Chemically activated carbon nanofibers for adsorptive removal of bisphenol-A: Batch adsorption and breakthrough curve study

Activated carbon nanofibers (ACNFs) with small diameter can significantly increase the accessibility of intra pores and accelerate adsorption of molecules from water. In this study, ACNFs were made by blending K2CO3 or ZnCl2 as the activating agent into the polyacrylonitrile (PAN) in dimethylformamide solution for electrospinning prior to pyrolysis. Bisphenol-A (BPA), an endocrine disruption pollutant, is widely applied in the production of polycarbonate plastics and epoxy resins. Accordingly, BPA is often used as a model contaminant commonly removed via adsorption. Batch adsorption studies were used to evaluate the kinetics and adsorption capacity of the ACNFs. Redlich–Peterson (R–P) and Langmuir models were found to fit the isotherm of BPA adsorption better than Freundlich model, showing the homogeneous nature of the PAN originated ACNFs. The adsorption kinetics was better described by the pseudo second-order model than that by the pseudo first-order model. The fitting by intraparticle diffusion model indicates the adsorption of BPA onto ACNFs is mainly controlled by pore diffusion. High pH value and ionic strength reduced BPA adsorption from aqueous solution. The breakthrough curves studied in two different fixed bed systems (cross flow bed system and packed flow bed system) confirmed the scalability of BPA removal by ACNFs in dynamic adsorption processes. The modified dose–response model predicted well the fixed-bed outlet concentration profiles.