The influence of porosity and surface oxygen groups of peat-based activated carbons on benzene adsorption from dry and humid air

Activated carbons (ACs) prepared from peat were used for benzene adsorption (5 ppmv) from dry and humid (relative humidity (RH) 70%) air streams. Benzene uptake by the ACs was lower in the presence of water vapor due to competition between benzene and water molecules for the adsorption sites. Adsorption of benzene from dry and humid air on the ACs with low content of surface oxygen groups was attributed to the presence of narrow micropores (size <0.7 nm). A linear correlation between the amount of adsorbed benzene and micropore volume calculated from CO2 adsorption isotherms was found. The coefficients of determination R2 were 0.87 for benzene adsorption in the absence of water vapor and 0.83 for adsorption at relative humidity 70%. It was shown that the presence of surface groups in the ACs reduces benzene uptake more profoundly in the presence of moisture than in the dry conditions.