NiO_x/介孔杭锦2~#土的制备及其对苯羟基化光催化性能研究

以沉积沉淀法制备Ni Ox/介孔杭锦2#土催化剂,通过X射线粉末衍射,比表面积及孔结构分析,固体紫外可见漫反射等手段对催化剂进行了表征.以H2O2为氧化剂,在汞灯照射下,研究其对光催化苯直接羟基化反应的催化性能,并探讨了镍的负载量,光源等因素对苯直接氧化制苯酚反应的影响.结果表明,随着镍含量的增加,苯酚的选择性和产率先增大后减小.在优化的反应条件下,苯酚的选择性和产率分别为93%和为56%.     

浅谈重金属元素在土壤中的迁移及黏土矿物对其修复作用

重金属元素在土壤中的存在形式有多种,且迁移能力各不相同,而影响重金属元素形态的因素是土壤p H、土壤植物根际环境,重金属元素迁移的过程还受到土壤类型、含水量以及土壤中有机和无机配体的影响。黏土矿物具有良好的吸附作用,它主要是通过离子交换、配合反应和共沉淀反应来修复土壤中的重金属污染。     

KSF supported 10-molybdo-2-vanadophosphoric acid as an efficient and reusable catalyst for one-pot synthesis of 2,4,5-trisubstituted imidazole derivatives under solvent-free condition

The one-pot three-component cyclocondensation has been developed involving the reaction of benzil with an aromatic aldehydes and ammonium acetate under thermal solvent-free conditions in the presence of a KSF supported 10-molybdo-2-vanadophosphoric acid catalyst. 10-Molybdo-2-vanadophosphoric acid was immobilized on KSF with a 20% loading, which showed the highest catalytic activity. The catalyst was fully characterized using FT-IR spectroscopy, thermal analysis, XRD and SEM analysis techniques. There are several distinct advantages to this protocol, including high yields, short reaction time, operational simplicity and a recyclable catalyst with a facile work-up procedure.     

AlMn复合柱撑粘土负载CrCe催化剂用于氯苯催化降解性能初探

利用高温高压一步法合成系列Al Mn-复合柱化剂,该方法的步骤、物料消耗等较传统制备方法均大大减少,可大大降低生产成本及减少对环境的污染。通过离子交换合成系列Al Mn复合柱撑粘土(Al Mn-PILC)。改变Al/Mn摩尔比、老化温度、老化时间,可调控Al Mn-复合柱化剂的结构,从而影响Al Mn-PILC的结构性能(包括比表面积、孔体积、孔径、层间距等)。通过XRD,N2吸附,高分辨电镜及程序升温还原等实验对材料的结构及性能进行了表征。结果表明:经550℃焙烧4 h后,Al Mn-PILC的比表面积和孔体积可达174.2~246.7 m2·g-1和0.126~0.158 cm3·g-1,层间距可达1.85 nm。经柱撑改性合成的Al Mn-PILC,其负载Cr Ce催化剂对氯苯的催化降解性能远高于原土(Nammt)和单核Al-PILC的,尤其以Cr Ce(9∶1)/Al Mn-PILC的催化活性最佳,在250℃时可完全降解低浓度的氯苯,是一类性能优异的用于有机物催化降解的多孔材料。     

A Two-Scale Model for Coupled Electro-Chemo-Mechanical Phenomena and Onsager’s Reciprocity Relations in Expansive Clays: I Homogenization Analysis

The macroscopic model governing coupled electro-chemo-mechanical phenomena in expansive clays is revisited within a rigorous homogenization procedure applied to the microscopic governing equations which describe the local interaction between charged clay particles and a binary monovalent aqueous electrolyte solution. The up-scaling of the microscopic electro-hydro-dynamics leads to a two-scale approach wherein the macroscopic model appears governed by a fully coupled form of Onsager’s reciprocity relations, mass conservation equations and a modified Terzaghi’s effective stress principle. In addition, the two-scale approach provides microscopic representations for the effective coefficients which are exploited herein to obtain further insight in the constitutive behavior of the electrochemical parameters and the swelling pressure. Among other effects, we show that these microscopic closure relations are mainly dictated by the spatial variability of a microscale electric potential which satisfies a local version of the Poisson–Boltzmann problem in a periodic unit cell, The proposed framework allows to address various relevant still open issues regarding the constitutive behavior of swelling systems, Among them we give particular emphasis on the analysis of the influence of the fluctuation and distortion of the electrical double layer upon the magnitude of the electrochemical coefficients and the precise local conditions for the validity of the symmetry of Onsager’s relations.     

