Drastic change of rheological behaviour of Precipitated Calcium Carbonate (PCC) formulations induced by water sorption onto mineral filler surface

The water sorption properties of Precipitated Calcium Carbonate (PCC) formulations have been studied in relation to the rheological behaviour. Uncoated mineral fillers (median diameter 0.85 μm) have been dispersed in an organic liquid used as plasticizer, a dioctylphthalate (DOP), at a concentration of 25% by weight (volume fraction of about 11%). Water sorption isotherms onto PCC in air and in the organic matrix have been constructed. Measurement of water concentration in the DOP permits a complete evaluation of water exchanges at the inorganic (mineral)/organic (plasticizer) interface. Evolutions of yield stress, storage modulus and loss modulus have been determined as functions of the water activity in the system. A drastic change of rheological properties has been observed for water activities above 0.3.     

LaI3.6C11H12ON2的合成和表征

用溶解度等温法研究了LaI3-C11H12ON2(安替比林)-H2O三元体系在0℃时的相平衡,体系中有组成为LaI3.6C11H12ON2的二元复合物生成。本文还确定了该复合物的制备条件,测定了它的一些性质,并对其结构作了初步分析。     

Sorption characteristics of water,oil and diesel in cellulose nanofiber reinforced corn starch resin/ramie fabric composites

Nowadays, utilisation of biodegradable materials has become necessary in order to maintain global environmental and ecological balance. Fully biodegradable nano 'Green' textile composites have been prepared from cellulose nanofibers reinforced corn starch resin and ramie fabric. Nanofibers having dimensions of approximately 1 μm long and 20–30 nm in diameter are used in the study. The nanofibers were incorporated in corn starch resin via ball mill mixing using ceramic balls. Textile composites were fabricated by pasting the reinforced resin onto the ramie fabric and by hot compression molding technique. Interactions at the fiber–matrix interface and the compatibility between cellulose and corn starch resin molecules will affect the properties of the system. The well dispersed cellulose nanofibers contribute higher interfacial area and good fiber networking within the matrix resin. This will lead to better barrier properties. Sorption characteristics of water, oil and diesel in the textile composites were analysed and the influence of nano fibers and macro fibers on the transport phenomena was investigated. The kinetics of sorption-diffusion process was investigated. Kinetic parameters such as n, k, diffusion coefficient, permeability, solubility parameter, % swelling index, etc., were analysed. The presence of cellulose nanofibers influences the sorption mechanism. The water sorption mechanism in the nanocomposites was found to exhibit slight deviation from Fickian mode. Structure–property relationships of the nanocomposites were evaluated.     

MeOH-H~2O-NaOAc体系(278.2~318.2K)的电导研究

本文测定了278.2~318.2K间的五个温度下七种浓度的NaOAc分别在10, 20,30, 40, 50, 60, 70, 80, 90及100%MeOH-H~2O体系中的摩尔电导Λ, 并应用FOS,Pitts, L-W, F-78等四个电导方程对实验数据进行了拟合处理, 得到了三个拟合参数Λ~O, K~Λ及R(或α)。最后, 对四个方程与实验的吻合程度, 温度、溶剂组成等对Λ~O、K~Λ的影响规律及溶质-溶剂相互作用进行了讨论。     

Structural and photocatalytic properties of the new solid photocatalyst In2BiTaO7

In₂BiTaO₇ was synthesized using the solid-state reaction method and its photocatalytic properties were investigated. The results of powder X-ray diffraction (XRD) indicated that the compound crystallizes in the pyrochlore-type structure, cubic system with space group Fd-3m. The lattice parameter is 10.6972(1) ?. In addition, the compound shows strong optical absorption in the visible region (λ > 420 nm) and the band gap of In₂BiTaO₇ was estimated to be about 2.47 eV. For the photocatalytic reaction, H₂ or O₂ evolution was observed from CH₃OH/H₂O or AgNO₃ solution respectively with In₂BiTaO₇ as the photocatalyst under visible light irradiation, indicating that In₂BiTaO₇ is responsive to visible light for splitting water. Furthermore, the catalyst remained photoactive in the wavelength range up to 510 nm. Photocatalytic degradation of methylene blue (MB) dye over the compound was further investigated under visible light irradiation. The results showed that complete removal of aqueous MB could be achieved after irradiation for 135 min over In₂BiTaO₇. Furthermore, under visible light irradiation In₂BiTaO₇ showed markedly higher catalytic activity compared to P-25 for MB photocatalytic degradation.     

