CORRELATION OF PARTIAL MOLAR VOLUMES AT INFINITE DILUTION OF SALTS IN WATER

Salt partial molar volumes at infinite dilution show the unusual behavior of increasing with pressure while at higher temperatures becoming large and negative, reaching negative infinity at the critical point of water. A simplified method for estimating the infinite dilution partial molar volumes for fully ionized aqueous salts up to 350°C and all pressures has been developed using generalized expressions based on fluctuation solution theory. Tabulations of parameters are given for several salts made from 10 different cations and 9 different anions that can be used to predict V^∞ _s for many solutions of practical interest.     

气液色谱法测定正己烷在不同类型固定液中的无限稀活度系数

利用气液色谱法测定了正己烷在正十六烷～正二十三烷、角鲨烷、角鲨烯、二苯甲烷、联苄、丁二酸二正丁酯、丁二酸二异辛酯、已二酸二正辛酯、癸二酸二正辛酯中不同温度下的无限稀活度系数。由Ｆｌｏｒｇ－Ｈｕｇｇｉｎｓ理论预测的正己烷的活度系数与实验值相近，由此进一步得到了二组分体系的相互作用参数值及各溶剂的溶解度参数值。     

DETERMINATION OF INFINITE DILUTION ACTIVITY COEFFICIENTS FOR ORGANIC-AQUEOUS SYSTEMS USING A DILUTE VAPOR-LIQUID EQUILIBRIUM METHOD

A low pressure vapor-liquid equilibrium apparatus has been developed, tested and verified for the measurements of dilute solution activity coefficients for different organic solutes in aqueous systems. Activity coefficient data were measured for aqueous binary mixtures involving methanol, acetone, and benzene at 25°C. The experimental measurements targeted the range of solute liquid compositions extending from the Gas Chromalograph detection limit to 0.3 mole fraction for methanol and acetone, and to the miscibility mole fraction for benzene. Precise extrapolation to determine the infinite dilution activity coefficients (γ_i^∞) was achieved. Instrumental, external and internal consistency tests performed on the acquired data indicate a good level of experimental consistency.     

ESTIMATION OF ACTIVITY COEFFICIENTS AT INFINITE DILUTION OF HALOCARBONS IN WATER AND ORGANIC COMPOUNDS IN HYDROFLUOROPARAFFINS USING NEURAL NETWORKS

Infinite dilution activity coeffcents ( 1) of 19 halocarbons in water and 18 organic compounds in 5 hydrofluoroparaffins over a temperature range of 291 333K have been estimated by the method of neural nets. The network was trained using 351 data points covering 18 halocarbons in water and 17 organic compounds in 4 hydrofluoroparaffins, and generalization test was carried out using the remaining 92 data points covering one halocarbon in water, 17 organic compounds in a hydrofluroparaffin, and an organic compound in 5 hydrofluoroparaffins. Seven inputs are included in the network, namely the temperature, dipole moment, molar refraction and critical pressure of the solute and solvent. The network represented the data with an overall average absolute deviation of 11.8% estimated on the basis of the values of 1. The result obtained could be considered reasonable in view of the wide variations in the values of the input properties and 1 values and the varied nature and size of compounds treated. Among the several variables studied, dipole moment contributed to the correlation the most, followed by the critical pressure. Further study on the applicability of MLR (multilinear regression) method revealed the overwhelming superiority of the neural network over MLR.     

A COMPARATIVE ANALYSIS OF THE DERIVATION OF INFINITE DILUTION ACTIVITY COEFFICIENTS FROM ΔT— x AND ΔP — x DATA

The experimental determination of infinite dilution activity coefficients (γ^∞) of liquid mixtures is carried out by gas chromatographic and ebulliometric techniques. Both methods show inaccuracies due to experimental difficulties.

This paper provides a comparative analysis of the influence of errors in measurements on the evaluation of γ^∞ using ΔT — x and ΔP — x experimental data. It is shown that the errors in the determination of γ^∞ from ΔP — x data are generally lower than those from ΔT — x ones     

立方型状态方程用于液体过量体积的计算

用 SRK、PR 和 YU-LU 三个立方型状态方程对常压下的液体混合过量体积进行了关联计算,涉及的体系包括非极性、弱极性、水及羧酸等强极性混合物。对于对称的非极性、弱极性、极性流体混合物获得了良好的结果,但这种计算方法不适用于含水或羧酸的体系。     

ACTIVITY COEFFICIENTS AT INFINITE DILUTION IN SOLVENTS WITH TWO FUNCTIONAL GROUPS

Activity coefficients at infinite dilution for 26 solutes (paraffins, cycloparaffins, olefins, aromalics, n. chloroparaffins, chloroform, tetrachloromethane, acetates, ketones, alcohols and nitriles) in five solvents containing two functional groups of the same nature were determined by gas-liquid chromatography. The solvents employed were hexanediol, nonanediol, hexanedithiol, dodecanediamine and dodecanedinitrile. The influence of the second functional group is suggested from both the absolute values of the activity coefficients as well as from the selectivity values of these solvents with respect to paraffin-aromatic separation.     

