effect of acid treatment of carbon nanotubes on their adsorption capacities of benzene and toluene

toluene and benzene were eliminated using multi-walled carbon nanotubes (mwcnts). in order to investigate influence of acid treatment on the mwcnts adsorption capacities, the mwcnts were functionalized by nitric acid (10 m) under reflux conditions for 2 h. fourier transform infrared (ftir) and raman spectroscopy were employed to confirm the formation of functional groups on the nanotubes surface. specific surface areas of the nanotubes were also measured using the brunauer–emmett–teller (bet) method. adsorption capacities of the functionalized and unfunctionalized mwcnts were obtained and then compared with each other. ftir and raman spectra proved the formation of functional groups on the mwcnts surface as a result of this acid treatment. adsorption capacities measurements revealed that the functionalized mwcnts have large adsorption capacities of toluene and benzene as compared with the unfunctionalized mwcnts. this enhancement of adsorption capacities was ascribed to an increase in the specific surface area of the nanotubes due to this acid treatment.