Novel ultraporous polyimide-based hollow carbon nanofiber mat: Its polymer-blend electrospinning preparation strategy and efficient dynamic adsorption for ciprofloxacin removal

A novel ultraporous polyimide-based hollow carbon nanofiber mat (CNFM) was facilely fabricated via a polymer-blend electrospinning strategy, which consisted of a simple single-needle electrospinning of two immiscible polymer solutions (polyamide acid/polymethyl methacrylate) (PAA/PMMA) and the subsequent thermal treatment, without involvement of tedious and cost-consuming activation steps. The obtained PP-CNFM-1–1 (PAA:PMMA = 1:1, mass ratio) exhibited well-developed hollow cores along the fiber length, and possesses ultrahigh Brunauer-Emmett-Teller (BET) specific surface area (SBET) of 2327 m2 g-1 and a large total pore volume of 1.26 cm3 g-1, which were superior to many activated CNFMs. The PP-CNFM-1–1 showed high ciprofloxacin (CIP) adsorption capacity of over 700 mg g-1 due to its ultrahigh SBET and abundant pores of 1–3 nm width fitting CIP molecule. Notably, the hollow core of PP-CNFM-1–1, which is similar to molecular channel, was the reason to the excellent CIP adsorption rate and a very short adsorption equilibrium time (<1h). Adsorption mechanism study implied that the pore filling effect and the hydrophobic interaction played the major roles in the adsorption process. The fixed-bed column adsorption study indicated that the PP-CNFM-1–1 had a great application potential for low concentration CIP removal.