Advanced Approaches to Immersion Nondestructive Measurements of Ionic Conductivity Gradients in Multiphase Aqueous Environments: A Review

The gradient of the ionic conductivity is a critical factor for assessing the spatial variability of ionic distributions, as evident in the complex dynamics that are characteristic of various aqueous environments. Accurate observations of the conductivity fluctuations resulting from ion movement in solutions are essential for determining the purity of the aqueous phase and the surrounding environment. This study presents a comprehensive overview of nondestructive immersion measurements of ionic conductivity gradients. The phenomena associated with these gradients arise from intrinsic differences in the medium physical properties, the wide variety of ion characteristics, the intricacies of interfacial conditions, and the interactions between chemical mass transport phenomena in aqueous settings. A thorough review of the latest advancements in ionic conductivity gradient detection methodologies based on electrical, optical, and acoustic principles is presented, highlighting the key milestones and breakthroughs achieved to date. Furthermore, the ionic conductivity gradient formation principles and underlying mechanisms are reviewed, and different electrode measurements, inductively coupled systems, optical refractometry systems, and acoustic velocity evaluation measurements are classified. Additionally, the applications of nondestructive immersion measurements in water quality monitoring, oceanographic research, chemical production, industrial process control, and other ion-involving electrochemical reactions are summarized. The prospects and future directions for enhancing the cost-effectiveness of field nondestructive testing and long-term stability of the equipment using new materials, structures, and AI technologies are also discussed. The technological innovation in nondestructive immersion measurements is expected to catalyze transformative changes in the optimization of chemical production, ushering in a new era of efficiency and control in industrial processes.