Modification of carbon nanotubes with sodium p-aminobenzenesulfonate and its effect on Cu2+ adsorption

Multiwalled carbon nanotubes (MWCNTs) were oxidized by concentrate HNO3 and then reacted with SOCl2 to form MWCNT-COCl. Water-soluble sodium p-aminobenzenesulfonate-grafted multiwalled carbon nanotubes (MWCNT-CO-NHC6H5SO3Na) were synthesized by an amidation reaction of sodium p-aminobenzenesulfonate with MWCNT-COCl, which was verified by FT-IR spectroscopy. The content of the sodium p-aminobenzenesulfonate grafted onto the MWCNT surface reached 29.9 mass%. The MWCNT-CO-NHC6H5SO3Na showed a good solubility and dispersion in water, and had an improved adsorptive performance for the removal of low concentrations of Cu2+in water. The adsorption isotherms of the MWCNT-CO-NHC6H5SO3Na for Cu2+ can be well fitted by the Freundlich equation.