PWR核电站蒸汽发生器停堆湿保养工况联氨的缓蚀作用

一、引言压水堆(PWR)核电站蒸汽发生器(SG)管材因二回路系统腐蚀产物积累发生应力腐蚀开裂,这是SG传热管破损的主要原因之一。维修和更换SG使PWR停运期间所需要的替用电力对发电站造成很大的财政负担,同时,二回路系统的腐蚀产物沉积在蒸汽发生器内,降低     

Hematoxylin multi-wall carbon nanotubes modified glassy carbon electrode for electrocatalytic oxidation of hydrazine

A new hydrazine sensor has been fabricated by immobilizing hematoxylin at the surface of a glassy carbon electrode (GCE) modified with multi-wall carbon nanotube (MWCNT). The adsorbed thin films of hematoxylin on the MWCNT modified GCE show one pair of peaks with surface confined characteristics. The hematoxylin MWCNT (HMWCNT) modified GCE shows highly catalytic activity toward hydrazine electro-oxidation. The results show that the peak potential of hydrazine at HMWCNT modified GCE surface shifted by about 167 and 255 mV toward negative values compared with that at an MWCNT and activated modified GCE surface, respectively. In addition, at HMWCNT modified electrode surface remarkably improvement the sensitivity of determination of hydrazine. The kinetic parameters, such as the electron transfer coefficient, α, and the standard heterogeneous rate constant, k⁰, for oxidation of hydrazine at the HMWCNT modified GCE were determined and also is shown that the heterogeneous rate constant, k′, is strongly potential dependent. The overall number of electron involved in the catalytic oxidation of hydrazine and the number of electrons involved in the rate-determining steps are 2 and 1, respectively. The amperometric detection of hydrazine is carried out at 220 mV in 0.1 M phosphate buffer solution (pH 7) with linear response range 2.0-122.8 μM hydrazine, detection limit of 0.68 μM and sensitivity of 0.0208 μA μM⁻¹. Finally the amperometric response for hydrazine determination is reproducible, fast and extremely stable, with no loss in sensitivity over a continual 400 s operation.     

Electrochemical determination of hydrazine based on polydopamine-reduced graphene oxide nanocomposite

In this work, a simple and mild procedure was employed to synthesize polydopamine-reduced graphene oxide (PDA-RGO) nanocomposites, where the sheets of graphene oxide were functionalized firstly with PDA through self-polymerization. FTIR was used to confirm that the GO sheets had been functionalized successfully with PDA and reduced. Besides, UV-Vis and X-ray diffraction spectroscopy were employed to further demonstrate the formation of RGO. The electrochemical property of the PDA-RGO has been studied by the determination of hydrazine. The results indicated that the electrochemical oxidation of hydrazine was significantly improved by the obtained PDA-RGO nanocomposite due to the increased available surface area of electrode. A quick amperometric response was observed with the electrochemical sensor based on PDA-RGO nanocomposite for the hydrazine measurement in a wide linear range of 0.03–100 μM, where the limit of the detection was 0.01 μM.     

A sensitive hydrazine electrochemical sensor based on electrodeposition of gold nanoparticles on choline film modified glassy carbon electrode

A highly sensitive hydrazine sensor was developed based on the electrodeposition of gold nanoparticles onto the choline film modified glassy carbon electrode (GNPs/Ch/GCE). The electrochemical experiments showed that the GNPs/Ch film exhibited a distinctly higher activity for the electro-oxidation of hydrazine than GNPs with 3.4-fold enhancement of peak current. The kinetic parameters such as the electron transfer coefficient (α) and the rate of electron exchange (k) for the oxidation of hydrazine were determined. The diffusion coefficient (D) of hydrazine in solution was also calculated by chronoamperometry. The sensor exhibited two wide linear ranges of 5.0 × 10⁻⁷-5.0 × 10⁻⁴ and 5.0 × 10⁻⁴-9.3 × 10⁻³ M with the detection limit of 1.0 × 10⁻⁷ M (s/n = 3). The proposed electrode presented excellent operational and storage stability for the determination of hydrazine. Moreover, the sensor showed outstanding sensitivity, selectivity and reproducibility properties. All the results indicated a good potential application of this sensor in the detection of hydrazine.     

