Rheokinetic analysis of the hydration of pentasodium triphosphate in a detergent slurry

The main objective of this research was to analyze, from a rheokinetic point of view, the hydration of pentasodium triphosphate (TPP) in a detergent slurry with a standard composition. A torque rheometer (Brabender Plastograph) with a roller-type measuring system was used. The influence of temperature, TPP quality, system agitation and concentration of dry substances on the total torque of the samples has been studied. From the experimental results it can be concluded that all of these parameters, as well as the reaction time, influence the consistency of the samples. The kinetics of the process are controlled by diffusional resistances.     

Nanostructural characterization of Al(OH)3 formed during the hydration of calcium sulfoaluminate cement

Ye'elimite (Ca₄Al₆SO₁₆) is a main mineral in calcium sulfoaluminate cements. Aluminum hydroxide is one of the products formed by hydration of ye'elimite. To characterize this phase, various aluminum hydroxides were synthesized from their chemical constituents using sol‐gel processing and compared with the aluminum hydroxide formed during the hydration of ye'elimite. The nanostructure of aluminum hydroxide formed during the hydration of ye'elimite was investigated in detail using X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy, inductively coupled plasma optical emission spectroscopy, and ²⁷Al magic angle spinning nuclear magnetic resonance spectroscopy. No evidence was observed that indicated the existence of amorphous aluminum hydroxide in the hydration of ye'elimite. The pH values, thermogravimetric analysis, particle morphology, and Al‐O coordination indicated that the aluminum hydroxide from the hydration of ye'elimite had a crystal‐like structure. The X‐ray diffraction analysis, particle sizes, and ion activity product showed that the aluminum hydroxide from the hydration of ye'elimite had a microcrystalline structure.     

Isobutene hydration over Amberlyst-15 in a slurry reactor

The synthesis of tertiary butyl alcohol (TBA) via isobutene (iB) hydration was studied over Amberlyst-15 sulfonic acid catalyst particles using pure water and aqueous TBA solutions in a bubbling slurry reactor. Preliminary studies to investigate mass transfer effects showed that pore diffusion was present for catalyst particles greater than 165 μm in diameter. Therefore, intrinsic kinetic measurements were made using 90.5 μm catalyst particles and a catalyst loading of 10 kg m⁻³. The kinetic measurements revealed that iB hydration is a pseudo-first-order reaction with an activation energy of 69 kJ mol⁻¹. Isobutene hydration experiments using TBA concentrations in water revealed a hindering effect of TBA, which indicates that separation of TBA formed by iB hydration in three-phase reactors using catalytic distillation is promising from a process design perspective.     

On the kinetics of magnesia hydration in magnesium acetate solutions

High‐quality magnesium hydroxide powders can be produced by hydrating slow‐reacting magnesia in dilute magnesium acetate solutions. The kinetics of this process are very crucial for process design and control, and for the production of a powder with desirable particle morphology. In this work, industrial heavily‐burned magnesia powders were hydrated in 0.01–0.1 mol dm⁻³ magnesium acetate solutions at temperatures ranging between 333 and 363 K. Examination of the magnesium hydroxide produced and the analysis of the kinetic data suggest that the hydration of heavily burned magnesia in magnesium acetate solutions is a dissolution–precipitation process controlled by the dissolution of magnesia particles. The activation energy was estimated to be 60 kJ mol⁻¹, while the reaction order with respect to acetate concentration was found to be about one. © 1999 Society of Chemical Industry     

油基水泥浆水化程度及强度变化规律

使用油基水泥浆堵水是油田开发中后期控水稳油的一项重要方法,但油基水泥浆水化过程以及作用机理的研究很少。研究了油基水泥浆在不同水浆质量比下的强度发展,并通过水泥石试样氢氧化钙含量分析研究了油基水泥浆水化过程。研究结果表明:水浆质量比为0 2的油基水泥浆,其早期强度在53℃和83℃2种温度条件下均出现峰值;水浆质量比为0 1和0 3的油基水泥浆在53℃下后期强度发展有加速趋势,接近和超过了水浆质量比为0 2的油基水泥浆,83℃下油基水泥浆水化后强度比53℃下高,后期强度发展平稳。分析了温度、盐浓度对水泥浆水化程度和水泥石强度的影响。并通过氢氧化钙含量分析了油基水泥浆水化程度。     

反浮选——冷结晶生产氯化钾工艺过程的优化

分析了反浮选-冷结晶生产氯化钾工艺过程中的有关问题,并提出了措施,以求进一步优化工艺过程。     

布草清洗的标准化进展及常见问题分析

作为与人们直接接触的物品之一,布草的清洁程度关系到人身健康.文章系统介绍了布草清洗过程,清洗用设备和洗涤剂相关标准.同时,对清洗过程出现的问题及原因进行了分析,以期服务于众多业内人士.     

