Liquid-liquid equilibrium (LLE) is a fundamental concept in liquid-liquid extraction, describing the distribution of a solute between two immiscible liquid phases. It plays a crucial role in various industries, such as chemical synthesis, pharmaceutical manufacturing, and environmental remediation. The thermodynamic principles governing LLE, including Raoult’s and Henry’s laws, determine the partitioning of a solute based on its properties and the composition of the solvent mixtures. By understanding LLE, scientists and engineers can optimize liquid-liquid extraction processes for efficient separation and purification of target compounds.