Characterizations of MWCNTs Nanofluids on the Effect of Surface Oxidative Treatments

Abstract

In this study, multi-walled carbon nanotubes (MWCNTs) were chemically modified using three acid treatment methods to introduce the surface oxygen functional group (SOFG). The presence of SOFG on the MWCNTs has been characterized by Fourier Transform Infrared (FTIR) spectroscopy. Morphology, structural and thermal properties were performed using Field Emission Scanning Electron Microscopy (FESEM), Raman spectroscopy, and Thermogravimetric analysis (TGA), respectively. The result shows that the modification with acid treatment significantly affects the degree of defects and surface group functionality of surface oxidized MWCNTs from method B. The preparation of nanofluids using MWCNTs produced from method B (MWCNT-MB) was prepared using two different parameters: with and without polyvinylpyrrolidone (PVP) as surfactant. The experiment was conducted by setting variable carbon particle concentration from 0.1 wt.% to 1.0 wt.%, and the amount of PVP is 10% of carbon particles at different temperatures (6 °C, 25 °C, 40 °C). Based on visual observation, the dispersion of carbon particles was enhanced by the presence of PVP as the stabilizing agent. The thermal conductivity performance of nanofluids revealed that the surface oxidized MWCNTs with PVP show enhanced thermal conductivity compared to the nanofluid containing MWCNTs without PVP. The improvement contributes to this in terms of stability and homogenization of nanoparticles. Hence the improved distribution of MWCNTs in water-based media improves thermal conductivity. These promising properties of MWCNTs in water-based fluids would enable the nanofluids to be used in heat transfer fluid and cooling applications.

Durable superhydrophobic/superoleophilic melamine foam based on biomass-derived porous carbon and multi-walled carbon nanotube for oil/water separation

“…6 b). Three contact angle measurements were carried out in various places, and the findings were provided according to their mean value 80 . As shown in Fig.…”

Optimizing MWCNT-Based Nanofluids for Photovoltaic/Thermal Cooling through Preparation Parameters

“…This happens because the amphiphilic molecules that make up the surfactant line up on the air side (hydrophobic) and the water side (hydrophilic) of the liquid’s surface. As a result, the surface tension decreases. − In the experiments, three types of surfactants (Table ) were used due to their availability in the local markets at a reasonable cost and the fact that they are some of the most commonly used surfactants in research involving nanofluids. Table presents information regarding the type of surfactants, their chemical structure, TCs, and other relevant specifications supplied by the various manufacturers.…”

Effect of Different Preparation Parameters on the Stability and Thermal Conductivity of MWCNT-Based Nanofluid Used for Photovoltaic/Thermal Cooling

“…Three types of surfactants (Table 2) were also used in the experiments. These surfactants were used in research conducted by Mohd Saidi et al in 2022 [51]. These surfactants were selected for their availability in local markets at a reasonable cost and for being one of the most commonly used types in research works that dealt with nanofluids.…”

“…In the second set, 0.5% (mass fraction) of the tested surfactants (Table 2) was added to the prepared emulsions, adopted from the results of Mohd Saidi et al in 2022 [51]. The effect of the added surfactant was very limited on the resulting thermal conductivity, as it did not increase in a noticeable way, as Figure 4 indicated.…”