Effect of Various Surfactants on the Viscosity, Thermal and Electrical Conductivity of Graphene Nanoplatelets Nanofluid

The effects of surfactants on the stability and thermophysical properties of graphene nanoplatelets nanofluids are experimentally studied at different temperatures. Graphene nanoplatelets (GNP) nanofluids were prepared with various surfactants, including sodium dodecylbenzene sulfonate (SDBS), sodium dodecyl sulfate (SDS), Gum Arabic (GA), and Tween 80 at different GNP-surfactant ratios (2:1, 1:1, and 1:2). The best dispersion and stabilization over 2 weeks was found to be with a GNP-surfactant ratio of 2:1 for SDBS-based nanofluids and 1:1 for nanofluids with other surfactants. A comparative study of the effects of the different surfactants on the electrical conductivity, pH, thermal conductivity, and viscosity was carried out. The study observed that all nanofluids’ electrical conductivity and thermal conductivity are augmented at elevated temperatures while the pH and viscosity deteriorate at higher temperatures. The electrical conductivity measurements of the GNP nanofluids show that SDBS addition contributes the highest enhancement of 154.33 % compared to water. This was followed by SDS, GA, and Tween 80-based nanofluid, which has an electrical conductivity enhancement of 153.25 %, 21.48 %, and 2.83 %, respectively. In comparison to water, the thermal conductivity results revealed that SDBS, GA, SDS, and Tween 80-based nanofluid has a maximum enhancement of 5.50 %,5.66 %, 6.45 %, and 8.96 %, respectively, at 45 °C. This shows that a higher thermal conductivity enhancement is achieved using Tween 80 as the dispersant. The experimental results further revealed that the viscosity of the nanofluids greatly increased with the use of GA compared to other surfactants. Compared to water, a maximum viscosity increase of 5.79 %, 17.54 %, 19.30 %, and 22.81 % was obtained for SDBS-GNP, GA-GNP, SDS-GNP, and Tween 80-GNP, respectively at 55 °C.