甲醛与乙腈相互作用的理论研究

在HF/ 6 311G(d ,p)、MP2 / 6 311G(d ,p)和B3LYP/ 6 311G(d ,p)水平上 ,对H2 CO和CH3 CN以及设计的 4种结构H2 CO…CH3 CN复合物等进行几何全优化和振动频率计算 ,排除振动频率为负值的非局域极小点结构 ,并对稳定的环状构型复合物结合能进行基组重叠误差校正和零点振动能校正 .分子间相互作用的能量分解分析显示 ,静电能在H2 CO…CH3 CN相互作用能量中占主导地位 ,电荷转移能居第二位 .     

回填材料膨润土对放射性气体滞留能力模拟研究

利用各种分析手段对膨润土的物理特性进行了表征 .X射线衍射分析表明钠基膨润土呈典型的六方晶胞 ,晶胞参数是 :a轴 4 .913,c轴 5 .4 0 5 ;差热分析曲线在低温区和高温区有明显的吸热峰出现 ;元素分析钠、钾离子的含量大于钙、镁离子的含量 ,在性能上表现为钠质膨润土具有较强的离子交换能力 ;显微分析表明其表面呈皱隙状 ,测定比表面积高达 2 4 .5 2m2 /g;吸水率测定表明膨胀率大 ,说明它具有密封功能 ,可有效阻滞地下水的渗入 .利用SF6示踪技术 ,通过采集不同时间段取样池样品 ,分析样品中示踪气体浓度 ,绘制取样池示踪气体浓度随时间的变化关系曲线 ,根据费克扩散定律计算扩散系数 .实验结果表明 ,随着压实膨润土密度的增大 ,示踪气体扩散系数迅速减小 ,当密度大于 1.8g/cm3 时 ,扩散系数降至 10 -9m2 /s.研究结果表明 ,膨润土性能优化是通过在膨润土中添加适量的活性炭 ,可明显改善其对气体的阻滞能力 ;增加其对放射性气体滞留能力 ;添加少量的石英砂增加其机械性能、导热性和减少蠕变性 ,将引起对气体阻滞能力的下降 .综合考虑 ,在膨润土中各添加 5 %活性炭和石英砂 ,既对气体具有较好的滞留能力 ,又具有较好的工程特性 .     

十四烷基三甲基溴化铵对膨润土改性合成及其表征

用阳离子表面活性剂十四烷基三甲基溴化铵(C17H38NBr)对膨润土进行插层改性制备.配制浓度为2.35%十四烷基三甲基溴化铵溶液备用.在碘量瓶中称取3.04g膨润土,加入30mL超纯水、10mL十四烷基三甲基溴化铵溶液,制成土浆,放入微波炉中反应1min.产物经抽滤、洗涤、烘干、研磨,做FT-IR和DSC-TG分析.DSC曲线在500℃时有一明显的放热峰;TG曲线显示改性土的失重率有明显的增大.有机改性膨润土中确实含有大量有机物,改性成功.     

NBR/ORGANOMODIFIED BENTONITE INTERCALATED HYBRIDS AND THEIR EFFECTS ON THE TOUGHNESS OF PVC

Hybrids of intercalative nitrile-butadiene rubber/organomodified bentonite (NBR/OMB) were prepared by thelatex intercalation technique. Investigation of their mechanical properties and the microstructore of NBR/OMB showed thatthe organomodified bentonite is an effective toughener for NBR. Transmission electronic microscopy (TEM) and X-rnydiffraction (XRD) tests showed that the NBR macromolecule could be intercalated into the galleries of bentonite.Incorporation of NBR/OMB hybrids as tougheners into poly(vinyl chloride) (PVC) results in a substantial increase in theimpact strength of PVC, but little decrease in its tensile strength and flexural strength, compared to the unmodified PVC.     

