Silica and N-Carbon/Silica hybrid nanofiber obtained by solution blow spinning (SBS) to dye adsorption

Reference	Presenter	Authors (Institution)	Abstract
06-112	Raquel Santos Leite	Farias, R.M.(Universidade Federal de Campina Grande); Leite, R.S.(Universidade Federal de Campina Grande); Severo, L.L.(Universidade Federal de Campina Grande); Neves, G.A.(Universidade Federal de Campina Grand); Glenn, G.M.(Bioproduct Research Unit USDA-ARS, WRRC); Medeiros, E.S.(UFPB); Menezes, R.R.(Universidade Federal de Campina Grande);	Adsorption is an important technology to remove dye from wastewater due to its effectiveness, simplicity and low cost. Lately, nanofibers have been used as an adsorbent in adsorption process due to its unique microstructure and properties. Solution blow spinning (SBS) is a promising technique to obtain ceramic nanofibers. The goal of this work was to produce SiO2 and N-C/SiO2 nanofibers based on a solution containing polyvinylpyrrolidone (PVP) and tetraethylorthosilicate (TEOS) by SBS to remove methylene blue from aqueous solution. The as-spun nanofibers were calcined at 550°C in air for 1h. To obtain N-C/SiO2 hybrid the crucible was covered to restrict the flow of oxidizing atmosphere inside. The samples were characterized by Scanning Electron Microscope (SEM), X-ray diffraction (XRD), BET and CHN elemental analysis. The remaining amount of dye in the solution after the adsorption experiments was estimated using UV-Spectrometry at a wavelength of 664nm. All isotherm studies were done at pH10. According to the results, SEM micrographs showed that the fibers present elongated and uniform fibers with average diameter 176 ± 90nm and 241 ± 143nm to SiO2 and N-C/SiO2, respectively. The XRD showed a characteristic band of amorphous silica and of both samples. The SiO2 nanofibers presented 0,65% (C) and 0,54% (N) and N-C/SiO2 nanofibers presented 21% (C) and 6,2% (N). BET surface area of 342 and 227 m2/g to SiO2 and N-C/SiO2, respectively. The maximum adsorption capacity was found to be 279 mg/g at 25 °C for SiO2 and 405 mg/g at 45 °C for N-C/SiO2. Equilibrium adsorption data followed Langmuir isotherms. Kinetic adsorption followed a second-order model. The thermodynamic study carried out at 25-45 °C showed the exothermic and endothermic reactions for SiO2 and N-C/SiO2, respectively. These adsorbent nanofibers have potential on removing methylene blue from aqueous solution. The presence of C and N in silica nanofibers play an important role in the adsorption process.
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