Gas phase interactions of super activated carbon nanoparticles with benzene, o-xylene, and water vapor

Engineered nanomaterials (ENMs) might have unique and different properties such as surface area, conductivity, and reactivity as compared to the larger particles of the same material. Engineered nanomaterials released into the environment may undergo atmospheric transformations by adsorbing hazardous air pollutants (HAPs) such as benzene and o-xylene. A bench-scale adsorption column experiments were conducted to investigate the adsorption competition of binary and ternary gas mixtures of benzene, o-xylene and water vapor on super activated carbon nanoparticles (SACNPs). Gas phase mixtures of unimolar and multimolar adsorption experiments were carried out. Results showed that in binary adsorption, o-xylene displaced benzene from the pore sites, and higher concentrations of o-xylene caused more competition with benzene for the SACNPs pore sites. However, in ternary adsorption the water vapor seems to be responsible for the decrease of the adsorption capacity of SACNPs for benzene. The adsorption kinetics for benzene and o-xylene on SACNPs showed best agreement with pseudo second-order model. The adsorption rate of benzene on SACNPs was faster when other adsorbates were present in the gas mixture. On the other hand, o-xylene adsorption kinetic remained constant in binary and ternary adsorption experiments. To the best of my knowledge, this is the first study that quantifies the interactions of SACNPs with toxic vapors which suggests a potential impact on human health for indoor air quality applications