Fabrication of a porous polyacrylonitrile nanofiber adsorbent for removing radioactive Co.

A Co adsorbent was prepared using electrospun porous polyacrylonitrile (PAN) nanofibers, featuring easy recovery for reuse compared with a nanoparticle-based adsorbent. As an efficient ligand for Co, ethylenediaminetetraacetic acid (EDTA) was introduced on the surface of porous PAN nanofibers with the aid of a branched polyethyleneimine (PEI) linker to obtain an adsorbent with carboxylic acid groups. On the adsorbent surface, the carboxylic acid and amine groups from EDTA could adsorb Co via ion exchange and chelation, and amine groups from PEI that remained after EDTA functionalization played a role in coordinating Co. The amine and carboxylic acid groups were simultaneously involved in the adsorption on the surface, making it possible to remove Co over a wide pH range. An investigation of the adsorption isotherms and kinetics of the nanofibrous adsorbent indicated that monolayer chemisorption was achieved with a maximum Co adsorption capacity of 8.32 mg/g. In addition, radioactive Co was efficiently removed by the adsorbent with a removal extent of more than 98%. Considering the easy separation from Co solution and regeneration of the nanofibrous adsorbent and its availability in a wide pH range, the adsorbent has great advantages in practical applications.