The effect of PbO content on the properties of modified lead titanate ceramic resonator

The effect of PbO content which varied from 72 to 87 mole% on the resonator properties of ceramics Pb_1-1-5xLa_xTiO₃ + 0.5 wt% MnO₂ (with x=0.12) has been examined. The mechanical quality factor Qm increases with the PbO content. On the other hand, in the deficient case of PbO, the dielectric constant E T3 3 and the temperature coefficient TCF₃ decrease; the mechanical quality factor Qm_t3 and the coupling factor k_t3 increase which make certain improvement on the ceramic resonators utilizing third harmonic thickness vibration when compared with stoichiometric PbO content (82 mole%).     

改性膨润土对废水中染料的吸附

简述了膨润土的基本结构,概括了膨润土的主要改性方法,即活化改性法和添加改性剂改性法;分析了改性方法的主要优点,总结了改性膨润土对废水中染料的吸附效果.结果表明,改性膨润土对染料的吸附效果较好,染料去除率最大可达99.7％.另外,探讨了改性膨润土的吸附机理、影响因素和吸附等温式,并展望了改性膨润土的应用前景.     

The influence of PbO modification on the kinetics of the 4PbO·PbSO4 lead-acid battery paste formation

The influence of PbO modification on the formation of 4PbO·PbSO₄ paste is determined by X-ray diffraction analysis and scanning electron microscopy. The paste was prepared from tetragonal PbO, orthorhombic PbO and several mixtures of both oxides at 80° C and a H₂SO₄/PbO ratio of 6 wt%.The reaction scheme of 4PbO·PbSO₄ formation depends on the PbO modification. When tetragonal PbO is used, 3PbO·PbSO₄·H₂O crystals are obtained first and then 4PbO·PbSO₄. If the initial oxide is orthorhombic PbO, PbSO₄, PbO·PbSO₄ and 3PbO·PbSO₄·H₂O are formed successively. When the correct ratio of 3PbO·PbSO₄·H₂O, orthorhombic PbO and tetragonal-PbO is achieved in the paste then 4PbO·PbSO₄ formation begins. This ratio is reached most quickly if tetragonal PbO is present at 30–60wt% in the initial mixture of both modifications.     

The effect of mineral composition on the interaction of strontium ions with geological formations

The surface reaction of strontium ions was studied on rock samples with a radioactive tracer method. The experimental distribution coefficient was calculated from the equilibrium adsorption yield. The distribution coefficient of montmorillonite, rectorite, illite, quartz and cristobalite was determined from the mineral composition and the distribution coefficient of samples with a linear model. On the basis of our linear model and the distribution coefficients of the mineral components, the equilibrium sorbed quantities of strontium ions (or other cations) on any rocks can be predicted when we determine the mineral composition (and the distribution coefficients of the minerals for the given cation). It is very advantageous because of the great variety of geological formations, a lot of experimental work can be neglected. The adsorption parameters make possible the prediction of the migration properties, too. This model can also be used for the design of a geological radioactive waste repository.     

膨润土合成有机膨润土的研究

本文以辽宁抚顺膨润土为原料,对有机膨润土的合成进行了研究,并对所得产品进行了XRD、SEM、IR和DAT／TG等表征。     

膨润土有机改性提高分散性的研究进展

介绍了国内对膨润土进行有机改性提高分散性的主要研究进展,包括季铵盐改性膨润土、氯铵盐改性膨润土、溴铵盐改性膨润土、酰胺改性膨润土、吡啶改性膨润土、硅烷改性膨润土、十二烷基磺酸钠改性膨润土等,对这些方法做了比较及评价,并对今后的研究方向提出建议。     

膨润土有机改性提高分散性的研究进展

介绍了国内对膨润土进行有机改性提高分散性的主要研究进展,包括季铵盐改性膨润土、氯铵盐改性膨润土、溴铵盐改性膨润土、酰胺改性膨润土、吡啶改性膨润土、硅烷改性膨润土、十二烷基磺酸钠改性膨润土等,对这些方法做了比较及评价,并对今后的研究方向提出建议。     

The breakdown of PbO2-Ti anodes

Lead dioxide-titanium electrodes have been tested as oxygen evolving anodes in 1 mol dm^–3 H₂SO₄, at high current densities. Three modes of failure, shedding, thinning and deactivation have been identified. The first two are the result of stresses produced during electrodeposition, compounded by the thermal effects of polarization. Some improvements in these aspects of performance have been made by manipulation of the plating conditions. Deactivation has been modelled by considering the diffusion of special sites from the bulk material. There is continuous redeposition of PbO₂ from the solution.     

一种新型二氧化铅电极的研制

用二氧化铅作为电极材料，研究了用铂为基体二氧化铅电极的研制，对在不同反应条件下电镀制成的电极进行了性能测试，并用XRD，XPS，SEM等分析手段进行了表征，得到了电极制作的最佳条件，此电极具有好的应用前景。     

The effect of double layer interaction on the drainage of thin liquid films

The drainage of thin liquid films of an aqueous solution containing anionic surfactant and inorganic electrolyte between platinum and a mercury pool electrode was examined by the capacitance method. The system consisted of either symmetrical or unsymmetrical potentials of diffuse double layers which were estimated by differential capacitance measurements. The results showed that the drainage of the liquid film initially took place quickly and then slowly attained an equilibrium thickness. This general tendency could be explained qualitatively by the theoretically calculated disjoining pressure but the equilibrium thickness of 7–13 nm was too small to be explained in terms of electrostatic repulsion and van der Waals attraction. Hence, it was supposed that other forces, such as steric hindrance, are acting to thicken the film in addition to the above mentioned disjoining pressure. The force acting on the film obtained from the Reynolds equation also indicates the presence of other forces which are acting to thin the film in addition to gravity.     

