Fundamental understanding of oxygen content in activated carbon on acetone adsorption desorption

Abstract

To explore the effect of O-containing surface functional groups on volatile organic compounds (VOC) adsorption, three kinds of activated carbons named as PC, PH and ZC, after K2CO3, KOH and ZnCl2 activation respectively, were prepared from tobacco stem. Under room temperature (298 K), the saturated adsorption capacities towards acetone of PC, PH and ZC agree well with the resultants of specific surface area. Noteworthy that the normalized adsorption capacity (adsorption value per area) of these activated carbons display a completely different trend, but positively correlated with the O content. Moreover, acetone desorption processes on these materials were also investigated, and the activation energy of desorption were calculated with the order of PC > PH > ZC. Through density functional theory calculation, we determine the nature difference of these activated carbons with varying O content that O-containing surface groups could obviously strengthen the interaction between acetone and carbon surface via the formed hydrogen bond or van der Waals force, and hence significantly improve the adsorption strength to affect the acetone adsorption and desorption process. This study advances the mechanism of O content in the form of surface functional groups during VOC adsorption/desorption process on activated carbons.