纳米结构TiO2／SiO2的逐层自组装

采用逐层自组装方法在二氧化硅球表面交替组装了十二烷基硫酸钠单分子膜和 二氧化钛纳米粒子膜，该复合多层膜经高温假烧后得到了核壳型纳米结构二氧化钛 ／二氧化硅复合颗粒．利用XRD，SEM，X射线能谱等对复合颗粒进行了表征．结果 表明：二氧化肽在复合颗粒表面排列紧密、均匀，粒径在50nm左右，为锐钛矿型结 构．复合颗粒中二氧化肽的含量随组装层数的增加而均匀增加．     

NaCl在CH~3OH-H~2O混合溶剂中活度系数的测定(298.15K)

用电动势法测定了298.15K时,由Na^+和Cl^-离子选择电极组成的电池在NaCl-CH~3OH-H~2O混合体系中的电动势,用扩展的Debye-huckel方程和Pitzer方程关联不同溶剂组成下电动势的实验值,得到电池的标准电动势能和NaCl 在混合溶剂中的活度系数.将Pitzer-Simonson方程应用于含离子缔合体系.求出NaCl 在混合溶剂中的缔合常数,结果表明NaCl在甲醇含量为60%时,可能已有离子对生成     

四元体系Li^+,K^+,Mg^2^+/SO~4^2^——H~2O25℃相关系和溶液物化性质的研究

用等温溶解平衡法研究了四元体系Li^+,K^+,Mg^2^+/SO~4^2^--H~2O 25℃溶解度,测定了饱和溶液的密度,粘度,折光率,pH和电导率等物化性质. 四元体系相图由六条溶解度分枝线和五个结晶区构成,分别对应于原始组分和复盐Li~2SO~4·K~2SO~4,K~2SO~4·MgSO~4·6H~2O,没有发现新的复盐或固溶体, 也没有发生原始组分的脱水作用,用现代电解质溶液理论-Pitzer模型校验该体系的溶解度测定值, 结果令人满意     

铬天青S的液/液界面离子转移过程

本文研究了酸性染料显色剂铬天青S的液/液界面离子转移行为, 用循环伏安法和电流扫描计时电位法研究了铬天青S在水/硝基苯和水/1,2-二氯乙烷两种界面上的离子转移过程, 根据铬在青S在溶液中的离解平衡和电化学性质, 讨论了界面离子转移机理,研究了基础电解质和溶剂对铬天青S转移性能的影响, 在Britton-Robinson缓冲溶液中测得半波电位PH曲线与理论公式相一致, 由本法所得离解常数与文献值接近, 计算了转移离子的标准转移电位和标准吉布斯转移能。     

在DMSO-H~2O体系中β-环糊精催化酯水解加速程度误差问题的研究

由于β-环糊精(β-CD)对苯酚酯水解反应的催化机理与胰凝乳蛋白酶的作用机理十分相似,因此以β-CD作为模拟酶的动力学研究已经成为当前该化学领域中的一个重要课题.Breslow等报道,β-CD对2-二茂铁丙烯酸对硝基苯酚酯(1)的酰基转移反应或水解反应的催化加速程度K_c/K_(un)(k_c与k_(un)分别表示在OH~-离子浓度恒定的条件下β-CD存在及不存在时底物水解反应的速率常数)高达3.6×10~5,达到了典型的酶催化反应的数量级,因而引起了人们的广泛注意.