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71.
Andrew P. Karman Susan E. Ebeler Nitin Nitin Stephanie R. Dungan 《Journal of the American Oil Chemists' Society》2021,98(10):979-992
Using headspace solid-phase microextraction (HS–SPME), equilibrium distributions could be determined for hydrophobic solutes in closed systems containing vapor and aqueous solution, either in the absence or presence of two short-chain phospholipids, dihexanoyl-phosphatidylcholine (diC6PC) and diheptanoyl-phosphatidylcholine (diC7PC). Without phospholipid, HS–SPME with short extraction times was used to measure water–vapor partition coefficients for d-limonene at five temperatures within 15–40°C, with results in good agreement with existing literature. The temperature dependence of yielded the enthalpy of volatilization 34.5 kJ/mol for limonene. At 25°C, solubility values for d-limonene, 1-octanol, and n-decane were obtained using similar measurements above aqueous solutions of various solute concentrations. Short-time HS–SPME extraction of limonene in closed vials containing diC6PC or diC7PC micelles was also used to evaluate distributions of solute between vapor, aqueous dissolution, and micelles, for various surfactant concentrations at 15–40°C. Resulting vapor phase concentrations were analyzed using a mass balance and measured values, to obtain micelle–water partition coefficients and critical micelle concentrations. in diC6PC solutions (1–2 mM−1) weakly increased with temperature, but decreased significantly with increased temperature for diC7PC micelles (2–4 mM−1). Solubilization in short-chain PC micelles has previously received little attention, and our results show that the extent of partitioning into these diacyl (i.e., two-tailed) lipids is comparable to that for single-tailed anionic or nonionic surfactants. 相似文献
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74.
The use of partitionable solutes, e.g., aliphatic alcohols, to enhance the recovery of trapped oil in reservoir rock, has been simulated using a ballotini-packed column initially flooded with kerosene, and subsequently lowered to an irreducible value by a water drive. Introduction of a “slug” of an alcohol effected an increased recovery, with n-propanol and sec-butanol giving the highest yields. Previous workers attributed such increased recovery to the formation of a “soluble front”, in which both oil and connate water are completely dissolved. However, we obtained similar recoveries using slugs with initial compositions lying on the miscibility boundary, which could not form soluble fronts. It was therefore concluded that Marangoni-induced oscillation of the trapped drops is the more likely explanation of the enhanced recovery. 相似文献
75.
采用液态金属冷却技术淬火得到了温度梯度在80K/cm时Al-1.5Cu-3Zn合金的固液界面,使用光学显微镜观察了界面形貌,发现在生长速度为0.1和7.1pμm/s时试样分别为胞状生长界面和枝晶生长界面。用SEM和EDS测量了溶质分配,计算出了A1-1.5Cu-3Zn合金中Cu和Zn的平衡分凝因数为0.31和0.58。采用活度模型和浓度模型进一步计算了平衡分凝因数,发现两个模型计算出的Cu和Zn的平衡分凝因数一致,并讨论了模型计算值和试验值之间的差异。 相似文献
76.
Dialysis membrane was prepared by a phase inversion method using a new polyether-segmented nylon which dissolves in common organic solvents such as dimethylsulfoxide. The polyether-segmented nylon contained poly(ethylene oxide) block and nylon block (random copolyamide: Ny69/M10) prepared by sebacic acid, azelaic acid, m-xylenediamine, and hexamethylenediamine. The morphologies and permeability characteristics of the membranes were investigated. It was shown by scanning electron microscope observation that the membrane had a fingerlike structure when dimethylsulfoxide was used as a polymer solvent, and a spongelike structure when an additive such as calcium chloride was added to the polymer solution. The high permeability for the solutes such as urea and vitamin B12 were observed in comparison with the polyether-segmented Ny610 membranes prepared by a phase inversion method. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1731–1737, 1997 相似文献
77.
在近α型TG6钛合金两相区淬火过程中,对初生α相αP周围形成的块状组织αm进行表征研究,块状组织αm与αP存在明显的界面,合金元素Al、Sn和Zr浓度介于αP和β基体之间,EBSD分析结果表明αm取向与αP保持一致。在冷却过程中,αP周围β基体中合金元素扩散受到限制,进而在局部过渡成分区域通过扩散转变形成αm组织。当固溶温度从1040℃提高至1060℃,同时保温时间从30 min减少为5 min,溶质元素扩散受限,αm体积分数从5.2%提升至30.7%。 相似文献
78.
正渗透是一种利用渗透原理的新兴膜技术,近年来在国内外受到了广泛的关注。解析该过程中溶剂水的传递和驱动溶质的反向传递对其发展和应用至为关键。首先开展了两种膜的取向下,正渗透过程中的水通量和溶质反向摩尔通量的实验研究。当驱动溶液在膜分离层侧时,水通量更高,而溶质反向摩尔通量更低,表明水的传递对溶质的反向传递有限制作用。而后分别考察了不同的单一溶质和二元混合溶质作为驱动溶质时,水和溶质的传递现象。当单一中性溶质或电解质作为驱动溶质时,水通量和溶质反向摩尔通量均随驱动溶液浓度的升高而增大;在相同操作条件下,驱动溶质的扩散系数越小,溶质反向摩尔通量越小;中性溶质与电解质混合溶液为驱动溶液时,溶质分子之间存在耦合传递效应。 相似文献
79.
采用耦合传质的格子Boltzmann方法模拟风化壳淋积型稀土矿中稀土浸出的溶质传递过程,在验证模型有效性的前提下,获得了稀土矿填充孔隙中流体流动的速度分布和伴随流动过程的溶质浓度分布. 通过考察浸取流速对溶质传递过程的影响,得到最佳浸取流速,约为0.25~0.35 mm/s,使溶质传递效率最高. 浸取流速小于0.2 mm/s导致浸取周期过长、浸取剂消耗量大;浸取流速大于0.4 mm/s引起沟流,导致稀土不能有效地浸出. 此外,模拟所得传质舍伍德数Sh随雷诺数Re的变化关系与经验关系式吻合,表明提出的模型可用于预测稀土浸出过程的溶质传递规律. 相似文献
80.
Crystal growth of Cd0.9Zn0.1Te (CZT) using the Liquid-phase Vertical Bridgman method (LPVB) is numerically simulated and analyzed using the simulation software of Comsol Mutiphysics. The influence of curvature on the solid-liquid interface is studied, and the radial solute segregation is calculated for three kinds of growth method. The energy dispersive X-ray (EDX) detector of an SEM was used to test the concentration of Zinc. And all the calculated data are in agreement with the results of the experiments numerically. The diffusion transported mechanism during supercooling of CZT crystal growth was studied and the freezing point curve and the thickness of the boundary layer for different values of G (temperature gradient) and v (growing rate) are discussed. 相似文献