提出了一种计算含盐混合溶剂气液相平衡的新模型,即把活度系数表示为盐的质量摩尔浓度ms和溶剂组成摩尔分数xi的函数,其中盐质量摩尔浓度项表示为盐质量摩尔浓度的二次函数,溶剂组成项由UNIQUAC模型计算。以文献中水-醇-盐和醇-醇-盐的11个体系为例,将新模型用于其气液平衡的计算,关联得到了各体系的模型参数。结果表明:将活度系数表示为ms和xi的函数是合适的;每种溶剂组分气相分压的计算值与实验值吻合良好,最大误差为0.928 k Pa。因此,新模型是一种可广泛用于含盐有机溶液体系气液相平衡计算的方法。
In our previous work,we endowed a new physical meaning of self-diffusion coefficient in Fick’s law,which proposed that the diffusion coefficient can be described as the product of the characteristic length and the diffusion velocity.To testify this simple theory,in this work,we further investigated the underlying mechanism of the characteristic length and the diffusion velocity at the molecular level.After a complete dynamic run,the statistical average diffusion velocity and the characteristic length of molecules can be obtained by scripts,and subsequently the diffusion coefficient was determined by our proposed theory.The diffusion processes in 35 systems with a wide range of pressure and concentration variations were simulated using this model.From the simulated results,diffusion coefficients from our new model matched well with the experimental results from literatures.The total average relative deviation of predicted values with respect to the experimental results is 8.18%,indicating that the novel model is objective and rational.Compared with the traditional MSD-t model,this novel diffusion coefficient model provides more reliable results,and the theory is simple and straightforward in concept.Additionally,the effect of gas pressure and liquid concentration on the diffusion behavior were discussed,and the microscopic diffusion mechanism was elucidated through the distribution of diffusion velocity and the characteristic length analysis.Moreover,we suggested new distribution functions,providing more reliable data theoretical foundations for the future research about the diffusion coefficient.
Xia ChenYan WangLianying WuWeitao ZhangYangdong Hu