PREDICTION OF MOLAR VOLUMES, VAPOR PRESSURES AND SUPERCRITICAL SOLUBILITIES OF ALKANES BY EQUATIONS OF STATE

A generalized cubic equation of state which can represent all the cubic equations is introduced and thermodynamic property relations for it are presented. Five cubic equations of states with respective mixing rules are used to predict molar volumes and vapor pressures of pure alkanes (from methane till n-tritriacontane) and solubilities of solid wax components (high molecular weight alkanes) in supercritical solvents. They are the RK (Redlich-Kwong), MMM (Mohsennia-Modarress-Mansoori), RM (Riazi-Mansoori), PR (Peng-Robinson), and SRK (Soave-Redlich-Kwon) equations of state. The experimental data necessary to compare the equations of state are taken from the literature. It is demonstrated that the SRK equation of state is more accurate for predicting vapor pressures of alkanes. The RM equation of state is shown to be more accurate for predicting molar volumes of saturated and sub-cooled liquid alkanes as well as molar volumes of alkanes in their supercritical condition. For the solubility of wax components in supercritical solvents it is shown that the MMM equation of state gives the least AAD% for the 270 data points of 10 binary systems studied consisting of a high molecular weight alkane and supercritical ethane and carbon dioxide.     

ACTIVITY COEFFICIENTS AT INFINITE DILUTION BY GLC IN ORGAIC ACIDS AS STATIONARY PHASES

Activity coefficients at infinite dilution of 38 solutes (paraffins, cycloparaffins, olefins, aromatics, n. chloro-paraffins, chloroform, tetrachloromethane, nitromethane, acetates, ketones, alcohols, and nitriles) in four stationary phases were determined by gas chromatography.

The stationary phases employed were Palmitic, Pimelic, Sebacic and Lactic acids.

The effects of the nature of the acids and of the solutes are discussed.     

UNIFAC基团贡献法预测烃类在N-甲酰吗啉中的相平衡数据

用ＵＮＩＦＡＣ基团贡献法预测了苯及烷烃在Ｎ甲酰吗啉溶剂中的无限稀释活度系数及苯ＮＦＭ的二元汽液平衡数据。为提高预测精度，对ＵＮＩＦＡＣ的交互作用参数进行了改进。     

THERMODYNAMICS OF ALKANOLAMINE+WATER SYSTEM

Design of gas treating processes requires knowledge of the vapor-liquid equilibrium behavior of the (acid gas + aqueous alkanolamine) system. The present study is focused on thermodynamics and associated nonideal behavior of binary MEA + H₂O, DEA + H₂O, and MDEA + H₂O systems, which is required to predict the vapor-liquid equilibrium of acid gases such as CO₂ and H₂S over aqueous alkanolamine solutions. Determination of binary interaction parameters and analytical prediction of infinite dilution activity coefficient, heats of solution at infinite dilution, the excess Gibbs free energy, and excess enthalpy for nonideal alkanolamine-water systems are the objectives of this study.     

熔盐中Al-Ti合金共沉积的电极过程

应用循环伏安等电化学测量方法，研究了在低温（２０００Ｃ）熔盐体系中铝阴极还原及铝、钛共沉积的电极过程．提出铝、钛共沉积的电极过程为二步反应：即Ｔｉ３＋首先还原为Ｔｉ２＋，继而为Ｔｉ２＋与Ａｌ３＋离子的共沉积，形成Ａｌ－Ｔｉ合金镀层．     

用Ha′la限制式结合γ~∞数据推算多元汽液平衡

提出了一种把Wilson方程参数间关系——Ha′la限制式和无限稀释活度系数相关联,用以估算三元系汽液平衡的方法。用汽液色谱测定挥发性溶质在不挥发性溶剂及混合溶剂中无限稀释活度系数,与Ha′la限制式相结合预测三元系汽液平衡,同文献位相比较:从Dortmund数据库的汽液平衡数据中选取了13组同时具有三元系和二元系汽液平衡数据的体系,用拟合和无限稀释活度系数及Ha′la限制式结合的方法求取Wilson参数,进而预测汽液平衡,与文献值相比较;又在三元系的三个二元系之间用同样办法进行相互推算;又利用两个二元系和三元系的一点数据进行预测;所得结果均较满意。为证明所用方法的可靠性,并对预测误差的置信度上限作了相应的估算。     

压滤机在铬盐生产中的应用

介绍几种压滤机在铬盐生产中的应用及其特性,并根据使用情况,对设备生产厂家提出了一些建议,以供参考改进。     

Thermodynamic Models for Hydrogen-Containing Systems at Infinite Dilution

For a supercritical gas such as hydrogen, thermodynamic models for Henry's constant, partial molar volume, and partial molar enthalpy are sufficient in representing the thermodynamics of hydrogen-containing systems at infinite dilution. This work presents a generalized method and correlations for Henry's constant in binary systems containing hydrogen as a function of temperature. Experimental vapor–liquid equilibrium data were used to obtain this Henry's constant correlation with (i) three specific parameters, (ii) one specific parameter, and (iii) no specific parameter. These three Henry's constant correlations for hydrogen vary in the degrees of generalization and accuracy. A generalized corresponding states correlation for partial molar enthalpy of hydrogen in hydrocarbon systems at infinite dilution was derived from the newly developed Henry's constant correlation and from a correlation for infinite-dilution partial molar volumes of hydrogen available in the literature. Overall, this work provides the most extensive method for infinite-dilution thermodynamic properties of hydrogen-containing systems.     

