Multiwall carbon nanotubes purification and oxidation by nitric acid studied by the FTIR and electron spectroscopy methods

A process of wet chemical purification, oxidation and functionalization of multiwall carbon nanotubes (MWCNTs) is investigated to determine the structural and chemical changes in atomic bonding caused by oxidation in an aqueous solution of concentrated (68%) HNO3 at 120 °C. The original and oxidized multiwall carbon nanotubes (ox-MWCNTs) are studied using TEM, SEM, elemental analysis, mass spectrometry, EDX, FTIR, Raman and electron spectroscopy methods. The proposed wet chemical purification and modification of “as-prepared” MWCNTs, contaminated with amorphous carbon, catalyst supports and metallic catalysts removes effectively all impurities (traces of Al, Fe and amorphous carbon) resulting from the catalytic reaction applied for synthesizing the “as-prepared” MWCNTs. The proposed wet chemical purification of MWCNTs changes their hydrophobic nature to hydrophilic.