Co2+、Zn2+、Cd2+的阴离子交换色谱法分离研究

本文对钴与锌、镉等金属离子的阴离子交换色谱法分离进行了研究．采用201×7型阴离子交换树脂经氧化铵溶液饱和后,在pH＝4．0时,使钴与其它金属离子分离,然后分别用0．02mol／L的盐酸溶液及蒸馏水将锌、镉等金属离子从阴离子交换树脂上洗脱．此法分离效果好,操作简单方便．     

Cl2+2HI=2HCl+I2反应机理的理论研究

分别在MP2/3-21G**、CCSD(T)/3-21G**//MP2/3-21G**和B3LYP/3-21G**3种水平上, 计算研究了气相反应Cl₂+2HI=2HCl+I₂的机理, 求得一系列四中心和三中心的过渡态. 通过比较六种反应通道的活化能大小, 得到了相同的结论：双分子基元反应Cl₂+HIHCl+ICl和ICl+HII₂+HCl的最小活化能小于Cl₂、HI和ICl的解离能, 从理论上证明了反应Cl₂+2HI=2HCl+I₂将优先以分子与分子作用形式分两步完成. 用内禀反应坐标(IRC)验证了MP2/3-21G**方法计算得到的过渡态.     

Cl_2+2HBr=2HCl+ Br_2反应的机理和应用

用密度泛函理论（ＤＦＴ）Ｂ３ＬＹＰ方法,取６－３１１ Ｇ**基组,细致研究了反应Ｃｌ２＋ ２ＨＢｒ＝ 2ＨＣｌ＋ Ｂｒ２的机理,求得一系列四中心和三中心过渡态．双分子基元反应 Ｃｌ２＋ ＨＢｒ→ ＨＣｌ＋ ＢｒＣｌ和 ＢｒＣｌ＋ ＨＢｒ → Ｂｒ２＋ ＨＣｌ的活化能（１３８．９６和 １４７．２４ ｋＪ· ｍｏｌ－１）小 于Ｃｌ-２,ＨＢｒ和ＢｒＣｌ的解离能,从理论上证明了标题反应将优先以分子与分子作用形式 完成．将其应用于从ＨＢｒ中回收溴,以Ｃｌ２直接与ＨＢｒ气体反应,生成的含溴混合气体, 经冷凝并以四氯化碳吸收分离得到液溴和盐酸;溴的回收率大于９６％,其含氟量小于 ３．０％．提供了运用基础理论解决生产中难题的成功例证．     

Ga2S3∶Eu2+和SrGa2+xS4+y∶Eu2+系列荧光粉的发光性能研究

采用高温固相法合成了Ga2S3∶Eu2+和SrGa2S4∶Eu2+系列荧光粉. 发现Ga2S3∶Eu2+的发射峰位于570 nm附近, SrGa2S4∶Eu2+的发射峰位于535 nm附近. 同时进一步探讨了SrGa2+xS4+y∶Eu2+体系中, 过量的Ga对发光的影响, 通过漫反射光谱和XRD谱确定过量的Ga是以Ga2S3的形式存在于SrGa2S4相中; 通过荧光光谱发现过量的Ga并不引起SrGa2S4∶Eu2+发射峰的位移, 而是增强其在400～520 nm处激发峰的强度, 从而增强Eu2+在535 nm处的发光强度.     