Rubidium hydrazinidoborane: Synthesis,characterization and hydrogen release properties

In this work we present rubidium hydrazinidoborane RbN₂H₃BH₃ (RbHB), the newest and last member of the alkali metal derivatives of hydrazine borane N₂H₄BH₃ (HB). It is shown that HB readily reacts with metallic rubidium in THF at room temperature to form RbHB under argon atmosphere. The molecular and crystal structures of this new compound are discussed on the basis of FTIR spectroscopy, ¹¹B MAS NMR spectroscopy, and powder X-ray diffraction analyses. RbHB crystallizes in a monoclinic P2₁ (No. 4) unit cell where each Rb⁺ cation adopts octahedral coordination surrounded by six [N₂H₃BH₃]⁻ anions, which are two more than for e.g. LiN₂H₃BH₃ (with tetrahedral coordination) in accordance with the larger size of Rb⁺. RbHB is isostructural to potassium hydrazinidoborane KN₂H₃BH₃. Its dehydrogenation properties, evaluated by using thermogravimetric analysis, differential scanning calorimetry, and isothermal analysis, are compared to those of the parent HB as well as to analogous compounds in order to evaluate the potential of RbHB as hydrogen storage material. According to the presented data, the dehydrogenation properties of RbHB are much better than those of HB and are comparable to those of the lithium derivative. Our main results are reported therein.     

高含量哒螨灵原药合成研究

以叔丁基肼水溶液、糠氯酸为原料,在甲苯做溶剂、冰乙酸做催化剂条件下经成腙、闭环、脱溶,然后在水相结晶制得高含量2-叔丁基-4,5-二氯-3(2H)-哒嗪酮(以下简称哒嗪酮);哒嗪酮再与对叔丁基苄硫醇在甲醇做溶剂的条件下经缩合、脱甲醇、水相结晶制得高含量哒螨灵原药。反应具有操作稳定、收率高的优点,缩合反应在低温下进行,有利于提高产品质量及收率;哒螨灵在一定浓度的稀碱水溶液中结晶,其含量可达到96%以上。该方法具有产品质量高、成本低的优点,适合工业化生产。     

基于BP网络模型的水合肼合成收率预测及参数优杞

采用BP算法建立了水合肼合成收率的神经网络模型，所建网络有良好的回想和泛化性能，对水合肼合成收率预测的平均相对误差小于0．5％。运用网络模型考察了反应温度、物料配比、次氯酸钠流量等操作参数对水合肼合成收率的影响，同时确定了获得较高合成收率时各操作参数的优化值。     

Characterization of cobalt oxide nanocatalysts prepared by microemulsion with different surfactants, reduction by hydrazine and mechanochemical method

Cobalt oxide (Co₃O₄) nanoparticles were prepared by different techniques (i) by microemulsion with different surfactants, (ii) by reduction as nanometal with hydrazine hydrates and (iii) by thermal treatment of precursor obtained from mechanochemical reaction of Co(NO₃)·H₂O with NH₄HCO₃. The products were calcined at 400 °C to give crystalline Co₃O₄. The obtained different samples of Co₃O₄ were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM) from which the particle size was calculated. The results revealed that all samples obtained from different methods were nanosized particles.     

水合肼还原氧化石墨烯的研究

通过改进的Hummers法制备氧化石墨,将获得的氧化石墨进行热剥离以及超声剥离得到双层甚至单层的氧化石墨烯片.然后采用化学还原-水合肼还原的方法去除氧化石墨烯所含的羧基COOH、羟基OH、羰基C=O和环氧基等化学基团.本实验着重研究了还原剂的用量和反应时间对各个化学基团的影响规律.