L-抗坏血酸水溶液扩散系数的测定

Determining the Diffusion Coefficients of Aqueous L-Ascorbic Acid Solutions

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。

In order to provide the experimental data of liquid diffusion coefficients for medicative aqueous solution and to obtain a practical theoretical model for the prediction of liquid diffusion coefficients, a metallic diaphragm cell was prepared and its cell constant was determined by measuring the diffusion coefficient of aqueous KC1 solutions in it at 25℃. The reliability of the device was verified by comparing the measured diffusion coefficient of the sucrose-water system in it at 25℃ with the well known data in literature. The diffusion coefficients of aqueous L-ascorbic acid solutions at 298,15-328.15 K were determined by this metallic diaphragm cell, Results show that diffusion coefficients of aqueous L-ascorbic acid solutions decrease with the concentration increase at the same temperature and increase with the temperature increase at the same concentration. Meanwhile, based on the Gordon model, a semi-empirical model containing temperature for correlating the diffusion coefficients was proposed. The fitting result of this model is comparatively satisfactory. The data of density and viscosity of aqueous L-ascorbic acid solutions were measured and correlated with the concentration of the solution.