红麻纤维改性及其对Ni2+、Cu2+、Cd2+的吸附性研究

向天然纤维链上吸附性功能基制得的改性纤维不仅对金属离子的吸附容量,而且能应用于废水处理和环境保护等诸多领域。如果将大量废弃残麻接枝改性为对应吸附材料,并用于治理废水污染,则更具“双废开发,双废利用”价值。我们以信阳盛产的红麻纤维为母体,选取4-(2-吡啶偶氮)间苯二酚为功能基,在相关工作基础上,制备了4-(2-吡啶偶氮)间苯二酚基红麻纤维。同时,测试红麻纤维对Ni^2 、Cu^2 、Cd^2 的吸附性能,探讨了吸附温度、时间及介质酸度等因素对吸附的影响。     

HNCO+OH-→NH2+CO2反应理论研究

用从头算UHF/6-31G基组研究了异氰酸和羟基生成氨基和二氧化碳即HNCO+OH→NH2+CO2的反应机理.优化得到了反应途径上的过渡态和中间体,并通过振动分析对过渡态和中间体进行了确认.在UMP4/6-31G水平上计算了它们的能量,同时对零点能进行了较正.计算结果表明:此反应是多步反应,先后通过3个过渡态(TS1,TS2,TS3),2个内旋转位垒(PSI,TSII),4个中间体(IM1,IM2,IM3,IM4),其中,IM3→TS2这一步为整个反应的决速步骤,速控步的活化能为202.388lJ/mol.与异氰酸和羟基作用的另一反应通道(即HNCO+OH→H2O+NCO)的活化能(69.038kJ/mol)比较,可看出所研究反应通道为次要反应通道,这与实验结果是一致的.     

改性磁性壳聚糖微球对Cu2+、Cd2+和Ni2+的吸附性能

Fe3O4/ chitosan magnetic microspheres of 50 to 80 滋m were prepared using the inverse phase emulsion dispersion and chemical crosslinking technology, and then modified with ethylenediamine for use in the adsorption of heavy metal ions. The adsorption properties of the modified Fe3O4/chitosan toward Cu2+, Cd2+ and Ni2+ were investigated. It was found that the adsorption capacities of Cu2+ and Ni2+ increased with pH, and a maximum adsorption for Cd2+ occurred at pH=3. The saturated adsorption capacities calculated by Langmuir isotherms were 54.3 mg·g-1 for Cu2+, 20.4 mg·g-1 for Cd2+, and 12.4 mg·g-1 for Ni2+, respectively. The adsorption kinetics were well described by pseudo-second-order equation models. The experimental results showed that the Fe3O4/chitosan modified with ethylenediamine presented higher adsorption selectivity for Cu2+ than for Cd2+ and Ni2+ in all studied pH ranges.     

过渡金属催化[2 + 2 + 2]环加成反应合成吡啶衍生物

环加成反应可以一步同时构建多个化学键,是目前国内外研究最为活跃的领域之一。相比于传统方法,过渡金属催化的[2+2+2]环加成反应是合成吡啶衍生物的有效手段。本文从反应机理、非手性吡啶化合物合成和手性吡啶化合物合成三个方面阐述了近年来吡啶衍生物的研究情况,涉及Co、Rh、Ru、Fe、Ni、Ti等金属催化体系。     

2-乙酰吡啶吖嗪及其与Co2+、Ni2+、Fe3+、Zn2+配合物的合成和生物活性

过渡金属;超氧离子;白血病;肺癌;2-乙酰吡啶吖嗪及其与Co2+、Ni2+、Fe3+、Zn2+配合物的合成和生物活性     

改性皮革胶原纤维对水体中Cd2+、Cr3+、Pb2+、Ni2+、Co2+等痕量重金属离子的富集与测定

利用改性皮革胶原纤维作为水体中重金属离子的富集材料,研究了该材料对水体中Cd^2＋、Cr^3＋、Pb^2＋、Ni^2＋、Co^2＋等重金属离子的分离富集能力。实验表明,在pH4～7的酸性和中性的条件下,该材料对重金属离子的富集量最大。其中,Cr^3＋在pH4～5时富集率达到100％;Co^2＋、Ni^2＋在pH6～7时富集率达到100％左右;Cd^2＋和Pb^2＋在pH8～9时富集率达到100％左右;在混和溶液中和存在络合配位体时,可以通过控制待测液的酸度对水体中的重金属离子进行选择性吸附。通过样品的分析,可以利用改性皮革胶原纤维作为测定水体中的重金属离子的吸附剂,对水体中的重金属离子进行分析测定。     

