Phenol adsorption on closed carbon nanotubes

► Phenol adsorption on a series of eight closed carbon nanotubes was measured. ► We observe the linear correlation between surface area of tubes calculated from phenol and nitrogen adsorption. ► Phenol can be applied as a probe molecule for comparative analysis of tube surface areas. ► Adsorption process is mainly determined by the value of tube external surface areas and the tubes behave almost independently.