预分离色谱法直接测定微量组份无限稀释活度系数

预分离色谱法可直接测定混合物中微量组份的无限稀释活度系数(γ~∞),而不必把此组份从混合物中分离出来。主要由四步组成:被测组份的预浓缩,被测组份的定性,选择预分离柱和γ~∞的测定。预浓缩样品经过预分离柱分出被测组份,然后进入测量柱测定γ~∞。此方法简捷、可靠与常规以纯溶质进样的色谱测y~∞的方法具有相同的测定精度,可广泛用于缺少纯样的场合。用此法测定了戊烯-1-炔-4、丁炔-2在若干酸醇中的γ~∞,分别求得了修正和未修正的UNlFAC参数,对kikic修正模型其值为ac=c,CooH=694.9(K)acooH,c=c=-99.08(K),ac=c,oH=812.99(K),aoH,c=c=143.36(K)     

二苯胺型重氮盐在乙醇中的光,热分解

芳基重氮盐在乙醇中的光热分解已有很多研究［１～７］,但分解产物及提出的分解机理不完全统一．就一般的观点,芳基重氮盐在光热的作用下可以采取异裂或均裂的分解方式,以苯基重氮盐为例,可表示如下：式中Ｘ－为Ｃｌ,ＨＳＯ４,ＢＦ４等负离子异裂产生芳基正离子中间...     

氨基磺酸水溶液中含羟基季铵盐类的缓蚀作用的研究

研究了合成的十二烷基二甲基（２－羟基）乙基氯化铵等含羟基季铵盐，对２０＾＃碳钢在１０％氨基磺酸水溶液中的缓蚀作用。结果表明：这一类季铵盐在酸性介质中有良好的缓蚀作用，随着烷基链的增长，缓蚀效率增加。     

THE EFFECT OF PARTICLE DILUTION ON WETTING EFFICIENCY AND LIQUID FILM THICKNESS IN SMALL TRICKLE BEDS

Partial wetting in small scale trickle bed reactors results in incorrect determination of intra-particle apparent kinetic parameters as well as in erroneous reactor scale-up. Although a dilution of catalyst particles with inert fines improves the catalyst wetting efficiency, it does not guarantee full external catalyst wetting at all superficial liquid mass velocities. In this work, a method is presented to relate the wetting efficiency obtained at different operating conditions and at different laboratories for diluted and non-diluted beds. Liquid film thickness in diluted and non-diluted beds is estimated. The effect of the operating conditions on partial wetting and liquid film thickness is discussed.     

MEASUREMENT OF WATER DIFFUSIVITY IN AQUEOUS LITHIUM BROMIDE AND LITHIUM CHLORIDE SOLUTIONS

A relatively simple method was employed for measurement of water diffusivity in aqueous lithium bromide and lithium chloride solutions. The twin bulb apparatus used for these measurements was developed using an analogy between this apparatus and the conventional diaphragm cell apparatus. Tritiated water (TOH) was used as a tracer for these experiments because of its chemical similarity and proximity to the molecular weight of water. High tracer activity used at the beginning of the experiments allowed the use of relatively shorter time duration for each experiment (s;≈ 20 h) and a quasi-steady state equation to calculate the diffusivity from the observed tracer activity data

Initially, the water diffusivity in lithium bromide solutions for concentrations varying from 0.5 M to 3 M (22.1 weight percent) was measured to obtain a comparison with published values. The lithium bromide concentration was further varied from 3 M to 11 M (57.4 weight percent) to obtain data in the concentration range usually employed in absorption cooling applications, which is near the solubility limit. The water diffusivity was found to vary with lithium bromide concentration, and to have a maximum of 16.7 × 10^-10m²/s at 4 M. These diffusivity values were also compared with those obtained using an equation proposed by Rosevaere etal. (1941) for nonideal solutions. The water diffusivity in lithium chloride solutions was measured at concentrations of 7 M (25.7 weight percent) and 8 M (28.87 weight percent) to obtain a comparison with published values. The lithium choride concentration was further varied from 8 M to 13 M (43.24) weight percent) to gather data beyond those of other researchers. Similar to the trend of water diffusivity in lithium bromide solutions, water diffusivity in lithium chloride solutions was also found to vary with concentration with a minimum of 6.2 × 10^-10m²/s near the solubility limit.