水热重结晶法制备四方相纳米Ba0.9Ca0.1TiO3晶体的研究

采用水热重结晶法对低温液相法制备的Ba_0.9Ca_0.1TiO₃(B_0.9C_0.1T)浆料进行220 ℃, 3 h的水热处理, 成功制备了四方相B_0.9C_0.1T纳米粉体. 并对水热重结晶和未水热处理的两种粉体进行了TEM, XRD, Raman, FT-IR, TG和介电性能的表征. 研究表明, 经水热重结晶后的B_0.9C_0.1T粉体体系发生从顺电立方相向铁电四方相的转变, 羟基缺陷以及CO₃^2－杂质显著减少, 粉体形貌由外边缘毛躁的球形转变为四边形. 并发现羟基缺陷的减少是影响体系相转变的关键因素.     

锰掺杂Ba0.6Sr0．4TiO3-MgTiO3复相陶瓷的制备和介电性能

以分析纯的Ba(NO3)2、Sr(NO3)2、草酸和钛酸丁酯为原料,采用草酸盐共沉淀法制备了钛酸锶钡(Ba0.6Sr0.4tiO3,BST)纳米粉体.XRD和SEM分析结果表明,该方法制备出立方相的Ba0.6Sr0.4TiO3粉体,平均粒径小于100 nm,具有较高的烧结活性.用传统固相法制备了锰掺杂钛酸锶钡.钛酸镁(Ba0.6Sr0.4TiO3-MgTiO3,BST-MT)复相陶瓷,系统研究了掺杂0.1%-2.0%(x,摩尔分数,下同)锰对钛酸锶钡-钛酸镁复相陶瓷微观形貌和介电性能的影响机理.结果表明,当锰的掺杂量小于1.5%时,Mn作为受主掺杂取代占据钙钛矿ABO3的B位,因此导致居里点略微向高温偏移和相变扩散的发生,锰的掺杂导致晶格畸变,促进了晶粒生长,使晶界相比例下降,因此介电损耗随着锰掺杂量的增大而减小;当锰的掺杂量为1.5%时,介电损耗达到最小值,继续增大掺杂量,介电常数下降,介电损耗上升.     

锰掺杂Ba0.6Sr0.4TiO3-MgTiO3复相陶瓷的制备和介电性能

以分析纯的Ba(NO3)2、Sr(NO3)2、草酸和钛酸丁酯为原料, 采用草酸盐共沉淀法制备了钛酸锶钡（Ba0.6Sr0.4TiO3, BST）纳米粉体. XRD和SEM分析结果表明, 该方法制备出立方相的Ba0.6Sr0.4TiO3粉体, 平均粒径小于100 nm, 具有较高的烧结活性. 用传统固相法制备了锰掺杂钛酸锶钡-钛酸镁(Ba0.6Sr0.4TiO3-MgTiO3, BST-MT)复相陶瓷, 系统研究了掺杂0.1%-2.0%(x, 摩尔分数, 下同)锰对钛酸锶钡-钛酸镁复相陶瓷微观形貌和介电性能的影响机理. 结果表明, 当锰的掺杂量小于1.5%时, Mn作为受主掺杂取代占据钙钛矿ABO3的B位, 因此导致居里点略微向高温偏移和相变扩散的发生, 锰的掺杂导致晶格畸变, 促进了晶粒生长, 使晶界相比例下降, 因此介电损耗随着锰掺杂量的增大而减小; 当锰的掺杂量为1.5%时, 介电损耗达到最小值, 继续增大掺杂量, 介电常数下降, 介电损耗上升.     

