The impact of surfactants on the stability and thermal conductivity of graphene oxide de-ionized water nanofluids

Abstract

The effects of three different surfactants were analyzed on the stability and thermal conductivity of GO/de-ionized water nanofluids. One surfactant was cationic, cetyltrimethyl ammonium bromide (CTAB), one was anionic, sodium dodecyl sulfate (SDS), and one was nonionic, TritonX-100 (TX-100). These were added to synthesized graphene oxide (GO) prepared in de-ionized water at different concentrations (0.01, 0.05, 0.1, 0.15, 0.2, and 0.25 mass%). The transient hot-wire technique was employed to measure the thermal conductivity of all nanofluids at 20–40 °C. The stability of the GO/de-ionized water nanofluids without a surfactant was better than that of nanofluids with a surfactant. The stability and dispersion of the nanofluid with SDS were considerably better than nanofluids with the other two surfactants. All nanofluids without a surfactant had higher thermal conductivity than de-ionized water at all temperatures. An increase in the GO concentration from 0.01 to 0.2 mass% improved thermal conductivity by 3.05 and 22.03% at 20 °C, respectively. A further increase to 0.25 mass% caused a 23.73% increase in thermal conductivity.