Instruments, Malvern, UK). The measurements were performed at an NP concentration of approximately 0.3 mg/mL, obtained by 30-fold dilution of 10 mg/mL dispersion with MilliQ water. Each analysis was carried out at 25 °C in triplicate.
Particle morphology was evaluated by scanning electron microscopy (SEM). A strip of double-sided carbon tape was placed on a SEM stub. A small quantity of freeze-dried NPs was gently spread across the surface of the tape, and compressed air was used to remove loose particles. Samples were sputter-coated with carbon for 20 s and viewed under a Hitachi S-4800 scanning electron microscope (Hitachi High-Technologies Corporation, Hitachi, Japan).