TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The composition further comprises a solvent comprising water, ethanol, propylene carbonate (all preferred), dimethylformamide, and/or pyrrolidinone derivatives, where the carbon nanotubes are suspended in the solvent at 0.1-10 mg/ml, preferably 0.1-0.3 mg/ml. Preferred Method: In the method: the steps of exposing the carbon nanotubes to the solvent and to the acid are performed in a single step comprising mixing the solvent, the acid and carbon nanotubes to form a carbon nanotube-solvent-acid solution; or the step of exposing the carbon nanotubes to the solvent comprises immersing the carbon nanotubes in the solvent to form a carbon nanotube-solvent immersion, and the step of exposing the carbon nanotubes to the acid comprises mixing the carbon nanotube-solvent immersion with the acid to form a carbon nanotube-solvent-acid solution. The method further comprises: heating the carbon nanotube-solvent-acid solution at 50-200 degrees C, and filtering the carbon nanotubes from the carbon-nanotube-solvent-acid solution; or heating the carbon nanotube-solvent immersion and/or the carbon nanotube-solvent-acid solution at 50-200 degrees C, and filtering the carbon nanotubes from the carbon-nanotube-solvent-acid solution. Preferred Components: The functional group is sulfonate functional group. The analogue of N-cyclohexyl-2-pyrrolidone comprises a compound comprising dimethyl-tetrahydro-2-pyrimidinone, N-butyl-pyrrolidinone, benzyl-pyrrolidinone, N-methyl-pyrrolidinone, 3-(2-oxo-1-pyrrolidinyl)propanenitrile, N-ethyl-pyrrolidinone, N-octyl-pyrrolidinone, N-vinyl-pyrrolidinone, dimethyl-imidazolidinone, dimethylacetamide and/or N-dodecyl-pyrrolidone. EXAMPLE - 200 mg Of double-walled carbon nanotubes with a length of 3-30 mu m, 100 ml of N-cyclohexyl-2-pyrrolidone, and 200 ml of 98% sulfuric acid were mixed in a glass beaker. The mixture was then heated at 85 degrees C and stirred with a magnetic stirrer for 24 hours.