Effects of pore structures and multiple components in flue gas on the adsorption behaviors of dioxins by activated carbon

Abstract

Pore structures of activated carbons (AC) were vital to the removal of dioxins. However, to determine the key pore parameter is a still challenging task to the design of adsorbents for dioxins. The effects of multi-pollutants in the complicated flue gas on the elimination of dioxins are also unknown. Herein, the effects of pore structure on the dioxins adsorption were evaluated through ACs modified by CO2 with dibenzofuran (DBF) as the model molecular. The modified ACs possessed a higher DBF adsorption capacities with a maximal adsorption capacity of 709.1 mg/g. The positive correlations between pore parameters and adsorption capacity followed an increasing order of Vmicro < VT < SBET < Vmeso, indicating that pore size distribution ranging from 2 to 6 nm was beneficial to DBF adsorption, which was confirmed by grand canonical monte carlo (GCMC). The competitive adsorptions between DBF and other pollutants (SO2, NOx, H2O) inhibited the DBF adsorption process slightly, and the results of competitive adsorption experiments manifested that DBF was easier to be adsorbed on ACs than other pollutants owing to the higher affinity and adsorption energy, which was also verified by the density functional theory (DFT). This study provided sound theoretical guidance for the design of ACs adsorbents in the multi-pollutant cooperative control technology with activated carbons.