Extraction of dye from aqueous solution in rotating packed bed

In this research work, liquid–liquid extraction via three different systems has been investigated for determination of holdup, flooding velocities and holdup at the flooding points in a multistage column extractor. The effects of various parameters including rotor speed and dispersed and continuous phase velocities were studied. The results showed that the enhancement of rotor speed and dispersed and continuous phase velocities would enhance the dispersed phased holdup. There was a significant increase in the holdup at the flooding points with an increase in the rotor speed because of the smaller drops formation. New correlations were also developed for prediction of the flooding velocities, holdup at flooding points and dispersed phase holdup in the multistage column extractor. The results of the proposed correlation were compared with the experimental data obtained from the literature and the present investigation. Findings of this study demonstrated that the proposed correlations give accurate predictions for flooding characteristics.

Experimental investigation of dispersed phase holdup and flooding characteristics in a multistage column extractor

Single drop mass transfer data have been obtained for the ternary and quaternary systems toluene–acetone–water and toluene–acetone–phenol–water. The addition of surfactant was also made for some experiments. The results were assessed using a simple single solute mass transfer model and a non-equilibrium model based on the Maxwell–Stefan equations. In both cases allowance was made for the effects of interfacial contaminants or solutes by using empirical correlations for the mass transfer coefficients which were developed to take contamination into account. The non-equilibrium model rate-based calculations gave different results to the single solute model in the case that the two main solutes were undergoing simultaneous mass transfer. It is considered that the phenol is sufficiently interfacially-active to behave like a surfactant and this has major impact on mass transfer coefficients and hydrodynamic assumptions made for the non-equlibrium model. The concentrations of solute were relatively low and the non-equilibrium model did not indicate any notable degree of interaction of the mass transfer coefficients of the two main solutes. Chemical systems with much higher solute concentrations need to be investigated.

Single drop mass transfer in ternary and quaternary liquid–liquid extraction systems

Population-balances are a powerful method to predict the population behavior of drops in chemical-engineering equipment such as solvent extraction columns. In such columns a complex interaction of different phenomena, namely drop sedimentation, mass transfer, drop breakage and coalescence as well as axial dispersion occurs. In this article the concept of drop-population balances is discussed in detail as well as possible solution methods. Also, a critical review of existing models accounting for breakage and coalescence taking place in extraction columns is presented. Future parts of this series will be devoted to modelling mass-transfer and sedimentation as well as on application of single-drop based modelling.

A Critical Review of the Application of Drop-Population Balances for the Design of Solvent Extraction Columns: I. Concept of Solving Drop-Population Balances and Modelling Breakage and Coalescence

Liquid-liquid extraction in a novel rotor-stator spinning disc extractor

Single drop experiments with liquid test systems: A way of comparing two types of mechanically agitated extraction columns

Single drop experiments have been performed in specific labscales devices in order to determine the laws representative of the basic mechanisms of drop transport and drop break-up. These laws are useful to the complete description of the behaviour of mechanically agitated solvent extraction columns via a drop population balance model and to an objective comparison between two types of column : a pulsed sieve-plate column and a Kuhni column.

H Angelino

Papers

Single drop experiments with liquid test systems: A way of comparing two types of mechanically agitated extraction columns

Drop Transport and Drop Break-up in Liquid-liquid Extraction Columns: Comparison between Kuhni and Pulsed Column