The Preparation Of Silica Nanotubes Based On Electrospinning Technique And Their Applications

Due to their special surface effects and excellent stability, one-dimensional nanotubularfiber materials possess wide and deep applications in photovoltaic device, catalyst supports,energy, biomedicine and so on. As a kind of important inorganic materials, silica nanotubes(SNTs) exhibit prospective applications because of their large aspect ratio, high specific, surfacearea, good thermal stability, excellent biocompatibility, and easily-modified surface. Theconventional template methods preparing SNTs are low efficient and high cost, while theelectrospinning technique can effectively avoid these pitfalls. In the present investigtions, theelectrospinning technique is utilized to obtain SNTs with the specific surface area of411.58m2/g.Then we regulate the morphology of SNTs and study their formation mechanism. The fabricatedSNTs are employed as catalyst supports and adsorbents for heavy metal ions, discussing theirapplications in the degradation of organic dyes and adsorption of heavy metal ions, respectively.In the process of electrospinning, the solvent evaporation and phase separation can becontrolled by adjusting the precursor and technical specifications. When the solvent evaporationdominates the whole process, hollow C2H5OH/PVP/TEOS fibers with uniform size and preferredmorphology are acquired, which could be characterized by field emission scanning electronmicroscope (FESEM) and transmission electron microscope (TEM). And the pure SNTs can beprepared by calcining the hollow C2H5OH/PVP/TEOS fibers through temperature controlprogram. Additionally, the inner diameter of SNTs becomes larger with the increase of TEOS,and the ratios of the nanotubes diameter to the thickness of the nanotube wall (D/T) becomesmaller with the increase of calcinations rates.The SNTs were selected as catalysts carrier for TiO2nanoparticles, and the TiO2/SNTsheterostructures are synthesized by solvothermal method, TEM tests and N2adsorption-desorption results indicate that the new materials with the specific surface area of279.31m2/g exhibit obvious pore structure and high photocatalytic activities for the degradation of Rhodamine6G. More than90%of the organic dye can be degraded within90mins,meanwhile, the TiO2/SNTs heterostructures could be easily recycled without the distinct decreaseof the photocatalytic activity.SD-SNTs are acquired through the modification of SNTs by SD as while as utilizing thesolvent-nonsolvent method. Both SNTs and SD-SNTs are selected as adsorbents to study theiradsorption behaviors for Pb(II). From the results, the adsorption capacity of SNTs and SD-SNTsfor Pb(II) removal is found to be42.85and64.70mg/g, and their adsorption ability issignificantly improved with a decrease in pH value. SNTs exhibit high adsorption ability forPb(II) and the introduction of SD to the SNTs surface significantly increased the adsorptioncapacity and efficiency. A kinetic study is performed, which suggests that the adsorption of Pb(II)onto SNTs and SD-SNTs can be fitted to pseudo-first-order and pseudo-second-order model,respectively. The adsorption process of SNTs and SD-SNTs are monolayer adsorption, and theLangmuir adsorption model agrees well with the experimental data. The kinetics,thermodynamics, and X-ray photoelectron spectroscopy analysis (XPS) imply that theelectrostatic interactions play the major role in the adsorption of Pb(II) by SNTs, while thechelating interactions are the principal driving force for the adsorption of Pb(II) on SD-SNTs.