Preparation and characterization of carbon nanofluids by using a revised water-assisted synthesis method

A revised water-assisted synthesis system (RWAS) was used to fabricate carbon/water nanofluids (CWNFs). The CWNFs were manufactured by heating graphite rods at different temperatures (700, 800, 900, and 1000°C). Aspects of the CWNFs and suspended nanocarbon, such as the morphology, structure, optical characteristics, and production rate, were fully characterized. Furthermore, the suspension performance of the CWNFs was controlled by adding a dispersant (water-soluble chitosan) at different concentrations. Finally, the CWNFs were determined to assess the influence of both the heating temperature of the graphite rod module (process temperature) and the dispersant concentration on the fundamental characteristics of the CWNFs. The results showed that the nanocarbon was a mixture of nanocrystalline graphite and amorphous carbon. Heating the graphite rod module at higher process temperatures resulted in a higher production rate and a greater nanocarbon particle size. Furthermore, adding dispersant could improve the suspension performance; increase the viscosity, density, and specific heat; and reduce the thermal conductivity of the CWNFs. The optimal combination of the process temperature range and dispersant concentration was 800 to 900°C and 0.2 wt.%, respectively, based on the production rate, suspension performance, and other fundamental properties of the CWNFs.