胞嘧啶核苷三磷酸的光合合成

研究了用菠菜叶绿体通过光合磷酸化反应将ＣＭＰ合成为ＣＴＰ，本方法具有叶绿体来源方便、生产设备简单、反应时间短、转化率高等优点。     

Effect of particle size distribution of metakaolin on hydration kinetics of tricalcium silicate

The focus of this study is to elucidate the role of particle size distribution (PSD) of metakaolin (MK) on hydration kinetics of tricalcium silicate (C₃S–T₁) pastes. Investigations were carried out utilizing both physical experiments and phase boundary nucleation and growth (pBNG) simulations. [C₃S + MK] pastes, prepared using 8%_mass or 30%_mass MK, were investigated. Three different PSDs of MK were used: fine MK, with particulate sizes <20 µm; intermediate MK, with particulate sizes between 20 and 32 µm; and coarse MK, with particulate sizes >32 µm. Results show that the correlation between specific surface area (SSA) of MK's particulates and the consequent alteration in hydration behavior of C₃S in first 72 hours is nonlinear and nonmonotonic. At low replacement of C₃S (ie, at 8% _mass), fine MK, and, to some extent, coarse MK act as fillers, and facilitate additional nucleation and growth of calcium silicate hydrate (C–S–H). When C₃S replacement increases to 30% _mass, the filler effects of both fine and coarse MK are reversed, leading to suppression of C–S–H nucleation and growth. Such reversal of filler effect is also observed in the case of intermediate MK; but unlike the other PSDs, the intermediate MK shows reversal at both low and high replacement levels. This is due to the ability of intermediate MK to dissolve rapidly—with faster kinetics compared to both coarse and fine MK—which results in faster release of aluminate [Al(OH)₄⁻] ions in the solution. The aluminate ions adsorb onto C₃S and MK particulates and suppress C₃S hydration by blocking C₃S dissolution sites and C–S–H nucleation sites on the substrates’ surfaces and suppressing the post-nucleation growth of C–S–H. Overall, the results suggest that grinding-based enhancement in SSA of MK particulates does not necessarily enhance early-age hydration of C₃S.     

Effect of the densification of C–S–H on hydration kinetics of tricalcium silicate

Effect of water to cement (w/c) ratio and temperature profiles on the densification of C–S–H (calcium silicate hydrate gel) and hydration kinetics of triclinic tricalcium silicate (C₃S) is studied beyond the first day of hydration. Calorimetry and quantitative X‐ray diffraction/Rietveld analysis show that degree of hydration is unaffected by w/c up to 7 days and marginally thereafter. Coupling the degree of hydration with the portlandite content measured from thermal analysis indicate that C/S ratio of C–S–H decreases with increasing w/c. There is a clear increase in the portlandite content with increasing w/c, even though the degree of hydration is unchanged, due to the variations in C/S ratio of C–S–H. On the other hand, when C₃S is initially cured at a lower temperature (20°C) and then at a higher temperature (40°C), there is a significant increase in the reactivity even until 28 days and vice versa. These experimental results were explained using the densified volumetric growth hypothesis, which assumes that hydration kinetics are dependent on the internal surface area of C–S–H.     

真空法动态制冰的非等温结晶动力学

以氯化钠水溶液为制冰溶液,采用真空法制备得到冰浆。从理论上论证非等温结晶动力学模型Jeziorny法和Mo法用于描述冰浆结晶行为的可行性。通过实验测定不同结晶时间下的冰浆含冰率,并建立了冰浆生成过程的非等温动力学方程。研究结果表明：Jeziorny法和Mo法可很好地描述冰浆的非等温结晶过程;Jeziorny模型指数n的值在0.473~0.525间,表明不同实验条件下的结晶机理基本一致,冰晶呈片状增厚生长;Jeziorny模型中的结晶动力学参数K_c、t_0.25和Mo模型中的冷却速率函数F（T）的变化规律均表明高冷却速率可促进冰浆的形成,同时氯化钠的添加会在一定程度上抑制冰晶生长。     

硼精矿加压碱解制备水合偏硼酸钠

采用NaOH-H2O体系加压溶出硼精矿制备水合偏硼酸钠．正交实验结果表明,影响硼溶出的因素顺序为,碱浓度>时间>液固比>温度. 考察了初始NaOH溶液浓度、液固比、反应时间、反应温度、矿石粒度和搅拌速度对硼溶出的影响,最优条件[初始NaOH浓度25%(w)、液固比4:1(w)、反应时间2 h、反应温度140℃、搅拌速度500 r/min、高压釜表压0.2 MPa]下,硼转化率达95.91%. 湿硼泥经三级逆流浆化洗涤(各级洗涤温度90℃、洗水与湿硼泥质量比3:1、时间1 h)可实现Na2O和B2O3的高效回收,烘干的终硼泥Na2O和B2O3含量分别为0.35%和0.45%(w),含42.91%(w) MgO的终硼泥可作为提镁的优质原料. 溶出液添加CaO苛化并高温放置陈化脱色除杂,再降温至25~30℃,恒温结晶6 h后抽滤,结晶率大于70%,晶体用无水乙醇、饱和偏硼酸钠溶液洗涤,40℃烘干12 h,物相为NaB(OH)4,纯度约为90%.     

