Towards understanding reactive adsorption of small molecule toxic gases on carbonaceous materials

Abstract

Reactive adsorption is a separation process based on physical adsorption of molecules, which is followed by their chemical transformations on the surface. This process is especially important for the removal of toxic industrial compounds (TICs) from air. At ambient conditions their adsorption is very weak and such factors as the presence of humidity have to be taken into account. This paper presents our approach leading to the design of efficient TICs adsorbents. In these materials the pores should be small enough to attract adsorbate molecules but sufficiently big to accommodate water or functional groups which participate in surface reactions. In these specific nanoreactors toxic species are either transformed to nontoxic and removed from the system or they are strongly retained on the surface via chemical bonds or as nonvolatile species. Surface chemistry is very important for these transformations. To start designing new separation media the physical properties of molecules and their chemical reactivity should be of paramount importance. After a separation performance test the battery of analytical methods has to be employed to characterize the surface of materials before and after reactive adsorption. The results obtained are then analyzed and the mechanism of adsorption is derived with the indication of surface features, which play a critical role in a particular separation process.