Advanced Materials Research Vols. 233-235

Abstract: In this paper, polypyrrole films doped with phosphomolybdic acid was prepared by bulk electrolysis with coulometry in the ScCO₂/Water emulsion system. The films were characterized by Raman and cyclic voltammetry methods. The polypyrrole structure was detected by Raman spectrum. And a stable oxidation-reduction behavior with three groups of peaks attributed to the phosphomolybdic acid doped in polypyrrole was established in the cyclic voltammetry curves. Moreover, the peak current was much better than that of the films prepared in conventional systems under constant pressure without the existence of ScCO₂.

Abstract: The adsorption thermodynamic and kinetic parameters of phenanthrene onto CTMA-bentonite were studied. The result shows that adsorption equilibrium time at their initial concentrations of 2 mg.L^-1 and 6 mg. L^-1 is 110 min. The dynamical data for the organoclay fit well with pseudo-second-order kinetic model at 303-333 K. The adsorption rates was found higher with the temperature increased, but its sorption extent was lower. Thermodynamic parameters such as ΔG⁰, ΔH⁰, ΔS⁰ were also evaluated. The overall adsorption process was spontaneous, exothermic physisorption. The isotherms for phenanthrene on the organoclay are linear and showed that partitioning was the dominant mechanism of phenanthrene on CTMA-bentonite.

Abstract: A variety of 3, 8-substituted cobalt (II) deuteroporphyrin dimethyl esters were synthesized and used as catalysts in the oxidation of cyclohexane. The effect of substituents on catalytic activities of 3, 8-substituted cobalt (II) deuteroporphyrin dimethyl esters were investigated. The results showed that the catalytic activities were influenced by the electron effects and steric effects of substituents and the thermal stability of catalysts.

Abstract: The traditional AlCl₃ catalyst was substituted by a new-type solid acidic catalyst AlCl₃/Al for the synthetic reaction of Fridel-Craft acylation from benzene and benzoyl chloride to diphenyl ketone. It has been showed that the yield of diphenyl ketone rising from 55% to 66%, hydrogen chloride emissions decreasing by 70.8%, and the new one being an environmental friendly catalyst.

Abstract: MgAl₂O₄ was respectively prepared by hydrothermal method (MgAl₂O₄-HT), co-precipitation method (MgAl₂O₄-CP) and solid reaction method (MgAl₂O₄-SR). The as-synthesized MgAl₂O₄ was used as support to prepare CoO_x/MgAl₂O₄ catalysts for the liquid phase oxidation of benzyl alcohol to benzaldehyde by H₂O₂. The catalytic performance and properties of these supports and catalysts were comparatively investigated by catalytic test, XRD, XRF, N₂ isothermal adsorption-desorption, TEM and H₂-TPR technologies. The properties of support MgAl₂O₄ was strongly depended on the preparation method of the support, which affected the catalytic activity of CoO_x/MgAl₂O₄ catalysts in the reaction. CoO_x/MgAl₂O₄-HT exhibited the higher catalytic reactivity and better reusability than CoO_x/MgAl₂O₄-CP and CoO_x/MgAl₂O₄-SR in the reaction, because MgAl₂O₄-HT was high-surface-area porous nanometer spinel MgAl₂O₄.

Abstract: LiFePO₄/C composites were synthesized by a novel carbothermal reduction method based on the low-temperature solution reaction between LiNO₃-Fe (NO₃)₃-NH₄H₂PO₄-sucrose. The sucrose amount, sintering temperature, sintering time, and heating temperature for synthesis of LiFePO₄/C cathode was optimized. The materials were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM) and charge–discharge tests. The results showed that sintering temperature and sucrose amount have more significant effects on discharge capacity than drying temperature and sintering time. Optimum LiFePO₄/C was prepared by sintering the precursor obtained by heating at 60 with a sucrose amount of 5.0g at 800.0 for 12 h. Being charged–discharged at 0.5C between 2.5 and 4.2 V, the LiFePO₄/C synthesized at the optimum conditions shows good electrochemical performances with an initial discharge capacity of 138.7 mAh·g⁻¹ and a capacity retention ratio of 98.6% after 50 cycles.

Abstract: For the first time a systematic research on the catalytic activity of CuX_n (X=Cl, Br, I; x=1,2) for the cross-coupling reaction of alkyl halides with Grignard reagents was carried out and environmentally friendly, economical CuBr₂ showed highest catalytic activity among the catalyst. The conditions of the cross-coupling reaction were studied. The suitable amount of catalyst, reaction temperature and time are 0.3% mol (based on alkyl halide), 67°C (reflux), 6 h, respectively. Under the optimal conditions, the yields of the cross-coupling could reach up to 93%. Moreover, Grignard reagent with an electron-rich group reacted rapidly and with an electron-withdrawing group reacted sluggishly.

Abstract: Li₃V₂(PO₄)₃/C has been synthesized by a simple one-step carbothermal reduction technology using LiH₂PO₄, V₂O₅ as the raw materials and sucrose as carbon source. X-ray diffraction (XRD) and scanning electron microscope (SEM) measurements showed that Li₃V₂(PO₄)₃/C synthesized by one-step carbothermal reduction had monoclinic structure. The structure and particle-size of the as-prepared Li₃V₂(PO₄)₃/C can be adjusted by the amount of carbon content, sintering temperature and sintering time in the synthesis processes. Li₃V₂(PO₄)₃/C prepared with a carbon content 0.4, sintering temperature 800°C and sintering time 20 h showed the largest discharge capacity 121.4mAh.g⁻¹ and an capacity retention rate of 98.3% after 50 cycles at 0.5C. The Li₃V₂(PO₄)₃/C obtained also exhibits an excellent rate capability with high discharge capacities of 111.0 mAh.g⁻¹ at 2.0C and 102.1 mAh.g⁻¹ at 5.0C.

Abstract: This study was designed to determine the heavy metal concentrations in soils and food crops and estimate the potential health risks of metals to polluted food crops and soil, so agricultural soil for the cultivation and taro were main objects of study, taro were taken in the HNO₃-H₂O₂ wet digestion, while soil were taken to HCl-HNO₃-HF-HClO₄ wet digestion by (ICP-OES),then coments and analysis on the samples were carried out by comparing with their limits of relative state standards. The analytical results indicate that for all of the analyzed elements the relative standard deviations (RSD) are 0.9-4.9% and the recoveries of most elements are in the range of 96.84-104.96%. Zn, As, Cd and other contents in soil samples were detectable beyond their limits of state standards, while heavy metals contents in the investigated samples were found at different polluted levels. Cd, Cr, As, Zn, Cu in taros also exceeded the national standard. It was found that there are enrichment of heavy metals in taro. It is concluded that the present techniques are suitable for the routine determination of heavy metals concentration in the food crops-soil systems.

Abstract: As well known, the weld line defect in injection molding process results detrimental to mechanical properties and surface quality. However, the electrical conductivity of the injection molded part is influenced as well. In this study, in order to reveal the mechanism of the weld line affecting the electrical conductivity of injection molding parts, the conductive polymer composites with various carbon nanofibers filling contents were compounded. Those composites were formed as the tensile samples with and without weld line defects by injection molding process. According to the electrical resistance measurements for the samples, it can be found that at relative low filling content of 10wt%, the weld line contributes to increase the electrical conductivity of the injection molding parts due to its effect on nanofibers’ orientation. However, when the filling content is higher than 20wt%, this effect is not significant any more.