Preparation and Thermal Stability of Oil-based Au Nanofluids

Abstract

Two cationic surfactants,N-cetyl-N-(hydroxyethyl)-N,N-dimethyl ammonium bromide(CHDAB) and 1,4-bis(cetyldimethylammonium) propane dibromide(G16-4-16),were used as surface-modified reagents for preparation of hydrophobic gold nanoparticles from reduction of HAuCl4 with KBH4 in mixture of petroleum ether/n-butanol/H2O.The results show that gemini surfactant G16-4-16 is better for coating and dispersing,and the gold nanoparticles coated by the gemini surfactant G16-4-16 have a narrow size distribution with an average diameter of 5.2 nm.Stable nanofluids containing gold nanoparticles with hydrocarbon(toluene) as base liquids were prepared.The thermal stability of the nanofluids as a function of time was monitored using UV-Vis absorption method.It is shown that the gold nanofluid has good thermal stability,which has a stable time of 20 h at 130 ℃.The thermal conductivity of the gold nanofluids was performed by point heat source method.The enhancements of thermal conductivity of the gold nanofluids containing 1.5%(mass fraction) gold nanoparticles can reach 17%.