Adsorption and Desorption of Chlorinated Compounds from Pristine and Thermally Treated Multiwalled Carbon Nanotubes

We report on the adsorption and desorption behavior of chlorinated compounds on as-produced as well as heat-treated multiwalled carbon nanotubes (MWCNTs). Adsorption and desorption studies of trichloroethylene (TCE), 1,1,1-trichloroethane (1,1,1-TCA), and 1,3,5-trichlorobenzene (1,3,5-TCB), three chlorinated compounds with different molecular structures, on M4VCNT bundles were performed. Adsorption measurements indicated that adsorption capacities of these chlorinated compounds to MWCNTs are greatly affected by the molecular structures and follow an order of 1,1,1-TCA < TCE < 1,3,5-TCB. A pronounced desorption hysteresis was observed for all the adsorbate compounds that were experimented on pristine MWCNTs. Similar adsorption and desorption investigations on thermally treated MWCNTs showed an increased sorption capacity of these compounds (39-97%). However, in the case of the heat-treated MWCNTs, reduced desorption hysteresis was noticed, possibly due to the removal of disorderly amorphous carbon and certain surface modification. These results indicate that simple heat treatment of MWCNTs could increase the adsorption capacity of these chlorinated compounds and drastically change the adsorption characteristics of MWCNTs.