L-抗坏血酸水溶液扩散系数的测定

为进一步补充药类物质水溶液扩散系数的实验数据和研究相关理论模型的实用性,今制备了金属膜池,用氯化钾溶液标定了膜池常数,并用已有可靠扩散系数值的蔗糖水溶液验证了装置的可靠性.测定了298.15K到328.15K不同温度下L-抗坏血酸在水溶液中可溶解范围内不同浓度下的扩散系数.结果表明在相同温度下,L-抗坏血酸水溶液的扩散系数随着浓度的增加而减小;在同一浓度下,随着温度的升高而增加.另一方面Gordon在扩散模型基础上,关联得到一个有温度项的扩散系数半经验模型,计算结果与实验值吻合很好. 同时用精密密度计和粘度计测定了体系相应的密度和粘度,并与浓度进行了关联.     

脂肪族氨基酸在水溶液中扩散系数的测定与关联

用金属膜池法测定了30℃下一些脂肪族氨基酸在水溶液中可溶解范围内微分扩散系数,采用KCl标定膜池常数,并用已有可靠扩散系数值的蔗糖水溶液验证了装置的可靠性.给出了微分扩散系数与浓度及相应的密度和黏度关系式.并考核和外推了一个半经验模型,关联和计算了本实验的数据,结果与实验值吻合得很好.     

用改进的金属膜池法测定二元物系液相扩散系数

为进一步缩短液相扩散系数的测定时间,对传统膜池的结构和实验方法作了改进,测定时间缩短为以前金属膜池的一半,仅约1小时。实验测定了苯、乙苯、邻二甲苯、环己烷和环己酮分别与正庚烷所组成的二元物系在25℃的扩散系数,还测定了甲苯+正庚烷物系在20℃、25℃、30℃、35℃的扩散系数以初步考察温度的影响。由实验数据回归得到了各物系微分扩散系数随浓度变化的多项关联式的系数。对上述物系扩散系数的变化规律进行了讨论。     

对二甲苯在醋酸中扩散系数的测定

为了提供精对苯二甲酸（PTA）生产过程中相关体系的扩散系数,利用金属膜池并用氯化钾水溶液标定了膜池常数。用已有文献值的乙酸水溶液验证了装置的可靠性。测定了298.15-323.15K不同温度下对二甲苯在醋酸中的积分扩散系数,还分别给出了微分扩散系数与对二甲苯浓度的关联式。结果表明在相同温度下对二甲苯在醋酸中的扩散系数随着对二甲苯浓度的增加而减小,在同一浓度下随着温度的升高而增加。     

邻二甲苯在醋酸中扩散系数的测定

利用金属膜池并用氯化钾水溶液标定了膜池常数。用已有可靠文献值的乙酸水溶液验证了装置的可靠性。测定了298．15～323．15K不同温度下邻二甲苯在醋酸中的积分扩散系数,还分别给出了微分扩散系数与邻二甲苯浓度的关联式。结果表明在相同温度下邻二甲苯在醋酸中的扩散系数随着邻二甲苯浓度的增加而减小,在同一浓度下随着温度的升高而增加。     

新的液相扩散系数模型

根据统计力学理论与Eyring绝对速率理论,建立了描述液相扩散系数的理论模型。该模型反映了温度、压力及组成对液相扩散系数的影响。基于此模型,建立了关联高压液相自扩散系数与密度关系的模型方程;导出了二元溶液相互扩散系数与浓度关系的计算方程;建立了计算无限稀释扩散系数的方程。通过对实际物系的验证计算,本文所导出的各方程均能很好地关联计算液相扩散系数,并优于文献方程。     

液相扩散系数与浓度的单参数关联

提出一个液相扩散系数与浓度的单参数关联方程，参数与温度关系不明显，对３８个二元体系的５８６个实验数据点关联结果较好，平均偏差为１．４２％。     

膜池法测定维生素B2在水中的扩散系数

本文用具有金属膜的膜池测定了稀溶液中维生素Ｂ２在水中的扩散系数，同时也考察了温度对该扩散系数的影响。实验结果表明：用金属膜替代玻璃膜使传统膜池法测定扩散系数的时间大为缩短（仅为原来的１／３０），且所测结果真实可靠     

采用泰勒分散法测量蜡分子扩散系数

蜡分子扩散系数是蜡沉积预测模型中非常重要的物性参数。为测量蜡分子（高碳数正构烷烃）在液相体系中的分子扩散系数,建立了基于泰勒分散法的扩散系数测量装置,并对装置操作注意事项进行了详细探讨。采用该装置测量了丙酮水溶液、n-C₆+n-C₇溶液以及甲醇水溶液中溶质在溶剂中的分子扩散系数,以文献值对测量值进行校验,验证了装置的可靠性。分别以n-C₁₈、n-C₂₀、n-C₂₂、n-C₂₄、n-C₂₆为溶质,以n-C₇为溶剂,在不同温度、浓度下测量蜡分子在液相体系中的分子扩散系数,并将实验测量值与Hayduck-Minhas关系式计算值进行比较。结果表明：蜡分子扩散系数随温度升高而线性增大,随溶液中蜡分子摩尔分数的增大而以指数形式减小;在相同条件下,高碳数正构烷烃的分子扩散系数低于低碳数正构烷烃的分子扩散系数。采用Hayduck-Minhas关系式的计算结果比实验测量结果平均小50%,应用于蜡沉积预测时,将低估蜡分子扩散质量流。     

