Poly(ethylene-co-vinyl alcohol) (EVOH) nanofibers with average diameter of 260 nm were initially fabricated through the melt-blending extrusion of immiscible blends. The resulting films obtained by layer deposition technology were then functionalized by in situ oxidative polymerization of pyrrole monomer in hydrochloric acid solution for hexavalent chromium [Cr(VI)] adsorption from water. Scanning electron microscopy and Fourier-transform infrared spectroscopy were used to characterize the morphology and structure of functionalized nanofiber membranes. Adsorption experiments were conducted to test the effects of solution pH, dose of adsorbents, water temperature, adsorption contact time, and initial concentration of Cr(VI) and to determine the Cr(VI) adsorption mechanism. The experimental results denoted that the adsorption process was endothermic, spontaneous, and highly pH dependent, and the kinetics data fitted well with a pseudo-second-order model. The adsorption equilibrium time was less than 100 min, and the maximum adsorption capacities were 90.74 mg/g from the adsorption kinetics study. The adsorption isotherm data followed the Langmuir isothermal model. Desorption results exhibited excellent reusability of the membrane for Cr(VI) adsorption.
In this article, polymer blends of polylactide (PLA) and co-polyester (co-PET) were prepared at various weight ratios of PLA/co-PET, such as 10/90, 20/80, 30/70, and 40/60, through a twin-screw extruder. The PLA nanofibers were fabricated by removal of the co-PET matrix in water at 80 C. The morphology development of PLA dispersed phase obtained from the three different sample connections and the die of the twin-screw extruder were investigated by Scanning Electron Microscopy (SEM). It was found that the uniformed PLA nanofibers with averaged diameters less than 500 nm were fabricated by the suitable processing parameters. The processing immiscibility and rheological behavior of PLA/co-PET blends were also studied by means of Differential Scanning Calorimeter (DSC) and Capillary Rheometer. The test of Fourier Transform Infrared spectroscopy (FTIR) demonstrated that the co-PET was removed clearly in water at 80 C.
High flux PP/EVOH nanofibrous composite microfiltration membrane (P/E‐NCMM) based on polypropylene (PP) (575 nm) and polyethylene‐co‐polyvinyl alcohol (EVOH) nanofibers (248 nm) with low operation pressure for liquid filtration was fabricated by melt blending extrusion. PP nanofibers as the scaffold played a supporting role, and EVOH nanofibers filled in the PP nanofibers network structure narrowed the pore size and improved the wettability. Taking advantages of PP and EVOH nanofibers, the nanofibrous composite membrane created fascinating features for liquid filtration. The experimental results showed that the P/E‐NCMM had high average pure water flux at low operating pressure. The P/E‐NCMM with 30 wt % PP nanofibers showed high water flux [450.9 L/(m2 h)] even at very low feeding pressure (0.05 MPa) with above 95% retention for TiO2 suspension. The results indicated that the P/E‐NCMM prepared by this method had great potential for the application in liquid filtration. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43585.
Durability is an issue for selective catalytic reduction (SCR) catalysts due to their susceptibility to sulfur and water poisoning. In this study, Nano-Ce 10 -PSDC HF /ZrO 2 was prepared by the hydrothermal method using sintering dust, and the impact of SO 2 or water vapor on its SCR performance was investigated. The denitrification performance of Nano-Ce 10 -PSDC HF /ZrO 2 was better than that of 0.25-Ce 10 -PSDC HF /ZrO 2 prepared by the impregnation method in the entire temperature interval from 80 to 400 °C. The highest denitrification rate of 93.6% was achieved at 280 °C. Nano-Ce 10 -PSDC HF /ZrO 2 had a smaller particle size and uniform dispersion but also formed a high concentration of Ce 3+ and adsorbed oxygen O α on the surface. Additionally, it showed better resistance to water and sulfur than 0.25-Ce 10 -PSDC HF /ZrO 2 . Even when exposed to 8% H 2 O and 400 ppm SO 2 , the denitrification rate of Nano-Ce 10 -PSDC HF /ZrO 2 remained at 82.1% after 4 h. SO 2 is more toxic to SCR catalysts than H 2 O. The effect of water on catalyst activity is partially reversible. Deactivation of SCR by SO 2 is primarily caused by the formation of ammonium sulfate species, with some contribution from competitive adsorption between SO 2 and NO x . In conclusion, the Nano-Ce 10 -PSDC HF /ZrO 2 catalyst exhibited the best SCR performance, with water and sulfur resistance, and effectively utilized sintering dust, which has potential application value.
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