Role of nanomaterials and surfactants for the preparation of graphene nanofluid: A review Kevin Alexander, Sameer Sheshrao Gajghate ⇑ , Anil Shankar Katarkar, Abhik Majumder, Swapan Bhaumik Department of Mechanical Engineering, National Institute of Technology Agartala, Jirania, Tripura 799046, India article info Article history: Received 30 September 2020 Received in revised form 1 November 2020 Accepted 10 November 2020 Available online xxxx Keywords: Graphene Graphene nanofluid Graphene nanoplatelets Graphene oxide Surfactants abstract The exceptional Thermo-physical properties of various graphene nanomaterials need an aqueous or organic form for dispersion to prepare the graphene nanofluids. And, to decide which graphene nanoma- terials and surfactants can be utilized for a particular field of application, hence, dispersion plays an important role in mixing the different graphene nanomaterials and surfactants, which gives the proper concentration and stability of graphene nanofluids. This study presents a summary of the classification of different graphene nanomaterials based on carbon–oxygen structure, the number of layers, composi- tion, synthesis methods, and thermal properties, etc. And, also the classification of surfactants has been carried out on the basis of ionic and non-ionic nature for the perfect dispersion and stability of the gra- phene nanofluid. Hence, from the literature study, it was observed that additional experimentation and research are needed to determine the optimum concentration of various surfactants in nanofluid and its effect on stability, thermal-physical properties. Also, needed More theoretical model preparation to jus- tify the results obtained during experimentation to explain how exactly the parameters affect the prop- erties of the fluid. Ó 2021 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Conference on Materials, Processing & Characterization. 1. Introduction Nanofluids are colloidal suspensions of nanomaterial in base fluid, they consist of two phases one being the solid phase (nano- materials) and the liquid phase (base fluid). Nanofluids have the advantage of offering superior parameters or properties compared with base fluid. Nanofluids have shown to enhance thermal prop- erties such as thermal conductivity, heat transfer coefficient, vis- cosity when comparing to its base fluid. Over the years many metallic and non-metallic based nanofluid have been prepared and studied for its thermal behavior. Based on the research done so far it can be said that a nanofluid properties is as good as the property of its nanomaterial and base fluid used, that is if a nano- material of superior thermal property is dispersed in base fluid like water, oil it can enhance the thermal property of the base fluid tremendously. Thermal conductivity of carbon-based materials has shown to have superior thermal and electrical properties, among them graphene has the highest thermal conductivity of around 3000 W/mK. Graphene was discovered by Novoselov et al. [1], it has excellent chemical, mechanical and physical fea- tures [2,3]. Basically, there are two methods to prepare nanofluids, two step method and one step method as shown in Fig. 1 and Fig. 2. In two step method, first the dry powdered form is nanomaterial is produced by either physical or chemical methods then it is dis- persed into the base fluid with the help of techniques such as ultra- sonic agitation, high-shear mixing, ball milling, magnetic force agitation. This method is commonly used by many researchers for preparing nanofluid due to this method being the most eco- nomical way to prepare nanofluid. But due to the difficulty of preparing stable nanofluid, advanced methods are developed such as one step method. In one step methods the nanomaterial synthe- sis and dispersion in the fluid is done simultaneously thus elimi- nating steps such as drying, storage, transportation such as in two step method. Stability achieved by utilizing this method is high, but it cannot be used to prepare nanofluid in large scale and cost of preparing nanofluid becomes high. The most important demerit in one step method is that residual reactants are present in the nanofluid due to incomplete reaction, this makes the nanofluid impure. Even after nanofluids are prepared, the major concern is its https://doi.org/10.1016/j.matpr.2020.11.231 2214-7853/Ó 2021 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Conference on Materials, Processing & Characterization. ⇑ Corresponding author. E-mail address: mtech_sameer@yahoo.in (S. Sheshrao Gajghate). Materials Today: Proceedings xxx (xxxx) xxx Contents lists available at ScienceDirect Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr Please cite this article as: K. Alexander, S. Sheshrao Gajghate, A. Shankar Katarkar et al., Role of nanomaterials and surfactants for the preparation of gra- phene nanofluid: A review, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2020.11.231