Photocatalytic degradation of organic dye using titanium dioxide modified with metal and non-metal deposition

In this study, photocatalytic degradation of methyl orange (MO) as an example of organic dye was investigated using different wt% Pd-loaded and N-doped P-25 titanium dioxide (TiO₂) nanoparticles, as example of metal and nonmetal-doped TiO₂, respectively. The Pd-loaded and N-doped TiO₂ photocatalysts were prepared by post-incorporation method using K₂PdCl₄ and urea, respectively, as precursors. A variety of surface analysis techniques were used for characterization of surface and functional group while using ultraviolet/visible (UV–vis) analysis for monitoring photocatalytic degradation of MO. Kinetic parameters were obtained using Langmuir-Hinshelwood model to determine the degradation rate constants. It was found that the metal-loaded titanium dioxide degraded MO in water at a higher rate than did non-metal-loaded titanium dioxide fabricated by using the post-synthesis method. Also, the pure P25-TiO₂ degraded MO more than N-doped TiO₂ because of decreased surface area by particle agglomeration after being made by the post-incorporation method.     

An investigation on hydride VPE growth and properties of semi-insulating InP:Fe

Growth of highly resistive semi-insulating InP : Fe has been achieved by the Hydride VPE technique in an ambient consisting mostly of nitrogen. After dealing with some thermodynamic considerations pertinent to InP:Fe growth, the experimental growth parameters are described. It is shown that various amounts of iron can be introduced into the InP crystal just by varying the temperature of the iron source. The crystal quality of the grown material is estimated to be good by etch pit density and x-ray diffraction analyses. Current-voltage behaviour and capacitance studies on ann ⁺-SI-n ⁺ structure are explained by invoking the theory of current injection in solids by Lampert and Mark: the experimental current densities at the threshold of each observed regime are compared with the theoretically derived current densities; in the absence of current injection, the measured capacitance is found to be the same as the geometrical capacitance.     

细颗粒LLM-105的制备及其热性能

采用溶剂-非溶剂重结晶技术制备了类球形和立方体结构两种不同晶形的细颗粒2,6-二氨基-3,5-二硝基吡嗪-1-氧化物(LLM-105),重均平均粒径D50分别为2.750 μm和6.206 μm,撞击感度为35.5 cm和34.7 cm.采用热重-微商热重(TG-DTG)和差示扫描量热法(DSC)对LLM-105进行了...     

环氧化天然橡胶制备反应动力学

采用适当提高反应温度、减小甲酸和过氧化氢用量的方法制备不同环氧化程度（Ｂ）的环氧化天然橡胶（ＥＮＲ）,并利用质量作用定理,从ＥＮＲ的制备基本反应式推导出ＥＮＲ的制备反应动力学方程,讨论了Ｂ与反应温度和时间及甲酸、过氧化氢用量的关系。结果表明,用过氧甲酸对ＮＲ进行环化改性制备ＥＮＲ的反应为二级反应,对ＮＲ和过氧化氢的反应则为一级反应。求出的反应速率常数ｋ４为１１２５×１０－４ｄｍ３·（ｍｏｌ·ｓ）－１,活化能为８２６７４ｋＪ·ｍｏｌ－１;Ｂ与过氧化氢用量之间为线性关系     

自熔性烧结含碳球团铁连晶形成动力学过程

链连晶是保持含碳球团热强度的金属骨架。在还原气氛条件下，反应温度600～700℃时，金属铁雏晶形成；铁连晶的形成存在一个临界温度700～750℃。实验表明，低于这个临界温度，即使长时间保温，铁连晶也不易形成；只有当加速率足够大时才会导致铁连晶的形成。在温度确定后，碳的固溶过程是时间的函数，在极短的时间内快速升温是提高含碳球团强度的有效途径。     

草莓色素稳定性研究

本文以提纯的草莓色素为材料，研究了光照、ｐＨ值、温度等因素对其稳定性的影响，结果表明溶液酸度不仅对色素的吸收光谱有显著影响，而且对其稳定性也有一定影响。光照和加热都可以加快色素的降解，这种降解反应符合化学动力学一级反应规律，可用反应速率常数计算不同条件下产品中的色素含量。     

Einflu? von Ethanol auf den Trocknungsverlauf und die Makrostruktur eines Einzel-Zellmaterials aus Apfelparenchym (Sorte Granny Smith)

Ethanol pre-treated apple parenchyma cells are dried in a laboratory vacuum dryer. Various ethanol contents (75 to 95% m/m) and moisture contents (2 to 15 g ethanol-water-mixture per g dry mass) of the cells were adjusted before drying and the influence of these factors on drying behaviour as well as the related structural changes are studied. The initial ethanol content was found to have a significant influence on both, drying behaviour and macrostructure of the dried material. In the case of a low initial value, the ethanol content during drying already drops at moisture contents of about 0.5–1.5 g/g. As a consequence the residual particle moisture consists mainly of water at the end of drying. In contrast to high initial ethanol contents, cells at a low initial ethanol content become strongly deformed on drying. The porosity of the dried material also decreases in the latter case, relatively large and stable aggregates are formed and the water binding capacity of the dried product has diminished on a large scale. The initial moisture content influences the drying behaviour especially on applying low initial ethanol contents. If the initial moisture content is reduced the drop of the ethanol content is shifted towards the end of the drying process. The influence of initial moisture content on macrostructure, however, was found to be small compared with the effect of the initial ethanol content.

     

UHT-Sterilized Peanut Beverages: Kinetics of Physicochemical Changes during Storage and Shelf-Life Prediction Modeling

Strawberry-flavored (S04) and chocolate-flavored (C04 and C20) peanut beverages UHT-sterilized (137 °C, 4 sec or 20 sec) and aseptically filled in Tetra Briks were stored for 6 mo at 5, 20 and 35 °C. Sensory characteristics and kinetics of physicochemical changes were studied. The changes were of zero (pH of S04, and sedimentation and homogenization indices of all beverages) and first (pH of C04 and C20, viscosity and color lightness of all beverages) order. Reaction rate constant and Gibb's free energy increased with temperature. Activation energy followed Arrhenius equation. Deterioration in beverage sensory qualities highly correlated with increase in sedimentation index and decrease in pH and emulsion stability. Shelf-life prediction models were constructed based on sensory and kinetics data. The shelf-life was estimated to be 4–7 mo for beverages stored at 30–35 °C.     

RDX热分解特性及HMX对其热稳定性的影响

利用微热量热实验研究了黑索今(RDX)的热分解特性及奥克托今(HMX)对其热稳定性的影响,运用AKTS分析软件对热分解曲线进行解耦分峰,得到了不受熔融相变影响的热分解曲线和参数,采用Kissinger、Friedman和Ozawa法计算了其热分解活化能。结果表明:RDX是熔融分解型物质,解耦后的RDX熔融峰温为201.07～208.05℃,分解峰温为207.99～232.76℃,活化能为167.70 kJ·mol~(-1),通过Friedman法和Ozawa法计算的活化能变化趋势相同,并得到AKTS软件验证。不同RDX/HMX比例(9/1,8/2,7/3,6/4,5/5)的样品与单质RDX相比,混合样品中RDX的熔融峰温平均降低了8.63,8.32,9.70,8.57,6.50℃,其分解峰温平均改变了1.14,2.01,2.58,3.53,3.47℃;混合样品中RDX活化能为162.32,151.40,149.78,141.14,132.93 kJ·mol~(-1),表明随着HMX比例的增加,RDX活化能降低。