Isolation and identification of low molecular weight carboxylated carbons derived from the nitric acid treatment of single-walled carbon nanotubes

Single-walled carbon nanotubes (SWCNTs) were purified by treatment with concentrated nitric acid and then subjected to Soxhlet extraction with tetrahydrofuran (THF). The THF extract of low molecular weight carboxylated carbons was derivatized with (trimethylsilyl)diazomethane and the resulting methylated material was separated with column chromatography and thin layer chromatography and several fractions were identified by GC–MS and 1H NMR. The fractions were shown to include small benzopolycarboxylic acids and organic nitro compounds.