Green synthesis of porous N-Carbon/Silica nanofibers by solution blow spinning and evaluation of their efficiency in dye adsorption

Porous N-carbon/silica nanofibers (PN-CSN) were successfully made by solution blow spinning (SBS), polymer solutions containing polyvinylpyrrolidone (PVP), tetraethyl orthosilicate (TEOS), and ethanol. The fibers samples were carbonized at 550 °C in a static air atmosphere. PN-CSN fibers were characterized using scanning electron microscopy, N2 adsorption/desorption, X-ray diffraction, thermogravimetric analysis and zeta potential. The adsorption capacity was determined using a dye (methylene blue, MB). The PN-CSN fibers had a small average diameter (233 ± 178 nm), high specific surface area (364 m2 g−1) and pore volume (0.18 cm3 g−1). The pore size distribution ranged from 10 to 170 nm. Chemical analyses of the fibers revealed a residual amount of N (6.2%) and C (20,85%) as is characteristic in ceramic nanofibers made with polyacrylonitrile (PAN). The PN-CSN fibers had an adsorption capacity of approximately 400 mg g−1. The best fit for the adsorption data was found using a Langmuir model. The adsorption kinetics followed a pseudo-second order model. Thermodynamic analyses revealed the adsorption mechanism was endothermic and spontaneous for PN-CSN adsorbents.