Advanced Materials Research Vols. 396-398

Abstract: A two-step reaction approach in alcohol, which comprised a step of monochoroacetic acid reacting with ammonia and a step of the resulted ammonium monochloroacetate reacting with ammonia in presence of urotropine as catalyst, was employed to synthesize glycine. Operating conditions for synthesizing glycine and for purifying glycine product were investigated through intensive experimental approach. The optimal operating conditions for the whole process including synthesis and purification of glycine were obtained and tested. Under such conditions, for methanol as reaction media and for methanol aqueous solution as separating agent, the glycine product yield reaches 92.9% with a purity of 99.7%, whereas for methanol as reaction media and for ethanol aqueous solution as separating agent, the glycine product yield is 89.5% with a purity of 98.6%.

Abstract: Drip fertigation was applied to evaluate the effects on nutrient losses and crop production in a pear orchard at Chongming Dongtan in Yangtze River Estuary in 2006 and 2007, compared to conventional irrigation and fertilization practices. Based on runoff paddocks and leaching pipes construction, the volumes of runoff and leaching water, and the corresponding concentrations of nitrogen and phosphorus were measured and estimated. The results indicated that, under the experimental conditions, N and P losses through runoff and leaching occurred mainly in the period of rain season from June to October, and leaching was the dominating pathways for N loss while runoff was the main pathways for P loss. Compared with the conventional irrigation and fertilization system, under the consistency of crop yields, the drip fertigation system could decrease the total amounts of nitrogen and phosphorus losses through runoff and leaching by 36.4% and 16.5%, and reduce the total amounts of nitrogen and phosphorus consumptions of chemical fertilizer application by 73.4% and 61.1%, respectively.

Abstract: A novel ZnO/ZnO-Bi2O3 nanocomposite was prepared by a homogeneous precipitation method. The nucleation sites, namely ZnO-Bi2O3 particles with nominal chemical composition of (ZnO)0.94(Bi2O3)0.06, were prepared by ball milling and subsequent annealing treatment. The as-synthesized materials were characterized by XRD, SEM and electrochemical measurements. Compared with single ZnO, the ZnO/ZnO-Bi2O3 nanocomposite show better cycling stability and higher discharge capacity. When the content of ZnO-Bi2O3 was 15 wt.%, the discharge capacity of ZnO/ZnO-Bi2O3 nanocomposite hardly declined over 60 cycling test, the average discharge capacity reached 590.2 mAh g−1. Cyclic voltammograms clearly illuminated that the added ZnO-Bi2O3 particles could decrease electrode polarization, maintain the electrochemical activity, and enhance the discharge capacity of ZnO.

Abstract: Electrochemical oxidation of tiron in the presence of H2O as a nucleophile in strongly acidic aqueous solutions was studied by cyclic voltammetry, controlled-voltage coulometry and spectrometric investigations. The mechanism of electrochemical reaction is confirmed by spectrophotometric tracing in various times of controlled-voltage coulometry. The voltammetric and spectrophotometric foundations indicate that a 1,4-Michael addition of H2O from its hydroxy moiety to the position 4 of electrochemically derived o-quinone is occurred. The electrochemical oxidation and reduction of tiron has been successfully accomplished by controlled-voltage coulometry in a redox flow-through type cell and the final electro-reduced product was characterized by spectrophotometric, 1H NMR and mass spectrometric methods. It is demonstrated that the electro-oxidation of tiron follows an ECE mechanism in acidic aqueous solutions, leading to formation of a new compound of para- benzoquinone derivative.

Abstract: In this work structured sheet metals were investigated using electrochemical measurement techniques. The main purpose is obtaining fundamental information about the corrosion resistance of structured sheet metals in comparison to smooth sheet metals as well determination of the influence of the structuring process on the corrosion properties. The corrosion resistance of structured sheet metals is affected by manufacturing process. One of the main influence factors is the change of the surface roughness. In this study the low carbon steel DC04 and the stainless steel 304 (X5CrNi18-10) were investi-gated. The electrochemical tests were carried out in 3%-NaCl solution. Potentiodynamic linear polarization was used to determine such electrochemical characteristics as the free corrosion potential, the corrosion current, the pitting and protection potential. Furthermore, the corrosion rate was calculated for smooth and structured sheet metals of the low carbon steel DC04. For the stainless steel 304 the pitting density was estimated. The surface roughness was measured for both materials. The electrochemical corrosion tests show a small difference in the corrosion behaviour of structured and smooth sheet metals. Structured sheet metals have a lower corrosion resistance than smooth sheet metals. The steel DC04 shows the worst corrosion properties at the structure location “negative” in comparison to the structure location “positive”. The corrosion resistance of the stainless steel 304 is better at the structure location “negative” than at the structure location “positive”. Moreover, the results show the correlation between the surface roughness and the corrosion resistance for structured sheet metals.

