Dibenzo-18-crown-6/Polyacrylonitrile (PAN) nanofibers for metal ions adsorption: adsorption studies for Na+ and K+

Dibenzo-18-crown-6 (DB18C6) as a host compound was doped into polyacrylonitrile (PAN) solution. The composite nanofibers (DB18C6/PAN) were prepared by the electrospinning. The morphology, chemical structure and thermal stability of nanofibers were characterized by field emission scanning electron microscope (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), and thermal gravimetric analysis (TGA), respectively. The composite nanofibers with good morphology were obtained by controlling the weight percent of DB18C6 and electrospinning parameters. The static adsorption behavior of alkali metal ions and alkaline earth metal ions of different proportional DB18C6/PAN nanofibers were studied. DB18C6/PAN nanofibers have adsorptive selectivity about alkali metal ions: K+ > Na+ > > Cs+ > Li+. The 15wt%DB18C6/PAN nanofibers have the highest adsorption capacity. The adsorption kinetics of 15wt%DB18C6/PAN nanofibers for Na+ and K+ were accorded with the first-order equation, and the adsorption rate constants were 9.5 x 10(-3) min(-1) and 1.5 x 10(-2) min(-1), respectively. At 25 degrees C, the isotherm adsorption of the DB18C6/PAN nanofibers for Na+ and K+ was confirmed to the Langmuir adsorption isotherm, and the maximum adsorption quantities of 15wt%DB18C6/PAN nanofibers were 11.9 mg g(-1) and 24.8 mg g(-1), respectively.

Automated summary

In this study, DB18C6/PAN composite nanofibers were prepared by electrospinning, with good morphology achieved by controlling DB18C6 weight percent and electrospinning parameters. The nanofibers exhibited adsorptive selectivity towards alkali metal ions, with the 15wt%DB18C6/PAN nanofibers showing the highest adsorption capacity. Adsorption kinetics of the 15wt%DB18C6/PAN nanofibers for Na+ and K+ followed the first-order equation, and adsorption isotherms were confirmed to Langmuir adsorption isotherm model.