Fabrication of hollow and nonhollow SiO₂ nanofibers for removal of cationic dyes from aqueous solutions

Abstract

In this work, SiO 2 hollow (HNF) and non-hollow (nHNF) nanofibers were successfully fabricated and optimized by combination of electrospinning, sol-gel and thermal decomposition methods depending. The wall thickness of the HNF was in the range of 10-26 nm depended to the average diameter of the template. The thermal decomposition occurred at two different temperatures of 530 and 10308C. The effects of the electrospinning conditions, the concentration of SiO 2 precursor, and thermal decomposition temperature on the nanofibers morphology were investigated by scanning electron microscopy. The influence of hollow morphology on crystalline phase, thermal resistance, surface charge and BET surface area were investigated by X-ray diffraction, thermography analysis, zeta potential, and Brunauer-Emmett-Teller (BET) analyses, respectively. In addition, the chemical changes occurred in the sol-gel process were determined by Fourier transform infrared spectroscopy. The result showed higher weight loss and BET surface area values for HNF in comparison to the nHNF after thermal decomposition process. According to results, the temperature applied in thermal decomposition process had a direct influence on properties of nanofibers. Dye removal ability of synthesized nanofibers was investigated by considering adsorption dosage, pH, and dye concentration. Also, the dye adsorption isotherm and kinetic were studied. Nonlinear regression was used to determine the best fit model for each system. To do this, 3 error functions were applied to predict the optimum model. Among various isotherm models, Langmuir model represented the equilibrium adsorption data while kinetic experimental data were well fitted by pseudosecond-order model on both adsorbents.

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