Preparation and Characterization of Polyacrylonitrile/Aluminum Oxide Nanofiber Adsorbent Modified with 2-Amino-3-Methyl-1-Hexanethiol for the Adsorption of Thorium (IV) Ion from Aqueous Solution

Abstract

In this study, a novel polyacrylonitrile/aluminum oxide (PAN/Al−ONPs) nanofiber adsorbent modified with 2-amino-3-methyl-1-hexanethiol (AMH) was synthesized by a combination of hydrothermal and electrospinning and evaluated as an adsorbent for removing thorium (IV) (Th4+) ion from aqueous solution. The PAN/Al−ONPs/AMH was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Brunauer–Emmett–Teller (BET) analysis. Response surface methodology (RSM) was used in the optimization of Th4+ adsorption for parameters such as pH, initial metal ion concentration (Th4+ concentration), and contact time. Design-Expert 7 was used for modeling these three variables. Statistical measures validated the developed model (R2=.9415). In addition, the adsorption kinetics was well defined by the pseudo-second-order equation (R2=.98) whereas the adsorption isotherms were better fit by the Langmuir model (R2=.95). The adsorption capacity of PAN/Al-ONPs/AMH, 472 mg Th4+g−1 composite, led to 98% removal at 25°C. Moreover, thermodynamic parameters were determined which showed the endothermic nature of the reactions. The loaded Th4+ can be easily regenerated with HNO3/HCl. Also, the desorption level of Th4+ by the PAN/Al-ONPs/AMH using .4M HNO3/.2M HCl was more than 92%.