Analysis of lanthanide extraction using dynamic interfacial tension measurement in the NaNO3 aqueous solution/tributyl phosphate system

HYPOTHESIS: Mass transfer across liquid-liquid interfaces critically determines the efficiency of solvent extraction, yet its intrinsic kinetics remain poorly understood because conventional spectroscopic methods struggle to directly probe interfacial reactions. We hypothesized that dynamic interfacial tension (DIT) measurements, which capture real-time interfacial physicochemical changes, can reveal the kinetic mechanisms of lanthanide extraction without relying on spectroscopy. EXPERIMENTS: and TBP to determine reaction orders and calculate interfacial equilibrium constants. FINDINGS: and second-order dependence on TBP. The interfacial equilibrium constants derived from DIT kinetics agreed well with independently obtained spectroscopic values, validating the method. These results demonstrate that DIT offers a robust, spectroscopy-independent approach for quantifying interfacial reaction kinetics, providing a broadly applicable platform for solvent extraction and other interfacial processes in analytical and physical chemistry.