Combined Effect of Surface Treatment and Surfactant on CNT Nanofluids Preparation

Abstract

-CNT nanofluids deliver better rate of heat transfer due to the presence of CNTs which are having high thermal conductivity. Since CNTs are hydrophobic in nature , they entangle themselves and form agglomerates specially in polar solvents. The agglomerates settle down with time and cause reduction in thermo-physical properties and hence lose their potential to deliver better rate of heat transfer. This characteristic of CNT nanofluids requires an efficient preparation method which can provide uniform dispersion of CNTs for a longer duration. This study has been focused on preparation of long term stable CNT nanofluids having effective dispersion of CNTs by the removal of agglomerates which were formed during preparation. To disperse CNTs in water two type of surfactants i.e. sodium dodecylbenzene sulfonate (SDBS) and gum arabic (GA) were used followed by ultrasonication. Based on results, it was analyzed that there is an optimum concentration of both the surfactants which provide maximum dispersion of pristine (p-CNTS) and functionalized (f-CNTS) at particular ultrasonication time. The maximum dispersion concentration of f-CNTs was found to be more than p-CNTs under same conditions. The dispersion of CNTs was more in case when GA was used as surfactant in comparison to SDBS irrespective of ultrasonication time while the thermal conductivity was more for SDBS based CNT nanofluids instead of GA irrespective of type of CNTs. The thermal conductivity of CNT nanofluids was sufficiently high that can be utilized in industries where there is requirement of heat transfer.