Surface tension of Ag NPs-rGO based hybrid nanofluids

Abstract

A novel type of hybrid nanoparticles/nanofluid is synthesized, characterized and prepared by suspending silver nanoparticles (Ag) and reduced graphene oxide sheets (rGO) in water (W) and water-ethylene glycol (W + EG) mixture. Experiments are carried out to determine the effects of the base fluid, concentration and temperature on the surface tension of solutions. Du-Noüy ring method is employed for the measurements. The surface tension of Ag NPs-rGO nanofluids is measured at temperatures ranging from 293.15 to 323.15 K and different concentrations of nanoparticles (0.050, 0075 and 0.10 wt%) respectively. The results show that the surface tension of the hybrid nanofluids is strongly influenced on presence/absence of sodium carboxymethyl cellulose (CMCNa) surfactant as well as the nanoparticles concentrations and temperatures. The surface tension is reduced by adding the surfactant to both base fluids and increasing temperature. An increase in concentration leads to increasing surface tension by nearly 7.5% and 2.4% with 0.10 wt% in concentration at 293.15 and 323.15 K, respectively for Ag NPs-rGO/water nanofluid. Similar for Ag NPs-rGO/water-ethylene glycol nanofluid, the increase in surface tension is 9.5% and 8.25% for the same conditions of concentration and temperature. These findings are promising for the use of Ag NPs-rGO nanofluids in boiling heat transfer.