Y2O3包覆LiCo1/3Ni1/3Mn1/3O2的电化学性能

通过在硝酸钇水溶液浸渍并焙烧的简单工艺, 在LiCo1/3Ni1/3Mn1/3O2材料表面包覆了一层Y2O3. 采用X射线衍射(XRD), 扫描电子显微镜(SEM), 透射电子显微镜(TEM), 循环伏安(CV)和恒流充放电对包覆和未包覆的LiCo1/3Ni1/3Mn1/3O2进行了测试分析. 结果表明, Y2O3包覆并没有改变LiCo1/3Ni1/3Mn1/3O2的晶体结构, 只存在于LiCo1/3Ni1/3Mn1/3O2的表面; 与未包覆的材料相比, Y2O3包覆后的材料在高电位下具有更好的容量保持率和放电容量. CV测试表明, 包覆层的存在有效抑制了材料层状结构的转变及电极与电解液的负反应.     

Nanofibers of barium strontium titanate (BST) by sol-gel processing and electrospinning

This paper describes the fabrication of barium strontium titanate (Ba0.6Sr0.4TiO3 or BST) nanofibers by electrospinning method using a solution that contained poly(vinylpyrrolidone) and a sol-gel solution of BST. The as-spun and calcined BST/PVP composite nanofibers were characterized by TG-DTA, X-ray diffraction, FT-IR, SEM and TEM, respectively. After calcination of the as-spun BST/PVP composite nanofibers at above 700 degrees C in air for 2 h, BST nanofibers of 188+/-25 nm in diameter having well-developed cubic-perovskite structure were successfully obtained. The crystal structure and morphology of the nanofibers were influenced by the calcination temperature. Calcination at below 700 degrees C resulted in amorphous phase whereas BST with second phase such as barium titanate were formed at above 700 degrees C. Diameters of the nanofibers decreased from 208+/-35 to 161+/-18 nm with increasing calcination temperature between 600 and 800 degrees C.     

Temperature dependency of element incorporation into European eel (Anguilla anguilla) otoliths

The present study experimentally tested the influence of water temperature on the inclusion of 15 elements into juvenile European eel (Anguilla anguilla) otoliths in freshwater. It should be investigated (1) if temperature effects on otolith Sr/Ca might impair the interpretation of migration studies and (2) if the elemental composition of otoliths can be used to reconstruct experienced temperature histories of eels. Therefore, eels were kept under full experimental conditions at three different water temperatures (14 °C, 19 °C and 24 °C) for 105 days. Thereafter, laser ablation inductively coupled mass spectrometry (LA-ICPMS) was conducted on the outer edge of their otoliths. Our analyses revealed significant temperature effects on otolith Na/Ca, Sr/Ca, Mg/Ca, Mn/Ca, Ba/Ca, Zr/Ca and Y/Ca ratios. Variations of Sr/Ca caused by temperature were far below those used to detect eel movements between waters of different salinities and will therefore not affect the interpretation of migration studies. Elemental fingerprints of Sr/Ca, Mg/Ca, Mn/Ca and Ba/Ca ratios resulted in clearly separated groups according to temperature treatments, indicating that changes in water temperature might lead to characteristic changes in otolith element composition. However, the successful application of elemental fingerprints to reconstruct moderate changes of water temperature seems doubtful because the influence of somatic growth on otolith microchemistry still remains unclear, and temperature-induced variations could be overlaid by changes of water element concentrations during growth periods. Nevertheless, our results contribute to the completion of knowledge about factors influencing element incorporation and help to explain variations in element composition of fish otoliths.     