Modelling the capillary imbibition kinetics in sedimentary rocks: Role of petrographical features

The kinetics of capillary imbibition into sedimentary rocks has been measured experimentally and calculated with a model that has been described previously by Hammecker and colleagues (1993). The validity of this model has been discussed and compared to other models. Three limestones, two clean sandstones and three clayey sandstones have been studied. The capillary processes are discussed as a function of their petrography and the pore structures. The role of the grain surface, described by the specific surface area, has been especially studied. The influence of clay coating on detrital grains on capillary processes has been quantified.Nomenclature A weight increase rate by capillary imbibition (A=W/(S ₁t)) - B capillary rise rate (B=l/t) - l height of the capillary fringe or the meniscus over the free water level - g gravitational constant - L height of the geometrical elements - P _a pressure in the air - P _c capillary pressure - P _w pressure in the water - Q flow rate - N _l free porosity - Nt total porosity - r radius of the pore (meniscus) - r ₁ pore access radius (neck) - R pore radius (widening) - R _s particle radius - S specific surface area - S ₁ macroscopical area of the sample surface throughout which imbibition occurs - t time - W weight - z height - surface tension - dynamic viscosity - contact angle - density - _r true density     

膨胀土胀缩性评价中有关问题的研究

膨胀土吸水膨胀、失水收缩，产生地表变形，进而导致建筑物破坏。本文就现行膨胀土胀缩性指标试验及地基变形量评价计算中有关问题进行了研究，认为以天然含水量为起始含水量测定土样胀缩率是不合适的，建议以缩限为起点进行膨胀试验，以胀限为起点进行收缩试验，采用加荷膨胀量（而非卸荷膨胀量）参加有荷载下的膨胀率计算。膨胀土地基勘察必须结合场地条件分析可能影响土体含水量变化的因素，对同一工程采用几种方法评价，互相对比、参照。     

Elastico-viscous properties of deflocculated china clay suspensions — concentration effects

Summary The physical properties of deflocculated china clay suspensions are studied in a combined steady and low-amplitude oscillatory shear flow. Concentration effects are examined and it is shown that, with increasing concentration, an initial shear thinning region is followed by a shear thickening one. Qualitative agreement is obtained between theory and experiment for a range of concentrations of suspensions, all of which exhibit marked elastic properties. The experimental results were obtained using a Weissenberg Rheogoniometer.

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Zusammenfassung Es werden die physikalischen Eigenschaften deflockulierter Suspensionen von Porzellanerde in einer kombinierten stationären und oszillatorischen Scherströmung mit niedriger Amplitude studiert. Der Einfluß der Konzentration wird untersucht, und es wird gezeigt, daß mit wachsender Konzentration sich an den anfänglich allein vorhandenen Bereich mit Scherentzähung ein Bereich mit Scherverzähung anschließt. Zwischen Theorie und Experiment wird eine qualitative Übereinstimmung in einem Konzentrationsbereich gefunden, in dem ausgeprägte viskoelastische Eigenschaften vorhanden sind. Die experimentellen Ergebnisse werden mit Hilfe eines Weissenberg-Rheogoniometers erhalten.

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c phase lag in oscillatory testing - D(t – t) deformation history - F, G non-dimensional complex functions of - complex conjugate ofF - G dynamic rigidity - i - I % increase in mean couple under superposed shear rates - I ₁ moment of inertia of the top platen (i.e. cone) - J amplitude ratio, ₁/ ₁ - K ₁ restoring constant of the torsion bar - q steady shear rate - r, , spherical polar coordinates - t current time - v _i velocity vector - w/w concentration by weight - W a function of andt - ₁ angular amplitude of the motion of the plate - shear rate - /q - apparent viscosity - dynamic viscosity - ^* complex dynamic viscosity - ₀ limiting viscosity at small rates of shear - ₀ gap angle in cone and plate system - ₁, ₂, ₃, ₄,µ ₀ relaxation time constants - shear stress - ₀ unperturbed shear stress - ₁, ₂ kernel functions - angular frequency of oscillation - steady angular velocity of the plate With 16 figures     

不排水双层粘性土地基极限承载力的数值分析

采用弹塑性有限元分析了条形基础作用下不排水条件的双层粘性土地基极限承载力性状。采用修正的地基承载力系数表征,并将不同的几何与土层参数条件下的数值解与上下限解和经典的经验解进行比较。表明弹塑性位移有限元法可以很好地求解地基的极限承载力问题,其求解得到的修正地基承载力系数与基于下限原理的有限元解很接近,而上限解高估了地基的极限荷载值,传统的经验解在某些条件下却偏小。     

土工格栅路堤加筋效果的影响因素分析

土工格栅作为一种新型的土工合成材料,由于具有高强度、低延伸率等特点而被选作主要的路堤加筋材料,在路堤中适当位置加入土工格栅能有效地减少路堤的沉降和侧向变形。本文采用通用非线性有限元程序ABAQUS分析了加筋前后的路堤底部的竖向位移、堤址点垂线下地基深度的水平位移和地表的水平位移,计算中采用D rucker-Prager模型和C lay p las-tic ity模型模拟土体的非线性,土工格栅采用一维杆单元来模拟。通过对加筋层数、筋材模量、软基模量、填土高度和软土层厚度等影响加筋效果的因素进行对比分析,从计算结果分析可知,路堤加筋虽然对软土地基的竖向位移影响不大,但加筋能有效抑制侧向位移的发展,这样增大了路堤边坡的稳定性,分析结果与大多数实际工程的实测资料相吻合。