Preparation of Forcespun Amidoximated Polyacrylonitrile-graphene Oxide Nanofibers and Evaluation of Their Uranium Uptake from Aqueous Media

In this study, a handmade forcespinning device was developed to prepare polyacrylonitrile (PAN) and polyacrylonitrile-graphene oxide (PAN-GO) nanofibers. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to investigate the morphology and characterization of the nanofibers. Modified PANGO((0.2%)) nanofibers were obtained by reducing nitrile groups to amidoxime and then applied to uptake uranium ions from aqueous media. The maximum adsorption obtained for the adsorbent was 345.084 mg g(-1), which was obtained under optimal conditions of pH=5, contact time of 90 minutes and initial concentration of 25 mg L-1. Also, the adsorption data were evaluated using Langmuir, Freundlich, Dubin and S-shaped isotherms. The results introduced the S-shaped isotherm model with a regression coefficient (R-2) of 0.999 as a suitable model. In addition, kinetic studies represented that uranium adsorption for less than 45 min fits well with the pseudo-second-order model (R-2 =0.979). At times longer than 45 min, the nanofibers follow the S-shaped kinetics (R-2=0.999). Eventually, negative ;G (Gibbs free energy change) represents spontaneous adsorption of uranium ions by PAN-GO((0.2%)). The selectivity of PAN-GO nanofibers for the adsorption of competing ions was in accordance with the order Fe(II) < Ni(II) < CO(II) < U(VI) < V(V).

Automated summary

A handmade forcespinning device was developed for preparing PAN and PAN-GO nanofibers, which showed a maximum adsorption capacity of 345.084 mg/g for uranium ions. The nanofibers followed S-shaped kinetics for adsorption over extended periods, with a regression coefficient of 0.999. Selectivity studies indicated that PAN-GO nanofibers had a preference for adsorbing uranium ions over Fe(II), Ni(II), Co(II), and V(V).