Long-term colloidal stability of graphene oxide aqueous nanofluids

Abstract

The use of nanofluids for industrial applications depends on its stability during transport and use. In this work, we demonstrate that graphene oxide (GO)-based aqueous nanofluids can remaining stable for as many as 90 days. The structural and morphological analyses showed that the GO samples have an average thickness of two graphitic layers with interlayer spacing of 1 nm. The long-term colloidal stability of the nanofluids was monitored for 90 days using three different techniques: UV-vis, zeta potential (ζ) and DLS, which confirmed this stability. The observed ζ value (average of −64.8 ± 1.81 mV) at 200 ppm of GO is the highest negative value reported at pH = 4. The particle size distribution after 90 days of storage presented a major population with diameter of (530 ± 40) nm that represented 98% of the scattered light intensity.