Tl2Ba2Ca2Cu3O10的化学键性质和同质异能位移研究

Tl2Ba2Ca2Cu3O10 was reported to be a superconductor with a highest transition temperature of 125 K among the homologous series of Tl2Ba2Can-1CunO2n+4. The direct information on the Cu ion site at the atomic level is important for elucidating the superconductivity mechanism. The local bond properties of Tl2Ba2Ca2Cu3O10 were studied using the average band-gap model. The calculated results show that the covalency of Cu(1)-O bond is 0.561, and the average covalency of Cu(2)-O is 0.296. M(o)ssbauer isomer shifts of 57Fe in Tl2Ba2Ca2Cu3O10 were calculated using the chemical surrounding factor, defined by covalency and electronic polarizability. It is verified that for lower doping, Fe substitute the Cu at the Cu (1) site in forms of Fe3+ and Fe4+; for higher doping, Fe3+ and Fe4+ ion occupies Cu(1) and Cu(2) site respectively.The studies show that the determination of the correspondence between spectrum components and actual copper sites occupied by M(o)ssbauer nucleus was made easier with the aid of the calculation results of the chemical bond parameters.     

CaxLa1-xMnAl11O19 六铝酸盐催化剂上甲烷的催化燃烧

以共沉淀法制备了CaxLa1-xMnAl11O19系列六铝酸盐催化剂,考察了Ca2 部分取代La3 对LaMnAl11O19六铝酸盐的甲烷催化燃烧活性和稳定性的影响以及活性与物理化学性能的关系,用X射线衍射、N2吸附、程序升温还原和透射电镜对其进行了表征.结果表明,当Ca2 加入量过高时,Ca2 不能进入到六铝酸盐骨架中,过量的Ca2 形成CaAl4O7杂相.当x=0.2时,催化剂活性最高,起燃温度为723 K,也提高了样品的热稳定性,1 373 K煅烧后比表面积为26.1 m2/g.Ca2 的加入使六铝酸盐晶粒变薄,这使材料的抗烧结性能增强,比表面积增大,同时Ca2 部分取代La3 使活性Mn3 的含量增加,这两方面的综合作用使得催化剂活性显著提高.对Sr2 ,Ca2 和K 部分取代La3 的六铝酸盐的比较实验结果表明,Ca2 部分取代La3 的样品具有最低的起燃温度.     

Mn/Ba/Al2O3催化剂的NOx氧化-储存和耐硫性能

采用分步等体积浸渍法制备了Mn/Ba/Al2O3催化剂, 并用XRD和TPD等方法进行表征. 考察了催化剂在不同温度下NOx氧化-储存特性和NOx脱附行为. 结果表明, Mn/Ba/Al2O3催化剂具有较高的催化NO氧化活性和较大的NOx储存容量. BaMnO3是主要的活性组分；Mn能够催化NO的氧化反应, 且具有一定的NOx储存能力; Ba是主要的储存组分, 将NOx以硝酸盐的形式储存; 硝酸盐在300～600 ℃分解, 释放出NOx. Mn/Ba/Al2O3催化剂在800 ℃老化6 h后, NO氧化活性和NOx储存能力稍有下降. 低含量的SO2对催化剂的NO氧化活性和NOx储存能力没有明显影响; 高含量的SO2使催化剂的NO氧化活性降低, NOx储存量减小, 最终导致催化剂失活.     

Asymmetric leakage in (Ba,Sr)TiO3 nanoparticle/parylene‐C composite capacitors

Nanoparticle polymer composite capacitors have been examined for some time as a route to high performance, printable capacitors. One approach to creating these composites is to use a particle film together with vapor deposited polymers, which can yield high performance, but also forms a structurally asymmetric device. The performance of a nanoparticle (Ba, Sr)TiO₃ (BST)/parylene‐C composite capacitor is compared to that of a nanoparticle BST capacitor without the polymer layer under both directions of bias. The composite device shows a five orders of magnitude improvement in the leakage current under positive bias of the bottom electrode relative to the pure‐particle device, and four orders of magnitude improvement when the top electrode is positively biased. The voltage tolerance of the device is also improved and asymmetric (44 V vs. 28 V in bottom and top positive bias, respectively). This study demonstrates the advantage of this class of composite device construction, but also shows that proper application of the device bias in this type of asymmetrical system can yield an additional benefit. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013