Montmorillonite supported titanium （Ti-MMT） or antimony catalyst （Sb-MMT） has been a hot area of research on preparing polyethylene terephthalate/montmorillonite （PET/MMT） nanocomposites by in situ polymerizatio...Montmorillonite supported titanium （Ti-MMT） or antimony catalyst （Sb-MMT） has been a hot area of research on preparing polyethylene terephthalate/montmorillonite （PET/MMT） nanocomposites by in situ polymerization. So removal of Ti or Sb from Ti-MMT or Sb-MMT is not expected during in situ polymerization. Studies on immobilization of Ti or Sb on Ti-MMT or Sb-MMT are seldom reported. In this work, a series of montmorillonite supported catalysts of titanium （Ti-MMT） or antimony （Sb-MMT） and cointercalated montmorillonite of titanium and antimony （Ti/Sb-MMT） were prepared by （1） the reaction of sodium bentonite suspension with intercalating solution containing titanium tetrachloride and/or antimony chloride, and （2） drying or calcinating the products at different temperature （100, 150, 240, 350 and 450 ℃）. The physicochemical properties of these MMT supported catalysts were studied by X-ray diffraction （XRD）, fourier transform infrared spectroscopy （FT-IR）, inductively coupled plasma optical emission spectrometer （ICPOES）, N2 adsorption/desorption isotherms, UV-visible diffuse reflectance spectroscopy（UV-vis） and transmission electron microscopy （TEM）. The immobile character of Ti or Sb on MMT supported catalysts was evaluated by a two-step method in deionized water or ethylene glycol. Several results were obtained, i e, （a） during the preparation, with an increase in drying or calcinating temperature, the amount of titanium and/or antimony species remained on these MMT supported catalysts decreased, （b） the experiments about immobile character of Ti or/and Sb showed that with an increase in drying or calcinating temperature, the immobilization of Ti and/or Sb species remained on these MMT supported catalysts increased gradually, （c） Ti-MMT calcinated at 450℃ had the biggest pore volume, which means Ti-MMT had the best adsorption application prospect.展开更多
In this study, the ionic conductivity behavior in hybrid gelatin-based transparent electrolytes including various types of nanoclays with different size, shape and surface properties was characterized. The effects of ...In this study, the ionic conductivity behavior in hybrid gelatin-based transparent electrolytes including various types of nanoclays with different size, shape and surface properties was characterized. The effects of nanoclay type and nanoclay concentration as well as different experimental conditions, e.g., pH, temperature and crosslinking were also investigated. In general, the impedance spectroscopy results suggested a non- trivial role for nanoclay. Regardless of the nanoclay type, the ionic conductivity slightly increased first and then decreased by increasing the nanoclay concentration. Furthermore, among sodium montmorillonite （Na＋MMT）, lithium montmorillonite （Li＋MMT）, laponite and hydrotalcite, the hybrid electrolytes prepared by Li＋MMT showed higher ionic conductivity. The results also showed that the chemical crosslinking along with sample preparation at optimum pH, where the gelatin chains might be efficiently adsorbed on exfoliated, negatively charged clay nanosheets, plays an important role. In comparison with the ionic conductivity of the neat sample at room temperature （～10-7 S cm-1）, a ten-fold increase was observed for the crosslinked sample containing 2 wt% of Li^＋MMT prepared at optimum pH 3.5. The conductivity behavior as a function of temperature revealed the obedience with the VogeI-Fulcher-Tammann （VFT） model for all samples, suggesting the important role of segmental motions in the ionic conductivity. Finally, a qualitative explanation was presented for the mechanism of the ionic conduction in gelatin-nanoclay hybrid electrolytes.展开更多
文摘Montmorillonite supported titanium （Ti-MMT） or antimony catalyst （Sb-MMT） has been a hot area of research on preparing polyethylene terephthalate/montmorillonite （PET/MMT） nanocomposites by in situ polymerization. So removal of Ti or Sb from Ti-MMT or Sb-MMT is not expected during in situ polymerization. Studies on immobilization of Ti or Sb on Ti-MMT or Sb-MMT are seldom reported. In this work, a series of montmorillonite supported catalysts of titanium （Ti-MMT） or antimony （Sb-MMT） and cointercalated montmorillonite of titanium and antimony （Ti/Sb-MMT） were prepared by （1） the reaction of sodium bentonite suspension with intercalating solution containing titanium tetrachloride and/or antimony chloride, and （2） drying or calcinating the products at different temperature （100, 150, 240, 350 and 450 ℃）. The physicochemical properties of these MMT supported catalysts were studied by X-ray diffraction （XRD）, fourier transform infrared spectroscopy （FT-IR）, inductively coupled plasma optical emission spectrometer （ICPOES）, N2 adsorption/desorption isotherms, UV-visible diffuse reflectance spectroscopy（UV-vis） and transmission electron microscopy （TEM）. The immobile character of Ti or Sb on MMT supported catalysts was evaluated by a two-step method in deionized water or ethylene glycol. Several results were obtained, i e, （a） during the preparation, with an increase in drying or calcinating temperature, the amount of titanium and/or antimony species remained on these MMT supported catalysts decreased, （b） the experiments about immobile character of Ti or/and Sb showed that with an increase in drying or calcinating temperature, the immobilization of Ti and/or Sb species remained on these MMT supported catalysts increased gradually, （c） Ti-MMT calcinated at 450℃ had the biggest pore volume, which means Ti-MMT had the best adsorption application prospect.
基金supports from the Iranian Nanotechnology Initiative 41118/1390.03.31the vice-president for Research and Technology of the University of Tehran are gratefully appreciated
文摘In this study, the ionic conductivity behavior in hybrid gelatin-based transparent electrolytes including various types of nanoclays with different size, shape and surface properties was characterized. The effects of nanoclay type and nanoclay concentration as well as different experimental conditions, e.g., pH, temperature and crosslinking were also investigated. In general, the impedance spectroscopy results suggested a non- trivial role for nanoclay. Regardless of the nanoclay type, the ionic conductivity slightly increased first and then decreased by increasing the nanoclay concentration. Furthermore, among sodium montmorillonite （Na＋MMT）, lithium montmorillonite （Li＋MMT）, laponite and hydrotalcite, the hybrid electrolytes prepared by Li＋MMT showed higher ionic conductivity. The results also showed that the chemical crosslinking along with sample preparation at optimum pH, where the gelatin chains might be efficiently adsorbed on exfoliated, negatively charged clay nanosheets, plays an important role. In comparison with the ionic conductivity of the neat sample at room temperature （～10-7 S cm-1）, a ten-fold increase was observed for the crosslinked sample containing 2 wt% of Li^＋MMT prepared at optimum pH 3.5. The conductivity behavior as a function of temperature revealed the obedience with the VogeI-Fulcher-Tammann （VFT） model for all samples, suggesting the important role of segmental motions in the ionic conductivity. Finally, a qualitative explanation was presented for the mechanism of the ionic conduction in gelatin-nanoclay hybrid electrolytes.
