Multi-walled carbon nanotube functionalization and the dispersing agents study applied for the glassy carbon electrode modification and voltammetric reduction of nitrofurazone

Multi-walled carbon nanotubes (MWCNTs) have structures characterized by remarkable mechanical and electronic properties. However, their applications can be hindered because of their hydrophobic nature, lack of homogeneity due to impurities, and their variable sizes. Thus, MWCNT was treated by acidic oxidation (H2SO4 3:1 HNO3), seeking out to evaluate the influence of this functionalization on the electrochemical reduction behavior of nitrofurazone applying cyclic voltammetry, the glassy carbon surface having been modified as working electrode. The MWCNT functionalization was characterized by using scanning electron microscopy, infrared and Raman spectroscopies, thermogravimetric analysis, and potentiometric titration. Differences between non-functionalized and functionalized MWCNT were observed, suggesting that carboxylic groups were introduced in the carbon nanotube walls. Moreover, the glassy carbon surface modification was also studied concerning the dispersing agents for functionalized MWCNT. Several solvents of different natures, hydrophilic and lipophilic, were evaluated. The best dispersion associated with electrochemical response of nitrofurazone was obtained with 1,3-dioxolane as dispersing agent, which presented higher affinity with MWCNT than the other solvents. The electrochemical response of the glassy carbon electrode modified with MWCNT was evaluated by nitrofurazone voltammetric behavior with emphasis on the $$ \mathrm{R}-\mathrm{N}{\mathrm{O}}_2/\mathrm{R}-\mathrm{N}{\mathrm{O}}_2^{\cdotp -} $$ couple generation and its kinetic stability.