Hyperbranched polyethyleneimine functionalized porous polyacrylonitrile/graphene oxide nanofiber membrane for adsorption and reduction of Au(III)

Gold (Au) with excellent properties, is widely used in many fields, resulting in the depletion of Au resources and environment pollution due to a great deal of wastewater containing Au(III) produced in the industrial production process. Hence, it is necessary to remove and recover Au from wastewater. In this work, a novel hyperbranched polyethyleneimine functionalized porous polyacrylonitrile/graphene oxide nanofiber membrane (HP-PAN/GO) for adsorption of Au(III) was fabricated by electrospinning, hot-water soak and grafting methods. The effect of the solution pH, initial concentration and contact time on the adsorption performance of HP-PAN/GO for Au(III) was explored by batch experiments. The adsorption process was investigated by pseudo-first-order kinetic, pseudo-second-order kinetic, intra particle diffusion models, Langmuir and Freundlich isotherms. The results showed that the HP-PAN/GO with abundant amino functional groups and pore structure was successfully fabricated. The adsorption and reduction of HP-PAN/GO for Au(III) were simultaneous, and Au(III) adsorbed HP-PAN/GO was partially reduced to elemental Au with hexagonal flakes and irregular particles, and the maximum adsorption capacity of HP-PAN/GO for Au(III) was 2601.27 mg·g⁻¹. The removal rate of the HP-PAN/GO for Au(III) remained over 83% after five adsorption cycles. Moreover, the HP-PAN/GO had excellent adsorption selectivity in coexisting ion system. The HP-PAN/GO could be a promising candidate for effective removal and recovery of Au(III) in wastewater.