Effect of Dispersion Stability on Electrorheology of Water-Based ZnO Nanofluids

Abstract

Untreated nanoparticles possess huge surface areas compared to their mass, resulting in strong inter-particle interactions in saline water. This induces a strong tendency of particles' agglomeration, rapid sedimentation and consequently reduced the mobility of nanoparticles in the aquatic environment, which ultimately lowering the effective viscosity of the nano system. This study aimed to investigate the effect of stabilizers on the stability of dielectric nanofluid, to provide a better electrorheological characteristic for Nano-EOR purposes. In this research, zinc oxide (ZnO) was employed as dielectric nanoparticles under various nanoparticles concentration (0.1, 0.05, 0.01 wt. %). Anionic surfactants (SDS, SDBS, and Oleic acid) were compared in an attempt to prepare the homogeneous dispersions with long-term stability at high temperature (~ 95°C). The laboratory experiments were designed to evaluate the sedimentation behavior of nanoparticles using visualization method; whereas UV-vis spectrophotometry was employed to quantitatively characterize the stability of the nanoparticle dispersions. Further, dynamic light scattering (DLS) were also used to determine the size distribution of dispersed nanoparticles. The stabilized nanofluids were then subjected for measuring of electrorheological behavior using a rotating viscometer attached to a custom-built solenoid coil. From the experimental results, it is concluded that the most stable aqueous dispersion of ZnO nanoparticles is obtained at 0.1 wt. % with the aid of 0.025 wt. % SDBS under the conditions of 60 min of ultrasonication, adjusted at the pH value of 2. The ZnO/SDBS dispersion having a hydrodynamic size of 240.9 nm exhibits extreme stability at high temperature of 95°C, with the supernatant ZnO concentration decreasing only 19% compared with a decrease of 100% for the bare ZnO/Brine system. The rheological measurements indicated that all the nanofluids exhibit pseudoplastic (shear thinning) behavior. While the 0.1 wt. % ZnO/SDBS dispersion provide an enhancement in the relative viscosity of nanofluid up to 11% compared to brine as a basefluid, indicating the role of stability to achieve an electrorheological effect by activating dielectric ZnO nanoparticles. Additionally, the viscosity ZnO nanofluid increased with the increase of particle concentration under an applied field, which shows the strong dependence of viscosity on particle loading. The combined treatment with the surfactant, pH and ultrasonication is recommended to enhance the electrorheological characteristics of ZnO nanofluid. Hence, the mobility of a stabilized nanofluid can be efficiently controlled by regulating the applied field for EOR purposes.

Synthesis of Zno Nanoparticles and their Nanofluid Stability in the Presence of a Palm Oil-Based Primary Alkyl Sulphate Surfactant for Detergent Application

“…It can be seen that the nanofluid with a ZnO:palmPAS ratio of 1:9 has good stability, because the surfactant added into the nanofluid has not yet reached its saturation point. A previous study documented that the addition of excessive free-surfactant led to lower nanofluidic stability (Adil et al, 2016). The effect of the calcination of the nanoparticles on nanofluidic stability is illustrated in Figure 5.…”

“…In the same report, it was also suggested that adding SDS improves stability around alkaline pH. Brine was used in another study with the addition of sodium dodecyl sulfate, sodium dodecylbenzenesulfonate and oleic acid at pH 2, and it was revealed that all the surfactants were able to improve the stability of the nanoparticles (Adil et al, 2016).…”

Recrystallization techniques for the synthesis of ZnO nanorods: an in situ process for carbon doping and enhancing the dispersion concentration of ZnO nanorods

“…14 Several methods have been utilized to prevent such aggregation and produce stable ZnO nanoparticles, including covering ZnO nanoparticles by organic molecules [15][16][17] or inorganic SiO 2 shells 18 and coating 19 the nanoparticle surface by polymerization. Alternatively, other efforts have been undertaken to improve the dispersion stability of ZnO in an organic solvent or in the aqueous phase by using a surfactant, 20 polymer 8,21,22 phosphate, 23 inositol hexakisphosphate, 24 organic matter, [25][26][27] or oleic acid, 6,28 a combination of a polymer and exfoliating agent such as zirconium phosphate; 29 ionic materials; 30 and the controlled combined effect 31 of pH and ionic strength. However, surface modication has a signicant impact on various properties; 4,5 further, it is useful to obtain a stable ZnO solution that allows the dispersion of ZnO nanoparticles in organic and water 7 solvents.…”

A State-of-the-Art Review of Nanoparticles Application in Petroleum with a Focus on Enhanced Oil Recovery

“…However, Ogolo et al [12] found that ZnO dispersed in brine and water caused permeability reduction due to the agglomeration of ZnO NPs into larger particles, which blocked the pore throats of the core. Since stability is one of the key factors for a successful EOR application, Adil et al [135] performed further studies on the stability of ZnO NPs dispersed in water by using different anionic surfactants as stabilizers with various NPs concentrations. They found that 0.1 wt % ZnO NPs stabilized with 0.025 wt % sodium dodecyl benzenesulfonate (SDBS) have the highest stability at 95 • C with viscosity enhancement up to 11%.…”