Importance of interfacial and rheological properties in the suppression of uniform deposition to coffee ring pattern of zinc oxide nanofluids in the presence of anionic surfactants

Nanofluids have gained more importance in the different process industries because of the enhanced wettability, thermal properties, and nature to form a specific self-assembly pattern. This study shows the wettability nature of three commercial surfaces by ZnO nanofluids with and without synthetic anionic sodium dodecyl sulfate (SDS) surfactant. The wettability nature of a particular solid surface is influenced by the chemical nature as well as the size and concentration of nanomaterial in nanofluids. The ZnO nanofluids do not affect the wetting property of the base fluid because of the hydrophilic nature of the ZnO nanoparticles which prefers the particle to stay in the bulk for better stability. Though additionally in the presence of anionic surfactant in ZnO nanofluids, it is showing the synergetic effect and effectively increases the wettability properties of the base ZnO nanofluids. The rheological properties of the ZnO nanofluids are also affected in surfactant media, it deviates from the Newtonian to slightly non-Newtonian behavior in the presence of synthetic anionic SDS surfactant. But most importantly, the presence of the surfactant molecules influences the effective forces which directly suppress the uniform particles deposition toward the specific coffee ring pattern. This study will give a clear idea about the reason behind the formation of the coffee ring pattern of the ZnO nanoparticles from the evaporating droplet. The result of this study concludes that the application of the nanofluids can be enhanced in oil recovery or as drilling fluid in the presence of surfactant because of the effective decrease in viscosity.