Abstract: A bright tin coating was prepared by electrodeposition method in the electroplating system of methanesulfonic acid. The effects of methylsulfonic acid concentration, main salt concentration, current density and brightener on brightness of coating were investigated by orthogonal experiment. A plating process of bright tin was confirmed: concentration of methylsulfonic acid: concentration of Sn2+: current density: 2.5A/dm2, dosage of brightener: at the same time, current efficiency, throwing power, covering power and electrochemical behavior for the process were inspected systematically. And the coatings are characterized by X-ray diffraction analysis (XRD) and scanning electron microscope (SEM).

Abstract: A new kind of cathode materials, Li3V2(PO4)3/C nanocomposites, has been prepared via one-step solid-state reaction using ultra low-cost asphalt as both reduction agents and carbon sources. The asphalt is contained 60.37% of fixed carbon and 0.18% of other impurity.It is purchased from Zhen jiang Xin Guang Metallurgical Subsidiary Material Plant. Structural analysis shows that the obtained Li3V2(PO4)3/C nanocomposites contain abundant Li3V2(PO4)3 nanorods and micro/nano particles encapsulate with carbon shells. The Li3V2(PO4)3/C nanocomposites achieve enhanced dischargeability, reversibility, and cycleability. Electrochemical tests show that the Li3V2(PO4)3/C nanocomposite has initial discharge capacities of 170 mAhg-1 at 0.1C in the voltage range of 3.0 to 4.8 V. The improved electrochemical properties of the Li3V2(PO4)3/C nanocomposites are attributed to the presence of Li3V2(PO4)3/C nanorods and the electronically conductive carbon shell. This one-step solid state reaction using low-cost asphalt as carbon sources is feasible for the preparation of the Li3V2(PO4)3/C nanocomposites which can offer favorable properties for commercial applications.

Abstract: A acrylonitrile (AN)-methyl acrylate (MMA)-methoxy polyethylene glycol(350) monoacrylate (MPGA)-lithium acrylate (LiAc) tetra-copolymer was synthesized by emulsion polymerization, and phase inversion technique was adopted to prepare the as prepared polymer based microporous membrane. The gel polymer electrolytes (GPEs) were obtained by soak the as-prepared microporous membrane into 1M LiPF6/ (EC (ethylene carbonate) + DEC (diethylene carbonate)) (1:1 vol) electrolyte. FTIR, NMR and TGA/DSC measurements are used to character the components and structure of the polymer. The GPE’s ionic conductivity exceeds 3.0×10-3S/cm at ambient temperature, and this system also shows a sufficient electrochemical stability with a decomposition voltage as much as 6.0V vs Lithium(Li)/Li+ to allow far wider operation in the rechargeable lithium-ion polymer batteries. What’s more, this membrane also shows good characters in battery’s charge-discharge cycles.

Abstract: The anticorrosive performances of various kinds of conversion films including hexavalent and trivalent chromium passivation were studied on galvanized steel. The hexavalent and trivalent passivations showed similar protection tendency in the corrosion tests, but the hexavalent passivation had slightly better results than trivalent one. It was found the difference in the corrosion resistance given by the two films was attributed to the difference of their morphology and thickness by SEM test, for the hexavalent film was denser, smoother and thicker. Using EDS and XRD experiments, it was found that the hexavalent and trivalent passive films had the same chemical element but different components. Considering the environmental protection, the trivalent passivation will have better developing prospect in the near future.

Abstract: In this work, Chromium (Cr(III)) conversion coatings on Al 6063 alloy was prepared using trivalent-chrome compound (KCr(SO4)2) and H3PO4. The influence of five variables (i.e. deposition temperature, time, bath pH, and concentrations of (Cr(III)) compound (KCr(SO4)2) and H3PO4) on the preparation of (Cr(III)) coating on Al 6063 alloy was investigated using polarization curve in 3.5 wt% NaCl solution. The parameters of polarization curves were obtained from the extrapolation of anodic and cathodic Tafel lines. The optimum chemical passivation parameters of the chromium (Cr((III)) conversion coatings on the 6063 Al surface were obtained in this paper The results show the chromium (Cr(III)) conversion coatings formed under the optimal range present better corrosion resistance than those under the other conditions. Proper mechanisms were proposed to explain the above electrochemical behavior for the five treated conditions.