The Study On Measuring Physical Parameters Of Three Kinds Of Salt Dissolution Process Based On Liquid-Core Cylindrical Lens

Diffusion and dissolution are common physical and chemical phenomena.Solubility,diffusion coefficient and dissolution rate constant are three important physical parameters in the study of solid dissolution.They have also important application value in many fields such as materials,pharmacy,chemical industry,biology and environmental protection.In recent years,the research and development of new drugs and solid compounds have urgently needed the measurement results of their physical parameters and innovative measurement methods.Based on the asymmetric liquid cylinder lens,this paper proposed a new method to simultaneously measure the solubility,dissolution rate constant and diffusion coefficient during the dissolution of solids,and used this method to measure the physical parameters of three salts.The specific work content is as follows:Firstly,This paper has summarized the relevant literature of this research direction and introduced the current research status of the dissolution process,and proposed an optical measurement method based on the liquid-core cylindrical lens to study the dissolution process of solid solutes in aqueous solutions.This method can measure solubility,dissolution rate constant and diffusion coefficient simultaneously through a set of experimental date.And it has the characteristics of easy operation and visualization of the dissolution process.Secondly,based on Fick’ law and Noyes-Whitney equation,this paper introduced the relevant theoretical basis and found the connection between the two based on diffusion length.And the experimental results were in line with theoretical expectations.Thirdly,an experimental measurement system was built with the asymmetric liquid core lens as the core optical element,and the dissolution and diffusion experiments of solid solutes of three kinds of salts（potassium chloride,sodium chloride,ammonium chloride）in aqueous solutions were completed.And this paper has calculated the three physical parameters of solubility,diffusion coefficient and dissolution rate constant.The boundary conditions in the dissolution quality curve are explained by the method of experimental comparison and the calculation results of the diffusion coefficient are verified by the refractive index thein layer movement method.Fourth,this paper explored the static dissolution behavior of ammonium chloride solid solute in aqueous solution under different temperature conditions（293.15K-303.15K）,and the relationship between solubility,dissolution rate constant and temperature was obtained by experimental images.The experimental results showed that the solubility and static dissolution rate constant of ammonium chloride aqueous solution increased with increasing temperature and satisfied the Arrhenius relationship.This paper also obtained the activation energy of ammonium chloride based on the results.