Devising Carbon Nanotube, Green Tea, and Polyaniline Based Nanocomposite plus Investigating Its Rheological together with Bactericidal Efficacies

Abstract

Subsequently, engines are designed to operate at low viscosity engine oils. Low viscosity oils take less power from engines, bring down the internal drag, cut the fuel consumption, and ultimately improve the engine's efficiency. Considering this focus, an approach has been made to formulate a multiwalled carbon nanotube based green tea and polyaniline nanocomposite, that is, GT/MWCNT/PANI, and incorporate it in engine oil (base fluid). The objective was to reduce the viscosity of engine oil by examining the effects of the constant shear rate and varying shear rates on the viscosity of Castrol class 15W-40 engine oil. The investigation was performed at a constant temperature of 25 °C for a fixed volume fraction of 0.1% GT/MWCNT/PANI in engine oil on the experimental setup rheometer from Anton Paar Series. Primordial findings revealed that, at a constant shear rate of 100 s^-1, engine oil viscosity was lowered from 0.221000 to 0.001402 Pa·s, that is, 99% reduction in viscosity of the engine oil, after incorporating the GT/MWCNT/PANI nanocomposite. Furthermore, a new correlation has been proposed considering the experimental and theoretical models with an average percentage error of 0.040%. Also, at varying shear rates, up to 90 s^-1, the shear viscosity of nanofluid decreases significantly, leading to shear-thinning behavior of the nanofluid, while at a shear rate of >90 s^-1, it shows Newtonian behavior. Besides, the ternary nanocomposite with 0.2 wt % GT/MWCNT/PANI also showed significant bactericidal effects with the zones of inhibition of 19, 18, and 15 mm against Gram-negative (Pseudomonas aeruginosa, Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria, respectively, as measured using the well diffusion method.

Figure 1

(a–c) SEM micrographs of pure green tea (GT) at 10, 5, and 10 μm and (d–f) SEM micrographs of GT/MWCNT/PANI nanocomposite at 10 μm.

Figure 2

FTIR graph of GT/MWCNT/PANI.

Figure 3

TGA of green tea (GT) and GT/MWCNT/PANI composite.

Figure 4

Viscosity variation of GT/MWCNT/PANI in 15W-40 engine oil (base fluid) with time at a constant shear rate of 100 s^–1.

Figure 5

Comparison between the experimental and theoretical values of GT/MWCNT/PANI viscosities at a constant shear rate.

Figure 6

Effect of shear rate on viscosity of GT/MWCNT/PANI nanocomposite dispersed in 15W-40 engine oil.

Figure 7

Well diffusion assay of (a) S. aureus, (b) E. coli, and (c) P. aeruginosa showing zones of inhibition in the presence of samples (01, 02, and 03) (GT, 0.1 wt % GT/MWCNT/PANI, and 0.2 wt % GT/MWCNT/PANI).

Figure 8

3D bar charts representing the antibacterial potential of GT and 0.1% and 0.2% GT/MWCNT/PANI against bacterial isolates belonging to genera Gram-positive (S. aureus) and Gram-negative (P. aeruginosa and E. coli) as measured by well diffusion test.