Simultaneous measurement of solubility and diffusion coefficient in partially miscible liquid systems using the...

Dissolution and diffusion in partially miscible liquid systems are prevalent physical phenomena. Parameters governing these processes, such as solubility (S) and diffusion coefficient (D), must be accurately measured for applications in biopharmaceuticals, chemical production, and food manufacturing. However, current common measurement methods are often time-consuming, require complex equipment, or lack accuracy, and they cannot measure both parameters simultaneously. In this study, we proposed a real-time optical image feature extraction method that utilizes the refractive-index spatiotemporal resolution capability of a compound liquid-core cylindrical lens to enable simultaneous assessment of S and D in partially miscible liquid systems. The D values of a glyceryl triacetate-water partially miscible system at five different temperature settings were measured using the equal-refractive-index thin-layer method based on the one-dimensional semi-infinite diffusion model, while S values were determined from the width of the image. The measured data at 298 K agreed with results obtained by other methods, confirming the reliability of the experiment and method. This method features a simple experimental setup and convenient operation, demonstrating broad application prospects.