文献类型：期刊文献

中文题名：甲酸钾水溶液气液界面性质的分子动力学模拟

英文题名：Molecular dynamics simulation of the microstructure of the gas-liquid interface of potassium formate aqueous solution

作者：赵宏曼[1];沈卫华[1];方云进[1]

机构：[1]华东理工大学化工学院,化学工程联合国家重点实验室,上海200237

年份：2022

卷号：38

期号：4

起止页码：298

中文期刊名：分子科学学报

外文期刊名：Journal of Molecular Science

收录：CSTPCD;;北大核心:【北大核心2020】；

基金：陕西省自然科学基础研究计划-陕煤联合基金资助项目(2019JLM-20);国家自然科学基金资助项目(21576083).

语种：中文

中文关键词：分子动力学;自扩散系数;表面张力;气液界面密度分布;径向分布函数;比热容

外文关键词：molecular dynamics;self-diffusion coefficient;surface tension;gas-liquid interface density distribution;radial distribution function;specific heat capacity

摘要：采用分子动力学模拟的方法,对不同质量分数的甲酸钾水溶液,在不同温度时的气液界面处水分子的自扩散系数以及气液界面表面张力进行了模拟计算.计算了不同质量分数条件下水分子和离子沿界面法线方向的密度分布,以及50%质量分数的甲酸钾水溶液在温度为323.15 K下离子与水分子之间的径向分布函数.结果表明:分子的自扩散系数随甲酸钾质量分数的增大逐渐减小,随温度升高逐渐增大,表面张力的变化趋势与之相反;随甲酸钾质量分数的增大,气液界面K^(+)和HCOO^(-)的液相密度在某个值附近振荡范围逐渐增大.计算界面处及液相处K^(+)-H,K^(+)-O,HCOO^(-)-O及HCOO^(-)-H之间的径向分布函数,发现气液界面的存在并不影响K^(+)和HCOO^(-)周围水分子结构.计算了不同质量分数条件下溶液的定压比热容和定容比热容,结果表明溶液的比热容随甲酸钾质量分数的增大而逐渐减小.
In order to reduce the energy waste caused by the direct emission of waste heat in the desulfurization flue gas to the atmosphere,potassium formate aqueous solution can be used to recover the waste heat of the desulfurization flue gas.As potassium formate aqueous solution is used as a heat pump working fluid,the gasliquid interface effect on the absorption process cannot be ignored.Therefore,this paper uses molecular dynamics to study the interaction of the gas-liquid interface effect on potassium ions,formate ions and water molecules in potassium formate aqueous solution.Dynamic equilibriums were established on the 25 gas-liquid-gas models.The self-diffusion coefficient and surface tension of water molecules at the gas-liquid interface were simulated for the potassium formate aqueous solutions with different mass fractions and at different temperatures.The density distributions were calculated for water molecules and ions along the normal direction of the interface with different mass fraction.The radial distribution function between ions and water molecules were also calculated for a potassium formate aqueous solution with 50%mass fraction at the temperature of 323.15 K.The results showed that the molecular self-diffusion coefficient gradually decreases with the increase of potassium formate mass fraction,and gradually increases with the increase of temperature.The surface tension gradually increases with the increase of potassium formate mass fraction,and gradually decreases with the increase of temperature.As the mass fraction of potassium formate increases,the liquid phase density of K^(+)and HCOO^(-)at the gas-liquid interface gradually increases in an oscillated range around a certain value,and potassium ions and formate ions tend to be distributed at the adjacent interface of gas-liquid interfaces.The radial distribution functions of K^(+)-H,K^(+)-O,HCOO^(-)-O,HCOO^(-)-H in the liquid phase were calculated at the interface,respectively.The existence of the gas-liquid interface does not affect the structure of water molecules around K^(+)and HCOO^(-).The coordination number was calculated from the first peak and valley position of the K^(+)-O radial distribution function.And the results showed the coordination numbers of K^(+)at the liquid phase and the gas-liquid interface were 3.83 and 3.99,respectively.The increase of coordination number indicates that the hydration effect is enhanced at the gasliquid interface.The specific heat capacities were calculated with different mass fraction at constant pressure and constant volume.The results showed that the specific heat capacity of the solution decreased with the increase of the mass fraction of potassium formate.It can be seen that the potassium formate aqueous solution can be used as a heat pump working fluid to recover water vapor from the desulfurization flue gas,and promote the development of environmental protection.