高中化学创新实验课程的设计与实施*

将学生所学的化学理论知识与生活实际和学科最前沿的研究热点相结合,开发并实施了 “氢氧化镁纳米材料的制备及其在处理重金属废水中的应用” 创新实验课程。该课程通过文献调研、方案设计、实验操作、结果与讨论以及论文撰写等环节,激发学生的创新潜能,系统培养学生的创新综合素质和责任意识,这有助于更好地达成化学学科核心素养。     

Mechanochemical synthesis of PbS/Ni–Cr layered double hydroxide nanocomposite

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Modified Preparation of 99mTe-Iron Hydroxide Macroaggregate (99mTe-Fe-(OH)2MA)

A modified method for preparing ^99mTc-FHMA for pulmonary studies is elabrated. It includes a new antioxidant sodium metabisulphite. The optimum conditions for the reparation are given. A simple and rapid procedure with a yield more than 98% is described which eliminates a further purification step.     

Flammability and Thermal Oxidative Degradation Kinetics of Magnesium Hydroxide and Expandable Graphite Flame Retarded Polypropylene Composites

The flammability and the thermal oxidative degradation kinetics of expandable graphite (EG) with magnesium hydroxide (MH) in flame‐retardant polypropylene (PP) composites were studied by limiting oxygen index (LOI), UL‐94 test, and thermogravimetric analysis (TGA). The results show that EG is a good synergist for improving the flame retardancy of PP/MH composite and the effect is enhanced with decreasing EG particle size. The Kissinger method and Flynn‐Wall‐Ozawa method were used to determine the apparent activation energy (E) for degradation of PP and flame retarded PP composites. The data obtained from the TGA curve indicate that EG markedly increases the thermal degradation temperature of PP/MH composites and improves the thermal stability of the composites. The kinetic results show that the values of E for degradation of flame retarded PP composites is much higher than that of neat PP, especially PP/MH composites with suitable amount of EG, which indicates that the flame retardants used in this work have a great effect on the mechanisms of pyrolysis and combustion of PP.     

CP@NiAl-LDH复合材料的制备及其超级电容器性能

通过采用简易温和的水热条件制备导电聚合物@镍铝层状双金属氧化物复合材料（CP@NiAl-LDH）,构建电子/离子的高速传输纳米通道,利用SEM和XRD对复合材料结构形貌进行表征。电化学性能测试结果表明,导电聚合物为复合材料提供一定的赝电容,促进电荷的快速转移,使CP@NiAl-LDH的电容性能得以显著提升。PPy@LDH具有最好的电容性能,在1 A·g^-1的电流密度下,其比容量高达3 010.3 F·g^-1,当电流密度升高到20 A·g^-1时,其比电容保持率为73.1%,表现出优异的倍率性能;同时,在10 A·g^-1的电流密度下10 000次充放电循环后仍具有88.8%的比容量保持率,具有优异的循环稳定性。这主要归功于NiAl-LDH与导电聚合物之间的协同增强效应。     

Triton-B-Catalyzed,Efficient, One-Pot Synthesis of Dithiocarbazates Through Alcoholic Tosylates

A quick, efficient, one-pot synthesis of dithiocarbazates was accomplished in high yields by the reaction of various tosylates of primary, secondary, and tertiary alcohols with a variety of substituted hydrazines using the benzyl–trimethylammonium hydroxide (Triton-B)/CS₂ system. The reaction conditions are mild with simpler workup procedures than the reported methods.     

Nonisothermal crystallization and morphology of poly(butylene succinate)/layered double hydroxide nanocomposites

Biodegradable poly(butylene succinate) (PBS) and layered double hydroxide (LDH) nanocomposites were prepared via melt blending in a twin-screw extruder. The morphology and dispersion of LDH nanoparticles within PBS matrix were characterized by transmission electron microscopy (TEM), which showed that LDH nanoparticles were found to be well distributed at the nanometer level. The nonisothermal crystallization behavior of nanocomposites was extensively studied using differential scanning calorimetry (DSC) technique at various cooling rates. The crystallization rate of PBS was accelerated by the addition of LDH due to its heterogeneous nucleation effect; however, the crystallization mechanism and crystal structure of PBS remained almost unchanged. In kinetics analysis of nonisothermal crystallization, the Ozawa approach failed to describe the crystallization behavior of PBS/LDH nanocomposites, whereas both the modified Avrami model and the Mo method well represented the crystallization behavior of nanocomposites. The effective activation energy was estimated as a function of the relative degree of crystallinity using the isoconversional analysis. The subsequent melting behavior of PBS and PBS/LDH nanocomposites was observed to be dependent on the cooling rate. The POM showed that the small and less perfect crystals were formed in nanocomposites.     

Total and inorganic mercury determination in fish tissue by flow injection cold vapour atomic fluorescence spectrometry

A simple and reliable method for Hg determination in fish samples has been developed. Lyophilised fish tissue samples were extracted in a 25% (w/v) tetramethylammonium hydroxide (TMAH) solution; the extracts were then analysed by FI-CVAFS. This method can be used to determine total and inorganic Hg, using the same FI manifold. For total Hg determination, a 0.1% (w/v) KMnO₄ solution was added to the FI manifold at the sample zone, followed by the addition of a 0.5% (w/v) SnCl₂ solution, whereas inorganic Hg was determined by adding a 0.1% (w/v) L-cysteine solution followed by a 1.0% (w/v) SnCl₂ solution to the FI system. The organic fraction was determined as the difference between total and inorganic Hg. Sample preparation, reagent consumption and parameters that can influence the FI-CVAFS performance were also evaluated. The limit of detection for this method is 3.7 ng g^?1 for total Hg and 4.3 ng g^?1 for inorganic Hg. The relative standard deviation for a 1.0 µg L^?1 CH₃Hg standard solution (n = 20) was 1.1%, and 1.3% for a 1.0 µg L^–1 Hg²⁺ standard solution (n = 20). Accuracy was assessed by the analysis of Certified Reference Material (dogfish: DORM-2, NRCC). Recoveries of 99.1% for total Hg and 93.9% inorganic Hg were obtained. Mercury losses were not observed when sample solutions were re-analysed after a seven day period of storage at 4°C.     

A simple route to derivatives of benzo[j]fluoranthene

3,6,8,11-Tetramethoxybenzo[j]fluoranthene can be made from 1,6-dimethoxynaphthalene in a one-pot ferric chloride oxidation/methanol reduction procedure. The reaction is tolerant of the presence of substituents in the 7-position of the naphthalene nucleus and provides a quick and easy route to these particular benzo[j]fluoranthenes. The reactions presumably proceed through initial formation of a bond between the 4-positions of two naphthalene molecules followed by closure of the five-membered ring. Indeed in one case some 4,4′-binaphthyl was isolated from the reaction mixture and it was generally found that better yields of the benzo[j]fluoranthrenes were obtained starting from the 4,4′-binaphthyl rather than by using the naphthalene as the starting material. In an analogous manner to the ring-closure of the 4,4′-binaphthyls, starting from a hexakisalkoxyphenylnaphthalene, a hexakisalkoxyfluoranthene could be obtained.