Preparation of polyethyleneimine-modified porous polyacrylonitrile electrospun nanofibers for efficient removal of methyl orange

In this study, polyethyleneimine (PEI)-modified porous polyacrylonitrile electrospun (PPAN-PEI) nanofibers were successfully prepared and utilized as absorbent for removal of methyl orange from water. Porous polyacrylonitrile (PPAN) nanofibers were firstly generated by electrospinning method using polyvinylpyrrolidone as the pore-making agent. Then PPAN-PEI nanofibers were prepared by combining hydrolysis and amidoximation modification of the PPAN nanofibers. The obtained nanofibers are systematically characterized, and several basic parameters influencing the adsorption-based removal efficiency are researched, including pH of solution, temperature and contact time. The results show that the PPAN-PEI nanofibers with an average diameter of 480 nm and high specific surface area (43.520 m2 g−1) exhibited the high adsorption capacity (726.45 mg g−1 at pH 6) toward methylene orange (MO), and the adsorption isotherms and kinetic data are well fitted by Langmuir and pseudo-second-order kinetic models. Moreover, the adsorption efficiency toward MO by PPAN-PEI nanofibers still retained over 86.7% of its initial adsorption capacity after five adsorption/desorption cycles, which signify that the adsorbents are stable and recyclable. These superiorities make PPAN-PEI nanofibers a promising adsorbent for the removal of dyes.