The influence of treatment temperature on the acidity of MWCNT oxidized by HNO3 or a mixture of HNO3/H2SO4

• Published in: Applied surface science 2011-06, Vol.257 (17), p.7746-7751
• Main Author: SALEH, Tawfik A
• Format: Article
• Language: English
• Subjects: Clusters, nanoparticles, and nanocrystalline materials; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Fourier transforms; Functional groups; Infrared absorption; Infrared and Raman spectra; Infrared and raman spectra and scattering; Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals; Nitric acid; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Oxidation; Oxygen content; Physics; Single-crystal and powder diffraction; Strategy; Structure of solids and liquids; crystallography; Surface chemistry; X-ray diffraction and scattering
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2011.04.020

The nature of multi-walled carbon nanotubes (MWCNTs) varies with the change in oxidation conditions. In this work, the effect of treatment temperatures on the acidity of MWCNTs was studied. Oxidation was performed by refluxing the MWCNTs in nitric acid or mixtures of sulfuric acid and nitric acid at different temperatures. After oxidative treatment, a quantitative characterization of o-MWCNTs has been performed using acid-base titrations which show that the number of surface acidic functional groups increased by increasing the treatment temperatures. Energy dispersive X-ray (EDX) measurements show that the oxygen content increased with increasing treatment temperatures. Fourier transform infrared absorption spectroscopy (FTIR) was used for qualitative characterization. It has been demonstrated that the acidity is a function of the type of oxidizing agent used and the treatment temperatures. Due to the importance in attachment strategies and functionalization, this study adds to the global discussion of the possibility of controlling the MWCNTs' surface chemistry which plays a crucial role in determining its reactivity.