Dispersion of Functionalized Multi-Walled Carbon Nanotubes in Aqueous Solution

The stable and homogeneous suspensions of multi-walled carbon nanotubes (MWCNTs) have many practical applications. In this paper, functionalized MWCNTs are obtained by the acid treatment to achieve dispersion of MWCNTs in aqueous solution. Then a method combining the dispersants – sodium dodecylsulfate (SDS) and ultrasonication is used to further disperse functionalized MWCNTs. Some following techniques, including UV–Vis absorbance, surface tension, zeta potential and adsorption isotherm measurements are used to characterize the dispersion of functionalized MWCNTs. Meanwhile, the dispersion mechanism of functionalized MWCNTs is demonstrated using the transmission electron microscopy (TEM). Experimental results show that best SDS concentration for the dispersion of functionalized MWCNTs is 0.65 g/L in aqueous solution. TEM images also shows that the introduction of SDS break up the agglomeration of bundles, hence the thickness of functionalized MWCNTs is decreased greatly. The dispersing mechanism is that the surfactant and hydrophobic effects prevent functionalized MWCNTs from aggregating.