A review on stabilization of carbon nanotube nanofluid

CNT nanoparticles have high tensile strength, excellent thermal transfer properties, and optimal chemical and physical stability. The lack of CNT stable dispersion in most of the fluids limits its industrial exploitation in heat transfer applications. Researchers are constantly making efforts for preparing stable dispersions of CNT. Luckily, the unique pi-electron-rich structures of CNT open a variety of possibilities for modifications in their structure leading to alterations in their chemical and electronic properties. Normally, chemical and physical methods are used for CNT surface properties alterations to make it dispersible in various base fluids. This review provides a comprehensive survey of chemical and physical methods used to prepare stable CNT nanofluid as well as methods used to analyse CNT nanofluid stability. Chemical modifications are either done by covalent or non-covalent methods. Covalent methods utilized by researchers include reaction with acids, bases, organic and inorganic molecules, metals, metal complexes, polymers, etc. In non-covalent method, surfactants, biomolecules and natural products, polymers, IL and DES, polymers, etc. are used. Physical methods discussed herein include techniques like homogenization, crushing, etc. that deagglomerate CNT bundles. The application of extreme forces on CNT leads to distortion in electronic framework of CNT. Therefore, to avoid excess of physical and chemical treatments, a blend of techniques in appropriate ratio is proposed for CNT dispersion. The techniques that are used to analyse the stability of nanofluid such as UV-vis, TEM, SEM, turbiscan, zeta, and DLS are also reviewed. It could be concluded that there is need for development of low-cost and fast method for prediction of the stability of CNT nanofluid.

Automated summary

CNT nanoparticles have high tensile strength, excellent thermal transfer properties, and optimal chemical and physical stability. However, the lack of stable dispersion of CNT in most fluids hinders its industrial exploitation in heat transfer applications. Researchers are utilizing chemical and physical methods to modify the surface properties of CNT for better dispersion, along with various analytical techniques to assess the stability of CNT nanofluid.