Polyimide-based carbon nanofibers: A versatile adsorbent for highly efficient removals of chlorophenols, dyes and antibiotics

In this study, polyimide (PI)-based carbon nanofibers (CNFs) were prepared via electrospining polyamic acid solutions followed by thermal imidization and carbonization. And its versatile adsorption performance for removal of 2,4-dichlorophenol (2,4-DCP), methylene blue (MB) and tetracycline (TC) was evaluated. PI-based CNFs with a high specific surface area of 715.89 m(2) g(-1) exhibited a maximum adsorption of 483.09 mg g(-1), 272.48 mg g(-1) and 146.63 mg g(-1) for 2,4-DCP, MB and TC, respectively. The MB adsorption efficiency was highly pH-dependent with an optimal pH 11, while the CNFs performed well towards TC and 2,4-DCP adsorption in the wide pH range of 4-7 and 3-7. Kinetics and isotherm experiments were fitted well with pseudo-second-order kinetics model and Langmuir model, respectively. Thermodynamic parameters showed that adsorption was spontaneous and endothermic. Moreover, the reusability of PI-based CNFs was evaluated, and the result showed that the removal of 2,4-DCP, TC and MB was kept its high efficiency after 5 consecutive cycles. This study demonstrated that the CNFs should be a powerful adsorbent for the removal of a great number of organic pollutants from aqueous environments.