Methods of dispersion and stabilization of several nanomaterials in water

Carbon nanomaterials are highly hydrophobic that affect their dispersion stability in aqueous solutions and make them limited in practical applications. In order to improve the stability of nanofluid and find the configuration parameters under the conditions of ultrasonic treatment and dispersant, the dispersion stabilization methods and dispersion mechanism were studied in this paper. Multi-walled carbon nanotubes (MWCNTs, 95% MWCNTs), graphene(GNP) and single-walled carbon nanotubes (SWNTs) were selected which with the highest thermal conductivity. Ultrasonic parameters were selected as 285 W and 10 min. The best dispersant for MWCNTs, 95% MWCNTs, GNP and SWNTs was SDBS and optimal ratios (SDBS/ MWCNTs, 95% MWCNTs, GNP, SWNTs) were (0.5-4):1, (1-4):1, (0.25-2):1, (1-4):1 respectively. The dispersion stability of the four nanofluids from good to bad were 95% MWCNTs, MWCNTs, SWNTs and GNP in turn. During the ultrasonic dispersion process, the long carbon tubes were interrupted into shorter carbon tubes, multi-layer GNP was divided into single layers. SDBS added functional groups into the carbon structure of nanomaterials, increasing the number of hydrophilic functional groups and enhancing the dispersion stability.