Preparation and Cr (VI) adsorption of functionalized polyimide fibers

Abstract

In order to overcome the shortcomings of nanofiber membranes such as low mechanical properties and poor acid resistance, amino-rich functionalized polyimide (PI)-polyethyleneimine (PEI) fibers were successfully prepared in the study. The structure and morphology in each functionalization step were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), static contact angle, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS) measurements. The adsorption kinetics analysis showed that the adsorption process followed a pseudo-second-order model, and the adsorption isotherm could be described better by the Langmuir model indicating the adsorption process was mainly chemical and homogeneous monolayer adsorption. Furthermore, the maximum adsorption capacity based on the Langmuir model was about 50 mg g À1 , and the calculated thermodynamic parameters demonstrated an endothermic process. Meantime, the PEI-grafted PI fibers also exhibited good regeneration performance and stable tensile strength during recycling tests process. In the first 3 adsorption-desorption cycles, the removal efficiency and tensile strength of PI-PEI fibers could be maintained up to 60.44% and 89.29% of the initial adsorption, respectively. This work achieved the function of removing Cr (VI) by combining the excellent high temperature resistance, acid resistance, and mechanical properties of PI fibers.

Grafting Polyethyleneimine–Poly(ethylene glycol) Gel onto a Heat-Resistant Polyimide Nanofiber Separator for Improving Lithium-Ion Transporting Ability in Lithium-Ion Batteries

“…To further verify the graft of PEI as well as PEG to the polyimide nanofibers, the XPS spectra of the polyimide mats were examined, and the results are shown in Figure . In addition, the different peak locations and the FWHM parameters of N 1s and O 1s are shown in Table S1. − Compared to the N 1s and O 1s energy spectra of PI, the peaks of amide, amine, and ammonium obviously increased in the N 1s energy spectrum of PI-PEI (Figure a) and so did the peak of amide in the O 1s energy spectrum of PI-PEI, demonstrating the successful grafting of PEI onto the PI nanofibers. Compared to the O 1s energy spectrum of PI and PI-PEI (Figure b), the peak of the aliphatic ether bond (blue one) in the O 1s energy spectrum of PI-mod significantly increased when PEG was further introduced, demonstrating that PEG was also successfully grafted onto the PI-PEI nanofibers.…”

Preparation of a Chitosan/Coal Gasification Slag Composite Membrane and Its Adsorption and Removal of Cr (VI) and RhB in Water

“…Figure 9 d shows the high-resolution Cr 2p -XPS map. The XPS peaks at 579.98 eV and 583.94 eV binding energy correspond to Cr (VI) in Cr 2 O 7 2− and CrO 4 2− [ 25 ]. However, we found that the binding energy positions of peaks were significantly larger than those of the standard binding energy, indicating that the electrons adsorbed by Cr 2 O 7 2− may have been transferred to F-0.…”