Recovery of Ag(I) from aqueous solution by hyperbranched polyethyleneimine grafted polyacrylonitrile/graphene oxide electrospun nanocomposite fiber membrane for catalytic reduction of toxic P-nitrophenol

Abstract

A novel hyperbranched polyethyleneimine grafted polyacrylonitrile/graphene oxide (HPEI-PAN/GO) electrospun nanocomposite fiber membrane was successfully fabricated by electrospinning technology and chemical grafting reaction. The HPEI-PAN/GO electrospun nanocomposite fiber membrane was used for recovery of Ag(I) from aqueous solution. The obtained electrospun nanocomposite fiber membrane fabricated by GO and PAN through self-fusion could avoid the shedding of GO and increase the dispersion of GO in PAN. HPEI containing plenty of primary and secondary amine groups, grafted the PAN/GO electrospun nanocomposite fiber membrane can increase the adsorption capacity for Ag(I) and reduce Ag(I) into element silver during the adsorption process. The maximum adsorption capacity of the HPEI-PAN/GO electrospun nanocomposite fiber membrane was 167.40 mg·g−1 and the removal ratio remained above 90 % after five regeneration cycles. The HPEI-PAN/GO electrospun nanocomposite fiber membrane adsorbed Ag(I) (HPEI-PAN/GO-Ag) was utilized as catalyst for the reduction of toxic p-nitrophenol (4-NP) to 4-aminophenol (4-AP). The HEPI-PAN/GO-Ag could remain the catalytic conversion over 90 % for 4-NP after 10 catalytic cycles, manifesting that the HPEI-PAN/GO-Ag had significant catalytic activity and outstanding stability. This work provides a novel strategy for recovery and reuse of precious metal ions from wastewater.