Study On Measuring Diffusion Coefficient Of Different Concentrations Of Liquid Based On Asymmetric Liquid-core Cylindrical Lens

Liquid diffusion coefficient is one of the important physical parameters,which describes the diffusion process and characterizes diffusion speed.It is also an important data for researching the mass transfer process and calculating the mass transfer rate.Accurate measurement of Liquid diffusion coefficient is of important applications in environmental,biological,medical and other fields.Compared with the diffusion measurements between gas and gas,or solid and solid,the liquid diffusion coefficient is obtained usually by experimental methods.However,the traditional measurement of liquid diffusion coefficient is very complicated,so the data of the liquid diffusion coefficient between different materials and systems are very scarce.In this thesis,based on focal plane imaging principle of cylindrical lens and an asymmetric liquid-core cylindrical lens designed by us,the method of thin liquid layer with an equivalent refractive index(RI)has been used to measure liquid diffusion coefficients of different diffusion systems and liquid concentrations.The main research contents and results are as follows:1.The diffusion coefficient of 0.33 mol/L KCl solution at room temperature(25 ?)was measured,and the reliability of the experimental system was verified.The diffusion of 0.3 3mol/L to 3mol/L KCL was taken as an example,the effect of different liquid layer with an equivalent RI on measurement result was investigated.The experimental results show that if the liquid layer chosen is of the same RI as the upper solution,the measured liquid diffusion coefficient is correct and consistent with the literature values.2.The diffusion coefficients of KCI aqueous solutions of 0.33,0.50,1.00,1.50 and 2.00 mol/L diffusing on 3.00 KCl mol/L aqueous solutions,which is located at the lower part of diffusion cell,were measured at room temperature by the method of thin liquid layer with an equivalent RI.The results show that if the liquid layer chosen is of the same RI as the upper solution,the measured diffusion coefficients are reliable values.3.By means of the method of thin liquid layer with an equivalent RI at the room temperature,the diffusion coefficients of ethylene glycol aqueous solutions of infinite dilute,20%,40%,60%and 80%diffusing on pure ethylene glycol solution were measured;three glycol triethylene glycol aqueous solutions of infinite dilute,20%,40%,60%and 80%diffusing on pure triethylene glycol solution were also measured.The measured values are consistent with the literature values.