熔融结晶洗涤塔过滤板的有限元分析

利用ANSYS软件对熔融结晶洗涤塔的主要受力构件——过滤板进行了有限元分析,建立了合理的结构和载荷简化模型.通过有限元分析计算,得到了过滤板的轴向变形和主体应力分布云图,并对过滤板的局部应力和外载荷波动条件下的应力进行了分析.     

含磷洗涤剂对环境的影响及监管建议

分别从水体、动植物及人类三方面详细阐述了污水排放的含磷有机物对环境造成的危害,并且参照国外的经验提出了治理污染的具体建议。     

非晶态晶化导向剂在洗涤剂用4A沸石合成中的应用

用工业原料 ,在常温下合成非晶态晶化导向剂 ,并应用于水热合成体系制备 4A沸石。考察了晶化导向剂加入量以及胶化、陈化和晶化时间等因素对成品的影响 ,得到了结晶粒度高、粒度均匀、钙离子交换度 (>310mgCaCO3/g沸石 )高的产品 ,并使总反应时间由原来的 5h～ 7h降为 80min。     

亚硫酸钙对水泥水化性能的影响

采用XRD、SEM等测试方法研究了亚硫酸钙(CaSO3.1/2H2O)对水泥水化性能的影响,并与石膏(CaSO4.2H2O)进行了对比.结果表明在水泥中CaSO3.1/2H2O不具有石膏那样的调节水泥凝结时间的作用.掺CaSO3.1/2H2O的水泥试样1d强度比掺CaSO4.2H2O试样显著降低,3d后两者强度相近.60d的抗折、抗压强度与28d相比,增幅很小,有的甚至倒缩.CaSO3.1/2H3O和铝酸盐矿物反应,主要生成片状的C3A.CaSO3.     

掺超细矿渣粉水泥石水化进程的试验研究

高掺量超细矿渣粉水泥石早期二次水化较慢，随后水化速度逐渐加快，1年后水化速度已接近空白样。而且由于超细矿渣粉的微集料填充效应和火山灰效应，提高了水泥石的密实度。     

pH值对水泥水化性能的影响

通过测定水泥的凝结时间、强度,并结合XRD、SEM分析,探讨了水泥水化时拌合水的pH值对水泥浆体结构和性能的影响规律.结果表明,随着拌和水pH值增加,水泥的水化速率加快,强度增加,当pH值等于12时,效果最好,通过微观分析可以看出浆体的水化产物多,晶体颗粒小,结构致密,但当pH值超过12时,变化规律相反.     

Analysis of the influence of the injection molding process on the crystallization kinetics of a HDPE

Thermal analyses of microparts in high density polyethylene (HDPE) have shown that the specific processing conditions used in microinjection molding have irreversible consequences on the polymer morphology. This result has been demonstrated with the analysis of the non‐isothermal crystallization behavior of a HDPE with different thermal histories. The evolution of the absolute crystallinity has been analyzed with a relevant model able to separate the primary and secondary mechanisms all over the crystallization duration. This model has emphasized that the evolution of the primary crystallinity with time is different for the microparts compared to the conventional objects. These differences were attributed to variations of the crystallization mechanisms, especially within the nucleation phase, where a persistent melt memory effect of the former chains orientation/extension was assumed. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44239.     

Degradation of Aluminum Nitride Powder in an Aqueous Environmet

The degradation of A1N powder in excess H₂O at room temperature for up to 24 h was investigated. Samples were characterized by various techniques (IR; XRD; SEM; XPS; C, H, N analysis; surface area, particle size, and weight change measurements). The reaction rate was found to be significant, with 80% of the A1N being consumed in 24 h. The initial reaction product was found to be a porous, amorphous, hydrated alumina with stoichiometry near AlOOH. After ∽16 h a crystalline phase, bayerite Al(OH)₃, was detected which became the predominant phase after 24-h contact. The kinetics of the A1N consumption were found to be first order and the reaction rate linear. The kinetic data fitted an unreacted core model with a porous product layer where the surface chemical reaction controlled the overall kinetics.