Microwave-assisted synthesis of a novel modified polyacrylonitrile fiber and its adsorption performance for Cr(Ⅵ)

Polyacrylonitrile-2-aminopyridine (PAN-TAP) is a novel chelating fiber rapidly prepared by a microwave-assisted synthesis method. By controlling the synthesis temperature, time, and microwave power, the optimal synthesis conditions for the chelating fiber were determined, and the preparation time only takes 30 min. This material was characterized by elemental analysis, Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Meanwhile, the adsorption characteristics and mechanism of PAN-TAP for Cr(Ⅵ) were evaluated. The adsorption process conforms to the Langmuir isothermal adsorption model and the pseudo-second-order kinetic model, indicating that the adsorption mechanism is a chemisorption of monolayer adsorption. Cr(Ⅵ) is reduced to Cr(Ⅲ) by the amino groups on the fiber and then adsorbed. The maximum theoretical adsorption capacity is 287.1 mg/g (at 298 K), and the adsorption equilibrium can be reached within 1 h. The results of the thermodynamic parameters suggest a spontaneous and endothermic process. Overall, PAN-TAP is a cost-effective and rapid adsorbent, which has broad application prospects for the removal of Cr(Ⅵ) in water.