改性膨润土制备二氧化钛复合材料的光催化性能

以改性膨润土和四氯化钛为原料,采用水热法制备TiO2/膨润土柱撑复合材料,以甲基橙的光降解为研究重点,探讨了催化剂光降解过程,对催化反应机理进行了研究。结果显示,用各种改性膨润土合成的TiO2/膨润土柱撑复合材料层间距都有不同程度的增大;各TiO2/膨润土柱撑复合材料对甲基橙的光催化遵循一级动力学方程机理;催化剂经H2SO4和H2O2处理,可重复使用。     

The temperature effects on hydraulic conductivity of compacted bentonite

The hydraulic conductivities of water saturated Ca-bentonite with dry densities of 1.4, 1.6, and 1.8 Mg/m³ were measured within the temperature range of 20 to 80°C. The hydraulic conductivities of all the compacted bentonites are lower than 10⁻¹¹ m/s, and the relationship between the logarithm of the hydraulic conductivity and the bentonite dry density can be fitted to a straight line. The hydraulic conductivities of bentonites increase with increasing temperature, and the hydraulic conductivities at 80°C increase up to about three times those at 20°C. The measured values are in agreement with those predicted from the hydraulic conductivities at 20°C assuming that only fluid properties are changed with changing temperature. The change in viscosity of water with increasing temperature contributes greatly to the increase of hydraulic conductivity.     

金溪膨润土的流变性研究

对金溪膨润土的流变性进行了系统研究。结果表明:质量分数、剪切力、溶解温度、加热时间、pH值、冻融条件与时间等变化对金溪膨润土的粘度有较大影响。金溪膨润土溶液具有较高的粘度,当矿浆质量分数达到60%时,其粘度为542.8mPa·s,金溪膨润土溶液为"非牛顿流体",加热时间与温度对金溪膨润土粘度影响较大,金溪膨润土溶液在酸性和碱性条件下都较为稳定,冻融处理后金溪膨润土粘度大幅度下降。     

Determination of pore water composition during long term interaction of bentonite substrates with water media: Comparative study

Knowledge of pore water composition is crucial information in research of long-term stability of bentonite and is also crucial for any stability predictions based on geochemical modeling. This paper reports validation results of two frequently used extraction methods — centrifugation and leaching. Three types of bentonite materials were used in our study. The first one was the Czech raw bentonite from the Rokle deposit. The second type of bentonite was “Mock-Up-Cz”, which is a mixture of bentonite material from the Rokle deposit with finely ground quartz and graphite powder. The third type of material was the FEBEX bentonite obtained from the Cortijo de Archidona deposit. All the bentonite samples were placed into pressure vessels and interacted with natural water during a one-year experiment. Free water, obtained during these interactions, was used as a comparative pore water composition for both of the extraction methods. The high water content in saturated bentonite, reaching about 50 m%, allowed the use of both methods. Concentrations of Mg^2 +, Ca^2 +, K⁺ and Na⁺ in water were determined. Centrifugation could be generally considered as a more suitable method because of the smaller differences between free water composition and concentrations obtained from extracted pore water compared to the leaching method. However, actual differences will depend on the type of bentonite and on the composition of the water media. In some cases, the leaching method yields better results. Leaching usually leads to higher concentrations of alkali metals and lower concentrations of alkaline earth metals. This indicates that bentonite substrates are sensitive to the change of external conditions and quickly interact with the water media.     

改性皂土制备复合干燥剂的研究

皂土加入无水氯化钙、微晶纤维素和中性红试剂等,制备一种吸水率高、吸水时间长、以颜色变化为指标的复合型干燥剂。研究表明,皂土经过酸洗处理吸水性明显高于未酸洗的皂土,皂土和无水氯化钙、微晶纤维素的质量比为5∶3∶3时,吸水效果最优,48 h吸水率达103%。     

膨润土制备高效活性白土的研究

本文以安徽某地膨润土为原料,首先对其分级提纯,然后对影响活性白土质量的主要工艺条件进行较为系统的试验研究,成功地制备了脱色力大于２００,且脱色率,活性度超过国家化工行业规定的一等品标准的高效活性白土。     

Characterizing the effect of substrate surface roughness on particle-wall interaction with the airflow method

The effect of surface roughness on particle-wall interaction was studied by the airflow method. Five kinds of monodispersed spherical particles (D_p50 = 11-41 μm) and six test pieces with different surface roughness (Ra = 0.01-1.64 μm) were used in the experiments. The particles were dispersed on the test pieces to form a monolayer, and entrained in a rectangular air channel. The air velocity increased at a constant rate, and the entrained particles were detected with a laser dust monitor. Microscopic observations showed that particle entrainment occurred in discrete and intermittent events during experiment, thus a statistical parameter, i.e. the particle entrainment efficiency as a function of the air velocity, was defined for evaluating the particle-wall interaction force distribution. The experimental results showed that the air velocity for particle entrainment decreases with the increase of the surface roughness within submicron-scale and reaches a lower limit, while increases to some extent for micron-scale surface roughness. It was also found that the effect of the substrate surface roughness depends on the particle diameter.     

膨润土处理重金属离子废水的研究进展

概述了膨润土的基本结构和性质,阐述了膨润土处理重金属离子废水的研究进展,并指出了该技术存在的一些问题,对该技术的发展前景进行了展望.     

钼酸铵改性膨润土对屠宰废水处理的实验研究

以钼酸铵为改性剂,对天然膨润土进行无机改性,制得钼酸铵无机改性土用于屠宰废水的处理.实验结果表明:在投加膨润土质量浓度为15 g/L、pH=5、搅拌时间为10 min、离心时间10 min的条件下,COD去除率可达90%,达到了预期目标.