The study of hydrargillite and γ-alumina conversion process in boehmite in different hydrothermal media

The transition of hydrargillite and γ-alumina in boehmite was investigated under hydrothermal conditions at a temperature of 200°C. The methods of X-ray fluorescnce (XRF) analysis, infrared spectroscopy (IR spectroscopy) DTA, TGA, DSC, scanning electron microscopy (SEM), and thermal desorption were used to study the samples subjected to autoclave treatment in different media. It was shown that, at the hydrothermal treatment of hydrargillite and γ-alumina at the initial stages of treatment, regardless of the conditions of the process and the reaction medium, the formed boehmite is characterized by a high specific surface and low value of the heat effect of the formation and decomposition, which is determined by the weak ordering of its structure.     

Modification of the rate of formation and surface area of ettringite by polycarboxylate ether superplasticizers during early C3A–CaSO4 hydration

Early C₃A–CaSO₄ hydration was studied in the presence of various amounts of two polycarboxylate ether superplasticizers differing in their grafting degree. Hydration and surface area developments were investigated by in-situ NMR relaxometry coupled with BET and DSC during the first 2 h after mixing. This study enables a quantitative comparison of the amount and the specific surface area of the ettringite precipitated along the C₃A–CaSO₄ hydration with or without PCE. The main effect of PCE is to strongly increase ettringite specific area for a variable period. These effects are clearly dependent on the PCE charge and dosage and are reduced when using delayed addition. In this context the NMR relaxometry technique is of particular interest because of its high sensitivity to ettringite and furthermore this in-situ method does not need preliminary preparation likely to damage structure or modify particle arrangement.     

IrO2–SnO2 mixtures as electrocatalysts for the oxygen reduction reaction in alkaline media

In this work, SnO₂ + IrO₂ mixed oxides are studied as electrocatalysts for the oxygen reduction reaction (ORR) in alkaline media by means of voltammetric techniques under controlled mass transfer conditions thanks to the use of rotating (ring) disk electrodes (RDE/RRDE). The oxides, prepared by sol–gel methodology, are supported on the disk electrodes using a thin layer of anionic exchange polymer as gluing agent. The amount of deposited polymer was optimized to avoid any limitation due to the diffusion of reactant/products across the film thickness. The mixed oxides were prepared at the following mole fractions of IrO₂: $ x_{{{\text{IrO}}_{ 2} }} $  = 0.15, 0.31, 0.55, 0.73, and 1. The role of composition was studied in terms of the reaction pathways and the relevant fraction of H₂O₂ production, together with the potentials of the onset of ORR. The fraction of sites able to give proton/hydroxyl and electron transfers is also determined and discussed. The results point to the best performance of low-Ir containing mixtures and to their low sensitivity to the presence of methanol, a key feature in the case of crossover in alkaline direct alcohol fuel cells.     

C4A3(S)分解反应动力学研究

以CaCO3,Al2O3,CaSO4·2H2O为原料制备无水硫铝酸钙(C4A3(S))单矿物,借助X射线衍射和扫描电镜等测试手段研究了C4A3(S)矿物的分解动力学.研究结果表明:C4A3(S)矿物分解反应属于界面化学反应动力学范围,满足化学反应动力学方程:F(α)=ln(1-α)=-Kt ,C4A3(S)矿物分解的化学活化能为449.78 kJ·mol-1.     

亚硫酸钙对C3A和C4AF凝结时间的影响

本文研究了亚硫酸钙对C3A和C4AF含量不同的水泥熟料凝结时间的影响.研究结果表明:亚硫酸钙对C4AF有缓凝作用,而对C3A基本不具有缓凝作用;对于中间相含量较多、C3A含量较高,自身凝结很快的熟料,在水泥中SO3不大于3.5%的条件下,亚硫酸钙不起缓凝作用;对于中间相含量较少、C3A含量较低,自身凝结较慢的熟料,亚硫酸钙有缓凝作用;与二水石膏相比,半水亚硫酸钙在水中的溶解度极低,掺入水泥后,其主要水化产物为单硫型水化硫铝酸钙(AFm).     

WO3/C/Ag3PO4复合材料光催化降解双酚A

以磷酸法制备的活性炭、WO3、AgNO3、Na2HPO4?12H2O为原料,采用共沉淀法制备WO3与C不同含量的系列WO3/C/Ag3PO4复合材料.采用XRD、FTIR、XPS、SEM、TEM和固体紫外漫反射(UV-DRS)技术对其进行了结构表征.在可见光照射下,以双酚A(BPA)模拟污染物,评价WO3/C/Ag3P...     

