Selection of mass transfer correlations for rate based liquid-liquid extraction model

A rate-based model for mass transfer in liquid-liquid extraction (LLX) has been developed using three distinct stages of drop formation, drop fall or rise and drop coalescence. Binary diffusivities in infinite dilution as well as for concentrated multicomponent mixtures were used to estimate the Maxwell-Stefan binary mass transfer coefficients for both the phases. The mass transfer resistances associated with these coefficients have been categorized in four configurations. Because of the very large number of computations associated with repeated calculations of mass transfer coefficients, a local model has been incorporated. A comparative study between rate-based and non-equilibrium simulator and our bench scale experiments (LLX of toluene-acetone-water system) has been done. The stage-wise composition profiles of acetone in water and toluene phase of the experimental and simulation runs have been compared by using the relative error square analysis. Based on this analysis, best mass transfer combination and mass transfer resistance model has been selected.