杂多酸的固载化─关于制备负载型酸催化剂的一般原理

杂多酸同时具有酸和氧化－还原的催化特性，有着很广泛的应用前景．这类化合物在一系列精细合成中取代硫酸作为催化剂以满足环保的要求，显示出了很大的潜力．杂多酸固载化后，不仅能在液相氧化和酸催化反应中把催化剂从反应介质中很方便地分离出来，而且还为这类均相催化反应的多相化，甚至利用催化蒸馏新工艺等创造了应有的条件，可以使生产工艺大大简化，获得更广泛的应用．本文以很好表征过的多种孔性材料，包括氧化物，如Ａｌ_２Ｏ_３、ＳｉＯ_２、ＴｉＯ_２、硅藻土、膨润土和来源不同的活性炭为载体，考察了负载杂多酸催化剂的催化活性．在大量前期工作的基础上，通过总结载体对固载杂多酸催化活性的影响等，探讨载体的内在性质在杂多酸固载、吸附和催化反应中的作用本质，为由吸附法制备各种负载型固体酸催化剂在液相中的应用提供可资参考的模型．     

Drying dissipative structures of the aqueous suspensions of monodisperse bentonite particles

Macroscopic and microscopic dissipative structural patterns formed in the course of drying the fractionated and monodisperse bentonite particles (plate-like in their shape) in aqueous deionized suspension and in the presence of NaCl have been studied on a cover glass. The patterns coexisted with the broad ring of the hill accumulated with the particles and with the round hills are formed around the outside edges of the film and in the center, respectively, in the macroscopic scale. By the addition of NaCl the pattern shifts from the broad ring to the round hill in the center. The spoke-like cracks, which have been observed for the suspensions of the spherical particles so often hitherto, are not observed at all for the bentonite suspensions. The characteristic convection flow of the particles and the interactions among the particles and substrate are important for the macroscopic pattern formation. Wrinkled, branch-like and/or star-like fractal patterns are observed in the microscopic scale. These patterns are determined mainly by the electrostatic and polar interactions between the particles and/or between the particle and the substrate in the course of drying.     

有机膨润土的吸附性能研究

有机膨润土处理水中有机物的研究已有报道［1－4］，但尚无就改性所用的表面活性剂对有机膨润土吸附性能的影响及规律的系统研究，对有机膨润土与不同有机物间作用机理的报道也甚少［1］．本文用3种不同的阳离子表面活性剂改性膨润土，并从等温吸附线的特征和有机物的辛醇－水分配系数较系统地研究了有机膨润上对几种有机物的吸附性能和作用机理．1实验部分1．1材料原士为钠基膨润土，经测定其阳离子交换容量为7464meg／100g土；澳化十六烷基王甲铰（CTMAB）为分析纯，溪化十二烷基三甲铰（DTMAB，95％），演化十八烷基三甲按（OTMAB…     

甲壳素-壳聚糖对皂土悬浮液的絮凝

研究了三种摩尔质量大体相同而脱乙酰度分别为93%、78%和62%的甲壳素-壳聚糖在pH=3～6范围内对皂土悬浮液的絮凝性质, 并与非离子型絮凝剂聚丙烯酰胺作了比较, 证明含自由氨基的甲壳素-壳聚糖在酸性溶液中形成阳离子聚电解质后. 对带负电的皂土悬浮颗粒有很好的絮凝能力. 通过对上述三种聚合物的絮凝能力、在皂土颗粒表面的吸附量等测定, 认为絮凝中桥连机制起了主导作用, 但聚合物所带正电荷则有利于被皂土颗粒所吸附, 电中和还降低了颗粒间的静电排斥, 这都对桥连絮凝起了促进作用. 聚丙烯酰胺分子在水中不带电, 故当介质pH升高使皂土颗粒双电层变厚时, 絮凝能力迅速下降.     

膨润土碱熔活化合成4A分子筛的研究

以天然膨润土为原料,采用高温碱熔水热法合成4A分子筛。探讨了活化温度、SiO2/Al2O3、Na2O/SiO2、H2O/Na2O等工艺条件对4A分子筛结构与性能的影响。结果表明,最佳的活化温度为600℃;物料经此温度活化后,调节组成为SiO2/Al2O3=1.5、Na2O/SiO2=3与H2O/Na2O=50,于90℃反应6小时可以得到质量较好的4A分子筛,其产品的晶形规整,晶粒均小于2μm,钙离子交换容量可达到314mg CaCO3/g。     

FTIR analysis of bentonite in moulding sands

Bentonite is used in a wide range of applications. One of them is the foundry industry. The aim of this study was to investigate modification of moulding sands by dust which is generated during foundry process. Recycling of this dust is very important from ecological point of view. The samples of moulding sands were examined by Fourier Transform Infrared spectroscopy (FTIR). Analysis of the bands due to the Si–O stretching vibrations allows to reveal the changes of active bentonite and silica sand, i.e. the main components of the moulding sands. FTIR results are compared with technological properties of the materials studied. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) methods have been used as the complementary measurement.