WO3/C/Ag3PO4复合材料光催化降解双酚A

以磷酸法制备的活性炭、WO3、AgNO3、Na2HPO4为原料,采用共沉淀法制备WO3/C/Ag3PO4复合材料。采用X 射线衍射（XRD）、傅里叶红外光谱（FT-IR）、光电子能谱（XPS）、扫描电镜（SEM）、透射电镜（TEM）和固体紫外漫反射（UV-DRS）技术对其进行表征。结果表明,Ag3PO4与WO3之间形成异质结。在可见光照射下,以双酚A(BPA)模拟污染物,评价WO3/C/Ag3PO4复合材料的光催化降解性能,并提出 WO3/ C/Ag3PO4 复合材料对BPA的光降解机理。结果表明,在一系列光催化剂中, 23% WO3/ 7% C/ Ag3PO4 复合材料在可见光下对10 mg/L BPA水溶液的降解率在90 min分钟达到95%,明显高于单一的Ag3PO4和WO3。经过3次循环重复,BPA的降解率仍能保持在74%,表明WO3/C/Ag3PO4光催化剂具有良好的稳定性。光催化机理表明,自由基?O- 2和h 在降解过程中起主要作用。     

C4A3S对氨基磺酸盐高效减水剂的吸附研究

实验室制备了无水硫铝酸钙（C4A2S）单矿物,采用紫外-可见吸收光谱法测定氨基磺酸盐高效减水剂（简称“AS减水剂”）在C4A3S单矿物及其混合料（C4A3S＋Ca（OH）：＋CaSO4·2H2O）矿物颗粒表面的吸附量,对AS减水剂在水化体系矿物颗粒表面的吸附行为进行了研究。结果表明：C4A3S单矿物和水化混合料对As减水剂的吸附量随初始浓度的增大而增大;对As减水剂的吸附量与极限吸附量随水化时间的延长而增大;在相同吸附时间内,AS减水剂在C4A3S混合料水化体系的吸附量与极限吸附量大于在C4A3S单矿物水化体系的吸附量与极限吸附量。     

MgO对C4A3S↑—水化性能的影响

用ＸＲＤ，ＩＲ和化学分析法研究了ＭｇＯ对Ｃ４Ａ３Ｓ↑－晶体水化性能的影响。结果表明，ＭｇＯ的引入不影响Ｃ４Ａ３Ｓ↑－的晶体形态和晶格尺寸，Ｍｇ＾２＋以间隙方式固溶入Ｃ４Ａ３Ｓ↑－晶体的晶格空隙中。用微量热仪和浆体的线性膨胀率探讨了ＭｇＯ对Ｃ４Ａ３Ｓ↑水化性能的影响。结果表明，ＭｇＯ能延缓Ｃ４Ａ３Ｓ↑－的早期水化，降低其线性膨胀率，因而体积稳定性得到提高。     

从合成气选择性生成C3和C4烃

前言已经报道了几种试图从合成气选择性生成 C_3和 C_4烃的方法。Kodama 等人用 Fe-Mn-Cu/硅藻土催化剂高选择性地制成气态烃“gazol”,道化学公司的研究人员声称负载钼的催化剂能够从合成气生成 C_2—C_5烃,但是在这些催化剂上的产物分布严格遵循 Anderson-Schulz-Flory 分布规律,因为这些催化剂属于费一托催化剂。C_3和 C_4的选择性最大只有33%,而甲烷的选择性为18%.     

掺杂CuO对C4A3(S)矿物形成的影响

研究了掺杂CuO对C4A3(S)矿物形成的影响.结果表明:在1300℃保温1 h,3 h的煅烧条件下,掺杂一定量的CuO,能使C4A3S的形成量增加,但当CuO掺加质量分数超过0.3%时,C4A3(S)含量会降低,保温时间延长对C4A3(S)的形成不利.IR分析结果表明:CuO使C4A3(S)的晶格发生了畸变.在石膏晶型转变前,掺杂适量的CuO可以促进C4A3(S)的形成,同时可以使C4A3(S)的形成温度降低,而且CuO的掺入会使石膏的分解温度降低,过量还会促进石膏的分解.     

