Performance of electrospun nanofibrous membranes for trapping of BTX aromatic hydrocarbons and heavy metal ions: Mechanisms, isotherms and kinetics

Abstract

Fly ash (FA) was considered as an adsorbent for adsorbing some harmful substances because of its unique characteristics such as high specific surface area, porosity, functional groups, unburned carbon content in the ash, etc. In this study, FA powder with polyacrylonitrile (PAN) matrix was electrospun into a multi-functional nanofibrous membrane for trapping of BTX aromatic hydrocarbons (benzene, toluene, and xylene) and heavy metal ions. These obtained FA/PAN composites possessed the satisfactory adsorption capacity for BTX aromatic hydrocarbons and heavy metal ions including Co(II), Pb(II) and Cr(VI). The performance of electrospun PAN-based FA nanofibrous membranes for trapping of BTX compounds and heavy metal ions was investigated with emphasis on the mechanisms, isotherms and kinetics. The impact of specific surface area, pore structure, porosity and functional groups on the adsorption behavior as well as adsorbate-adsorbent physicochemical interactions (e.g., electrostatic attraction, nonpolar attraction) were discussed. The results showed that all the tested materials had the strongest adsorption capacity for trapping of xylene, followed by toluene and benzene, and for trapping of heavy metal ions followed the order: Pb(II) > Co(II) > Cr(VI). The most exciting result is that although the trapping of BTX aromatic hydrocarbons by FA/PAN nanofibrous membrane was slightly lower than that by activated carbon (AC) powder, it was about 1.48 and 5.04 times higher than that by AC powder for trapping of Co(II) and Pb(II), respectively. In addition, the initial adsorption rate of FA/PAN membrane and FA powder for heavy metal ions was significantly faster than that of AC powder.