硫化氢在磷酸溶液中溶解度的实验研究

在用过量的五硫化二磷净化磷酸的工艺中,为确定五硫化二磷的最佳投加量和净化的工艺条件,采用气相单循环法,测定了常压下不同温度和不同硫化氢分压下硫化氢气体在磷酸溶液中的溶解度数据。结果表明,在实验范围内,硫化氢的溶解度随温度的升高和磷酸浓度的增加而降低,随硫化氢分压的增加而增加,且呈线性关系,符合一般气体的溶解度规律。用I.H.Cho模型对溶解度数据进行了关联和计算,关联式的显著性水平达0.01,实验值与理论值的平均偏差为1.60%。该结果对磷酸的净化工艺有一定的指导意义。     

Diffusion Coefficients ofl-Lysine Hydrochloride and l-Arginine Hydrochloride in Their Aqueous Solutions at 25℃

The diffusion coefficients** ofl-lysine hydrochloride andl-arginine hydrochloride in their aqueous solu- tions at 25℃ were determined by the metallic diaphragm cell method which is characterized by accuracy, promptness and convenience. Meanwhile, the densities and viscosities of the solutions were also determined. Based on all these data a semi-empirical model for correlating the diffusion coefficients of solid organic salts in their aqueous solutions at 25℃ was proposed. The fitting result of this model is comparatively satisfactory. Compared to a former model, Gordon Model, this model can avoid a number of difficulties and arduous work.     

苏氨酸水溶液在298.15K到328.15K区间液相扩散系数的测定和关联

The diffusion coefficients of aqueous L-threonine solutions were determined from 298.15K to 328.15K by the metallic diaphragm cell method with accuracy, promptness and convenience. Meanwhile, the densities and viscosities of the solutions were also determined and correlated. Based on a seml-empirical model for correlating the diffusion coefficients of some amino acids in their aqueous solutions, a new semi-empirical model for correlating the diffusion coefficients involving temperature was provided, which is more comprehensive and less experiment dependent compared to the previous model. The fitting results are satisfactory. Compared to a former model for correlating the diffusion coefficients of solid organic salts in their aqueous solutions, this model provides significant improvement in correlation of diffusion coefficients with different temperatures avoiding arduous work.     

氨基酸在水溶液中扩散系数的预测

以F ick定律和不可逆过程热力学为基础,结合文献中对扩散系数预测模型的分析,提出了一个氨基酸在水溶液中扩散系数预测的半经验模型。用实验测定的7种氨基酸在水溶液中的扩散系数和一些文献中的扩散系数数据对模型参数进行了拟和。利用该模型对多种氨基酸及尿素在水溶液中的扩散系数进行了计算,计算值与实验值的平均相对误差均小于0.6%。     

氨基酸在水溶液中的扩散系数

There are still limited experimental data of liquid diffusion coefficients in literature. Therefore, the experimental investigation and prediction model are of practical and theoretical significance. The diffusion coefficients of L-serine, L-threonine, L-arginine, in aqueous solution at 298. 15 K were measured respectively by holographic interferometer. The affecting factors of molecular structure and polarity were analyzed and discussed. Finally, a modified semi-empirical model for correlating the diffusion coefficients of solid organic compounds in aqueous solutions at 298. 15 K was proposed with an adjustable parameter added. The average deviation between model prediction values and experimental ones is less than 0.2%, which shows a considerably satisfactory accuracy.     

蛋氨酸在KCl溶液中的解离常数与活度系数

采用改变pH法在25、30和35℃下测定了质量浓度为0.25~4.0 mol/kg的KCl水溶液中蛋氨酸的解离常数,计算得到了蛋氨酸的质子化焓;采用电动势法在25℃测量了0.025~0.200 mol/kg蛋氨酸溶液中浓度为0.1~1 mol/kg的KCl的活度系数,计算得到了KCl溶液中蛋氨酸的活度系数。结果表明,蛋氨酸在KCl水溶液中的解离常数随温度上升而减小、随KCl浓度增加而增大;25℃下,蛋氨酸在KCl水溶液中的活度系数随蛋氨酸浓度增大先减小后增大。运用德拜-休克尔模型和Pitzer模型对解离常数和活度系数的实验数据进行拟合,得到了相关参数,结果表明Pitzer模型的可靠性较好。     

蛋白质-磷酸钾-聚乙二醇双水相体系热力学研究

建立了由蛋白质、磷酸氢二钾、磷酸二氢钾、聚乙二醇所组成的双水相体系的平衡浓度分析测定方法,实验测定了6种蛋白质分子在25℃下的液液平衡分配数据,共23组.将Baskir等的吸附晶格模型和Pitzer的长程静电项相结合,扩展用于含电解质-高聚物双水相体系的热力学计算,仅用7组实验数据进行关联,得到2个吸附能参数,预测了其它16组蛋白质分配系数,结果满意。并提出了蛋白质分配系数与双水相成相物质在两相间浓度差的经验关系式。     

SEPARATION AND ENRICHMENT OF WEAK ORGANIC ACIDS OR BASES BY IMMOBILIZED LIQUID MEMBRANES

A new and effective liquid membrane process to achieve both separation and enrichment simultaneously of weak organic acids or bases was developed. The process utilizes effectively the difference in the apparent partition coefficient of the constituent species between the aqueous and organic phases, and uses the change of the apparent partition coefficients with the hydrogen ion concentration of the aqueous phase. For such a fundamental model apparatus as a diaphragm diffusion cell being operated batch wise, the effects of pK value of solutes, permeability of solutes through the membrane, volume ratio of liquids in two aqueous phases, and pH value of aqueous phase on enrichment factor and selectivity for the solute to be concentrated were discussed analytically. Separation and enrichment were demonstrated using aqueous mixed solutions of fumaric acid and L-malic acid. The results were in good agreement with the theoretical predictions.