以C4A3S和C11A7.CaF2为主要矿物相的水泥水化研究

借助Ｘ射线衍射，扫描电镜，差热分析，能谱分析和微量热仪等现代测试手段研究了以Ｃ４Ａ３Ｓ和Ｃ１１Ａ７．ＣａＦ２为主要矿物相的水泥的水化产物，水泥石结构，水化机理和水化放热规律，对该节能水泥的物理性能作了评价。     

Structural studies on Ca3Al4MgO10 (C3A2M)—A ternary phase in the system CaO–Al2O3–MgO

In a sequence of temperature-dependent solid-state reactions in the system CaO–Al₂O₃–MgO the formation of the ternary phase Ca₃Al₄MgO₁₀ or C₃A₂M has been studied. Whereas the compound could not be prepared at 1200°C, a yield of 85 wt.-% of Ca₃Al₄MgO₁₀ was obtained at 1320°C (incongruent melting point: 1330°C). Powder diffraction data compare well with results of previous investigations from the 1960s. Single crystals of Ca₃Al₄MgO₁₀ could be retrieved from the sinter-pellets. Basic crystallographic data are as follows: orthorhombic symmetry, space group Pbcm, a = 5.14073(8), b = 16.7576(2), c = 10.70977(16) Å, V = 922.61(2) ų, Z = 4. Using synchrotron diffraction data it was possible to solve the crystal structure. Least-squares refinements resulted in a residual of R(|F|) = 0.021 for 1000 independent observed reflections with I > 2σ(I) and 97 parameters. The structure contains [TO₄]-tetrahedra (T=Al,Mg) forming a three-dimensional (3-D) framework whose topological characteristics have been determined. Al-Mg distributions on the different T-sites have been studied. The calcium cations are located in voids of the network. More than 50 years after its first observation our investigation clarifies the crystal structure of a compound belonging to a system that is of relevance for several fields of materials science.     

C3A掺量对C3A-C3S浆体微结构的影响

采用X射线衍射(X-ray Diffraction,XRD)、29Si核磁共振(29Si Nuclear Magnetic Resonance,29Si NMR)、27Al核磁共振(27Al Nuclear Magnetic Resonance,27Al NMR)和BET氮吸附等方法研究了标准养护条件下C3A掺量对C3S-C3A复合浆体微结构的影响.结果表明:C3A的加入可以促进C3S-C3A复合浆体的水化,释放的Al3+可以进入C-S-H凝胶硅氧链上的桥硅氧四面体位置,形成Al掺杂C-S-H凝胶;随C3A掺量增大,复合浆体中C-S-H凝胶的Al[4]/Si和MCL增大;随养护龄期增大,Al掺杂C-S-H凝胶硅氧链上的Al[4]逐渐脱出,进入浆体并转化为Al[6],导致相同C3A掺量下的复合浆体中Al[4]相对含量下降,Al[6]相对含量增长;C3A的加入在降低复合浆体平均孔径的同时,也提高了浆体的孔隙率.     

C．A．染料文摘（142，3，4，5）

142：40071f在极性溶剂中通过对苯醌（的作用）刃天青与试卤灵的激发态猝灭     

C．A．染料文摘（145：2、3、4）

一篇评论,简短的评论最经常出现的天然色素,它表明了这类可更新物料的重要性,尤其在食品和药物工业上。这类物质的大多数的二次代谢物的美好的东西和生物的多样性已被证明。描述的天然染料的是源于植物和动物。叙述的尤其是苯醌染料、吲哚染料、吡喃染料、低聚吡咯染料和异喹啉染料。     

碱对含C4A3S↑—型水泥熟料的影响

本文利用天然原料、高碱工业废渣制成含碱的Ｃ４Ａ３Ｓ↑－系列水泥并借助于ＸＲＤ、ＳＥＭ及强度测试等手段研究了碱对含Ｃ４Ａ３Ｓ↑－型水泥熟料煅烧及相应水泥物理性能的影响。研究表明，碱含量的增加不仅使此类水泥的后期强度降低，也使其早期强度降低，但与普通硅酸盐水泥相比，降低的幅度要小。因此可以利用高碱原料或工业废渣生产含Ｃ４Ａ３Ｓ↑－型的水泥或胶凝材料。     

C11A7.CaCl2和3C2S.3CaSO4.CaF2的水化性能研究

合成了Ｃ１１Ａ７．ＣａＣｌ２和３Ｃ２Ｓ．３ＣａＳＯ４．ＣａＦ２两种矿物，借助ＸＲＤ，ＳＥＭ等测试手段，研究了这二种矿物及其以１：１掺合时的水化历程，结果表明，矿物３Ｃ２Ｓ．３ＣａＳＯ４．ＣａＦ２水化能力较弱，但与Ｃ１１Ａ７．ＣａＣｌ２共掺时，其水化活性可以大大地得到激发。