Concentrations of Individual Ionic Species in the C02-NH3-H20 System from C-13 NMR Measurements

9312513要成功地描述水-弱电解质体系中的相平衡，需要准确地描述液相组成。在现在使用的模型中，计算了这种液体中所有离子物种的浓度，但这些计算的组成并不是基于对真实离子组成的实验测定。为了可靠地评估现有的模型，并开发改进的模型，对液体组成的实验测定将是必不可少的。这项研究的目标是确定典型的水-弱电解质体系中离子物种的浓度。具体地说，我们建议用~(13)C核磁共振来测定CO_2-NH_3-H_20体系中平衡状态下的碳酸盐、重碳酸盐和氨基甲酸酯离子的浓度。碳酸盐-重碳酸盐平衡的行为得到了很好的确立。但是，尽管CO_2-NH_3-H_20体系具有重要的工业和生物意义，涉及氨基甲酸酯的反应的平衡行为还没有在实验上建立起来。有人建议在一定的浓度和温度范围内建立这种行为。***

9312513 Poling The successful description of phase equilibria in aqueous-weak electrolyte systems requires an accurate description of the liquid phase composition. In models that are now used, concentrations of all the ionic species in such a liquid phase are calculated, but these calculated compositions are not based on experimental determinations of true ionic compositions. To reliably evaluate existing models, and develop improved models, experimental determinations of the liquid phase compositions will be essential. The goal of the proposed research is to determine the concentrations of the ionic species in a typical aqueous-weak electrolyte system. Specifically, it is proposed to use carbon- 13 NMR to determine the concentrations of the carbonate, bicarbonate, and carbamate ions in equilibrium in the liquid phase for the CO2 -NH3-H20 systems. The behavior of the carbonate-bicarbonate equilibrium is well established. But in spite of the industrial and biological importance of the C02- NH3-H20 system, the equilibrium behavior of reactions involving the carbamate has not been established experimentally. It is proposed to establish this behavior over a range of concentrations and temperatures. ***