高比表面积窄孔分布氧化铝的制备研究 Ⅱ.加硅的影响

 采用pH摆动法，以硫酸铝为铝源，以氢氧化钠为碱沉淀剂，考察了添加SiO2对沉淀氧化铝物性的影响．通过孔结构分析、粒度测定和电镜观察等证实，加入少量SiO2可使沉淀粒子分散、变小，颗粒相对均匀，从而提高了氧化铝的比表面积和孔集中的程度．当加入2．5％的SiO时，pH仅摆动2次，即可使氧化铝粉体的孔体积高达1．2ml／g，比表面积达380m2／g．这类氧化铝的孔结构适宜，粒子小，易直接成型为孔径集中和耐压强度好的载体，故用于重油高压加氢脱氮反应具有较好的性能．沉淀时酸侧pH值降低，尽管沉淀氧化铝的孔径向较小的方面集中，但此时沉淀粒子呈紧密堆积，颗粒变大，比表面积下降，氧化铝沉淀粒子的结构发生改变．不同结构的氧化铝表现出不同的催化活性．     

Liquid-liquid microbatch extraction system for rapid mutual separation of fission products

The liquid-liquid microbatch extraction system (LMES) was developed for rapid separation of short-lived metal ions. The equipment is composed of three simple extraction cells for phase mixing, phase separation, and collection of a solvent. Metal separation can be completed in a single operation, lasting only a minute, from solvent extraction to preparation for gamma-ray spectrometry. As a demonstration of the rapid operation of the LMES, fission products were each separated into several categories after three stages of operation. The extractability in the LMES was comparable to that of traditional methods, and the developed method was feasible for rapid separation.     

钨—镍—铁系重合金中粘结相的定量测定

通过对９３Ｗ－Ｎｉ－Ｆｅ－Ｃｏ（Ｍｎ）合金中粘结相和钨颗粒化学及电化学性质的研究，提出了一种定量提取Ｗ－Ｎｉ－Ｆｅ系重合金中粘结相的电解液，建立了定量测定其粘结相和钨颗粒组成及含量的方法。     

Co-CeO2/SiO2催化剂上的费-托反应性能

 考察了反应条件对Co－CeO2／SiO2催化剂上费－托合成反应性能的影响，并对催化剂进行了1000h稳定性和再生性能实验．结果表明，添加铈助剂后，催化剂具有良好的稳定性和再生性能，整个过程中CO转化率为89．7％，C5＋烃类（主要组成为C10～C20直链烃）选择性为81．0％，链增长几率为0．90．催化剂的活性表面被反应产物蜡覆盖时，阻碍了反应物与活性中心的结合，是导致催化剂活性降低的主要原因．     

Adsorption and characteristics of base-treated pillared clays

The effect of base treatment on the cation exchange capacity (CEC) of pillared clays and their adsorption isotherms for Cu²⁺, Cr³⁺ and Pb²⁺ have been investigated. Results indicate that although the CEC of pillared clays are only about 15% of that of the parent clays, a large fraction of the native clays CEC may be recovered by treatment with base. The fraction of the CEC recovered depends upon the base strength, its concentration, and the temperature. Contrary to previous suggestions the mechanism of recovery is related to the destruction of pillars which is accompanied by the loss of surface area. It is possible under conditions specified to prepare these base treated pillared clays as a new class of useful, regenerable adsorbent for heavy metal adsorption from aqueous solution.     

Silica gel ethyleneimine and its adsorption capacity for divalent Pb, Cd, and Hg

Activated silica gel was directly modified with a cyclic molecule, ethyleneimine, yielding a surface with various nitrogen basic centers, ≡Sil–O(CH₂CH₂NH)_nCH₂CH₂NH₂. Infrared spectroscopy, ¹³C NMR, thermal, and elemental analyses confirmed the covalent attachment of the organic species onto the silica matrix. The purpose of this paper is to describe the interaction involving the grafted species on silica surface with the divalent heavy cations, Pb(II), Cd(II), and Hg(II), from aqueous solutions at room temperature. The process of metal extraction was followed by the batch method and the order of the maximum extraction capacities found was: 1.27 ± 0.04, 1.02 ± 0.02, and 0.98 ± 0.01 mmol g⁻¹ for Pb(II), Cd(II), and Hg(II) chlorides, respectively. These interactions were followed by calorimetric titration. The enthalpies of these processes are: −3.05 ± 0.02, −1.09 ± 0.01, and −9.88 ± 0.03 kJ mol⁻¹ for Pb(II), Cd(II), and Hg(II), respectively. The standard molar Gibbs free energies are in agreement with the spontaneity of the proposed reactions between cation and basic center.     

Generation of the first representatives of the Schrock complexes of heavy carbene analogs

The reaction of Cp*₂V with 7-sila(germa) norbornadiene derivatives generated the first representatives of Schrock complexes of heavy carbene analogs with transition metals. Decamethylvanadocene Cp*₂V can be used as a paramagnetic trap for short-lived dimethylgermylene.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 792–795, March, 2005.     

污染土壤重金属稳定化修复的综合性实验

添加不同种类改良剂对污染农田土壤进行有毒重金属的稳定化修复,内容包括土壤样品制备与培养、pH测定、重金属离子总浓度及有效态浓度测定。首先,学生需要在实验过程中熟练掌握电子天平、pH计、微波消解仪和电感耦合等离子体质谱的操作规程。其次,学生能够在课后利用固化率公式处理数据和评价不同改良剂对重金属的稳定化修复效果,并进行机理解析。本实验不仅可以加强学生对相关专业理论知识的理解和精密化学仪器的使用,还能够培养学生综合运用所学专业知识解决实际应用问题的能力,并进一步激发学生探索化学前沿新知,从而达到拓展创新的培养目标。     

火焰原子吸收分光光度法测大沂河水体的重金属含量

采用火焰原子吸收分光光度法测定了山东省曲阜市大沂河水体的重金属铜、铅、镉、锌含量。结果表明,大沂河水体中铜、铅、镉、锌的最高含量分别为0.018,0.230,0.176,0.490mg/L,其中铅和镉的含量超过国家Ⅴ类水标准。     

Ab initio studies of methylenecarbene and isoelectronic species

Optimum equilibrium geometries, energetics, harmonic vibrational frequencies, and infared intensities within the double harmonic approximation are computed for methylenecarbene, CCH₂, and isoelectronic species involving silicon and germanium at both the SCF level of theory and the level of second-order perturbation theory using a 6-311G(2df, 2p) basis set or its equivalent. Optimum equilibrium geometries and energetics are also computed at both levels of theory using a smaller 6-311G(d, p) basis set or its equivalent. This investigation of these species is the first to include all of the systems with germanium. In addition, this present work is the first study to includef-type polarization functions in a systematic investigation of the molecular structure and properties of all the molecules in the series. Acetylenic structures are also computed for energy comparisons. Of all the linear isomers, only acetylene is found to be a minimum on the potential energy surface. However, all of the C_2v structures are found to be local minima. Both the C_2v and linear structures will serve as a basis for future work involving mapping the entire hyperenergy surfaces of all of the molecular systems in the series.