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91.
92.
用浊点法测定了四氟硼酸1-丁基-3-甲基咪唑—水—碳酸钠体系在常压30℃下的溶解度曲线及密度曲线,并用经验方程进行了关联。用浊点—密度法测定了该体系的液液相平衡数据,绘制了相应的相图。结果表明:双水相体系一相以离子液体和水为主,碳酸钠的含量很少,另一相以碳酸钠和水为主,离子液体的含量很少。该体系既可作为萃取分离体系,也可作为从水溶液中分离回收离子液体的初步体系。用Othmer-Tobias+Bancroft经验方程对相平衡数据进行关联,最大相对误差为94.99%, 最大平均相对误差为15.69%,关联结果不理想。提出用Othmer-Tobias经验方程+溶解度方程对其进行关联,最大相对误差为4.52%,最大平均相对误差为2.77%,关联精度较高,该方法可适用于有一组分含量较低的体系的液液相平衡的关联计算。 相似文献
93.
In this review, which consists of two parts, major interactions between nitrous oxide (N2>O) and soil solution are described. In the first part, as an introduction, concentrations of dissolved N2>O in different aqueous systems are summarized. An inventory of data on maximal N2>O concentrations in soil solution (up to 9984 g N2>O-N l–1>) and in soil air (up to 8300 ppm) from literature is presented. The peak N2>O concentrations represent a N2>O supersaturation in the soil solution up to 30000 times with respect to ambient air and a soil air N2>O concentration about 25000 times higher than in the atmosphere. The main physico–chemical parameters (solubility, diffusion) controlling N2>O distribution between soil solution and soil air are outlined. The influences of cultivation practice, nitrogen turnover, water content and temperature on N2>O a ccumulation in soil solution and soil air are reviewed. In the second part some models of N2>O dynamics in soils are discussed with emphasis on N2>O transport processes. A simple qualitative scheme is developed to categorize the effects of the soil solution on N2>O dynamics in soils. In this scheme the temporary, intensive N2>O oversaturation of the soil solution is interpreted as a result of gas diffusion inhibition by water (barrier function of soil solution) resulting in an accumulation of N2>O. In addition, N2>O supersaturation is an indication that transitory much N2>O can be stored in the soil solution (storage function of soil solution). Where the soil solution flows up-, down- or sidewards it can act as a relevant transport medium for dissolved N2>O (transport function of soil solution). This scheme is applied to examples from the literature. 相似文献
94.
Colloidal silica particles are prepared via a sol gel technique carried out in an inverse microemulsion of water in a toluene solution of tetraethoxysilane (TEOS), stabilized by either an anionic surfactant AOT or isopropanol. Functionalized material was obtained using a functional coupling agent (RO)3Si(CH2)3
X, X being a functional group such as methacryloyl, thiol, vinyl, amino group, or a chlorine atom. Functionalization can be carried out either directly via the direct copolycondensation of TEOS and the coupling agent, or in a two-step process involving a core-shell polycondensation of the coupling agent onto preformed silica particles. Kinetic studies of the copolycondensation are carried out using either29Si NMR analysis or liquid chromatography. They show that the consumption of TEOS is more rapid than that of the coupling agent. The materials are characterized both chemically (elemental analysis, FTIR,13C and29Si NMR CPMAS analysis), and by their particle size. The silica functionalized with a polymerizable methacryloyl group is encapsulated by a polymer layer in an inverse emulsion polymerization of acrylic acid. After inversion of the emulsion in water, the resulting material is covered with a layer of hydrophobic polymer in a conventional emulsion polymerization. 相似文献
95.
Peter?S.?Piispanen Marcus?Persson Per?Claesson Torbj?rn?NorinEmail author 《Journal of surfactants and detergents》2004,7(2):147-159
Several novel and some previously known, mostly sugar-based, surfactants have been synthesized and some of their surface properties
have been characterized and compared with those of commercial nonylphenol ethoxylates. The surfactant solubility in water,
ethanol, and dodecane was studied. The properties of these compounds as emulsification agents in systems composed of the surfactant
with water/isopropyl myristate, water/rapeseed oil, and water/dodecane are presented. The aqueous solubility of the surfactants
follows the general trend expected from their hydrophilic-lipophilic balance according to Griffin (HLBG), but it is also clear
that the nature of the headgroup and the structure of the nonpolar part affect the solubility in a manner not aptured in the
standard HLBG concept. An ester or amine group as the connecting unit between the hydrophile and the hydrophobe produces a
more water-soluble surfactant than the corresponding amide derivative. Some effective emulsifiers were found. For instance,
the surfactants with a dehydroabietic nonpolar group appear to be promosing emulsifiers. Most sugar-based surfactants were
able to form macroemulsions of up to around 2 wt/vol% of oil. The stability of many of these amulsions was very high, extending
for months. 相似文献
96.
97.
综述了微孔塑料成型过程中聚合物/气体均相体系形成的影响因素。表征均相体系的重要参数是气体在聚合物中的溶解度,因此通过SEM、玻璃化转变温度法、粘度法等间接方法来衡量溶解度,可以间接表征均相体系。对影响均相体系形成的压力、温度、时间和剪切作用等工艺条件进行了分析。适当增加压力、升高温度有利于均相体系的形成.剪切作用可提高气体的扩散性和溶解性,同时还可大大缩短均相体系形成所需要的时间。 相似文献
98.
赵鑫 《电脑编程技巧与维护》2014,(12):26-27
经典的PageRank算法对所有出链网页采用平均分配链出权值的策略,这种方式会导致网页PR值计算的不准确性。通过对链出网页的重要性进行分析,优化链出权值的分配策略,实验结果表明,改进的PageRank算法使得页面排序的结果更加优化。 相似文献
99.
A supercritical fluid extraction method has been applied to test the feasibility of tocopherol concentration from soybean
sludge with carbon dioxide at temperatures and pressures ranging from 35 to 70°C and 200 to 400 bar, respectively. The supercritical
solubility of the esterified soybean sludge was over 4–6 times greater than that of the original soybean sludge. By a simple
batch-type one-stage method the tocopherols in the esterified soybean sludge could be concentrated up to 40 wt%. The overall
results of the present study show that soybean sludge initially containing about 13–14 wt% tocopherols may require a countercurrent
multistage column to be highly and effectively concentrated. 相似文献
100.
Concentrated inverse emulsion polymerization was used for making chromatography columns (based on crosslinked polystyrene divinylbenzene (PS‐DVB)) with pore sizes less than 10 μm. According to DSC‐thermal gravimetry thermograms, it was confirmed that the residual monomer concentration after polymerization process is negligible. For application of these columns in chiral chromatography, the β‐cyclodextrin is chemically fixed on the PS‐DVB resin pore surface. The presence of hydroxyl groups in the PS‐DVB resin after chemical modification was confirmed by FTIR spectroscopy. By chemical modification of the PS‐DVB resin, thermal stability increased up to 446°C. The structure of columns was analyzed by scanning electron microscopy (SEM). SEM evaluations showed that the porous structure of PS‐DVB resin was maintained intact after the chemical modification with β‐cyclodextrin. According to X‐ray data, presence of the crystalline domain that is related to β‐cyclodextrin is confirmed.© 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 857–863, 2006 相似文献