Adsorption behaviors of VOCs under coal-combustion flue gas environment using activated carbon injection coupled with bag filtering system

Adsorbent injection is a simple and efficient technique for flue gas purification. Performances of volatile organic compounds (VOCs) removal in coal-combustion flue gas environment were investigated by activated carbon (AC) injection coupled with bag filtering (ACI + BF). Results showed that the removal efficiency of toluene and p-xylene was not only related to the micropore volume of AC but also to the pore size distribution and mesopore volume. Waste AC could be reused without desorption, the removal efficiency of mixed ACs was close to the fresh AC when the proportion of waste AC was 25%. Under complex coal-combustion flue gas environment, the adsorption efficiency of p-xylene was decreased by 19.0%. The fly ash in flowing state had less influence on the adsorption of VOCs on AC. On the adsorption layer of filter bag, fly ash decreased the AC concentration and blocked some important mass transfer channels of VOCs, restricting the diffusion of VOCs to the AC outer surface and decreasing utilization efficiency of adsorption sites. Although the concentration of SO2 was high, the inhibitory effect on VOCs adsorption was not significant. As the water vapor and SO2 coexisted, the H2SO4 was formed and blocked some micropores. Then the VOCs diffusion in the AC inner pores was influenced and some micropores could not adsorb VOCs. The removal of VOCs in both pipeline and adsorption layer was influenced by SO2 and water vapor. [Display omitted] •Faster adsorption kinetic of AC leads to higher VOCs removal efficiency on ACI + BF system.•Waste AC without desorption can be reused with the blending mass ratio of 25%.•Inhibition of fly ash on VOCs adsorption is mainly in the adsorption layer of filter bag.•H2SO4 in AC inner pore decreases micropores utilization efficiency and adsorption rate.