Countercurrent Liquid-liquid Extraction Research Articles

Jigsaw cooperative learning of multistage counter-current liquid-liquid extraction using Mathcad®

This work shows the improvement in comprehending counter-current liquid-liquid extraction by applying jigsaw-type cooperative learning and the engineering math software Mathcad® in a chemical engineering course, part of the Chemistry degree. This study was performed on two different groups at the University of Almería (Spain) over three academic years. The students were divided into two groups: one half of the class followed a non-cooperative learning methodology (the control) while the other half were spread among the jigsaw cooperative groups following the methodology known as “Jigsaw Experts Groups”. A main template made with Mathcad® of a multistage counter-current liquid-liquid extraction was supplied to both the jigsaw and non-jigsaw groups. The assessment of this educational experience in the course revealed that the jigsaw group outperformed the control group. The use of Mathcad® proved to be very intuitive and effective in explaining these relatively complex problems and utilising it is highly recommended; we suggest it is used rather than classical and less intuitive graphical methods.

Selective Extraction of U(VI) by Counter-Current Liquid-Liquid Extraction with N,N-di(2-Ethylhexyl)-2,2-Dimethylpropanamide

A continuous counter-current extraction experiment for the selective extraction of U(VI) using N,N-di(2-ethylhexyl)-2,2-dimethylpropanamide (DEHDMPA) as an extractant was carried out with mixer-settler type extractors consisting of a U extraction step, a scrub step, and a U back-extraction step. DEHDMPA selectively extracted U(VI) over Pu(IV), and the decontamination factor against Pu(IV) in the U fraction was 990. Fractional distributions of U(VI) in the U fraction and Pu(IV) in the raffinate were 94.5% and 99.9%, respectively. Numerical simulation for calculating U(VI) and Pu(IV) concentrations in each stage of the mixer-settlers was performed. The calculated values agreed with experimentally- measured U(VI) and Pu(IV) concentrations in the U extraction step, and also agreed with the experimentally-measured U(VI) concentrations in the scrub step.

Toward a high yield recovery of antioxidants and purified hydroxytyrosol from olive mill wastewaters.

We investigated to develop effective procedures to recover the potentially high-added-value phenolic compounds contained in the discontinuous three-phase olive processing wastewaters (OMW). Particular emphasis was made to extract and purify hydroxytyrosol, one of the major compounds occurring in OMW. Batch optimization experiments showed that ethyl acetate is the most efficient solvent for the recovery of phenolic monomers from OMW. The latter was used with an optimal pH equal to 2. Furthermore, the percentage of each monomer, and particularly hydroxytyrosol, in the extract was maximum for a solvent ratio and a theoretical extraction stage number equal to 2 and 3, respectively. High yield (85.46%) recovery of hydroxytyrosol was achieved from OMW using a three-staged continuous counter-current liquid-liquid extraction unit. Hydroxytyrosol (1.225 g) were extracted per liter of OMW. One gram of hydroxytyrosol per liter of OMW was then purified by means of a chromatographic system which could be adapted to a large scale production process.

CFD Simulation of Nonideal Dispersed Phase Flow in Stirred Extraction Columns

This paper will focus on hydrodynamic relations arising from single-droplet movement in a rotating disc extraction column (RDC) geometry. These relations can be regarded as the basis for a general estimation strategy for the determination of dispersed-phase flow parameters in connection with droplet population balance modeling. The droplet population balance based modeling of countercurrent liquid-liquid extraction column offers a considerable advance in describing the real droplet swarm behavior. The main problem encountered is the determination of the characteristic droplet model parameters, such as droplet rising velocity, axial backmixing, droplet breakage and droplet coalescence frequencies. The scope of this paper is to estimate fluid and particle residence times and thus the backmixing characteristics.

Modeling, simulation and control of liquid-liquid extraction columns

A model describing the hydrodynamics and mass transfer of countercurrent liquid-liquid extraction columns is developed and solved. The hydrodynamic model assumes that the dispersed-phase drops behave as spheres of uniform diameter. The model has been found to be qualitatively in agreement with experimental results published in the literature. It is shown that conventional dispersion interface level control using the continuous-phase effluent flow rate as the manipulated variable causes unavoidable overshoots and oscillations in the mean holdup and outlet concentrations, while an alternative scheme using the continuous-phase feed flow rate leads to a significant improvement in the dynamic response. A model-based decentralized MIMO control scheme is designed and tested by simulation, and is shown to provide excellent servo and regulatory performance.

Control of a pilot-scale Karr liquid-liquid extraction column

The Karr column is an apparatus for countercurrent liquid-liquid extraction equipped with reciprocating perforated plates. This arrangement improves local mass transfer between the organic and aqueous phases. This system has been reported to be highly nonlinear and potentially difficult to control: most previous studies have involved SISO control for this arrangement with some MIMO exceptions. This paper describes an experimental study which included instrumentation of a Karr extraction column, identification of empirical dynamic models, design of a full matrix (2×2) IMC controller and its implementation on the process using a computer with MATLAB/SIMULINK® as the interface.

Drop size distribution and holdup in a rotating impeller extraction column

A stagewise hydrodynamic model, applying drop population balance equations derived from models for breakage and coalescence of drops in a countercurrent liquid-liquid extraction system, was developed to predict the drop size distribution and the holdup of the dispersed phase in a rotating impeller extraction column. The drop size distributions were obtained by taking the photographs of the dispersions at the same locations through the rectangular shaped glass box filled with distilled water. The experimental variables were the impeller speed and flow rates of the continuous and dispersed phases. The solutions of the model equations were obtained by performing the computer simulation and the optimum parameter values were determined. The results predicted by the model were in good agreement with the experimental results obtained from the present rotating impeller extraction column.

Soil Clean-Up by Surfactant Washing. I. Laboratory Results and Mathematical Modeling

Abstract The removal of weathered-in PCBs from clayey soil by surfactant washing is demonstrated at bench scale. Spent surfactant solution was treated for recycle at bench scale by countercurrent liquid-liquid extraction for the removal of nonvolatile contaminants, and by thin film aeration in packed columns for removal of volatile organics. A correlation of micelle/water partition coefficients with octanol/ water partition coefficients reported earlier by Valsaraj et al. is extended to several additional compounds. Mathematical models for batch–batch, batch–continuous flow, and countercurrent flow surfactant soil washing are described, and the effects of the model parameters are discussed.

Simulation of a pneumatically pulsed liquid-liquid extraction column

The model presented simulates the hydrodynamic operation of a pneumatically pulsed countercurrent liquid-liquid extraction column. A balance on the droplet population is compiled at all levels of the column. This balance, which accounts for transport, rupture and coalescence mechan The experimental results obtained in steady-state conditions on a pilot plant facility served to validate the proposed model. Dynamic simulations of va

SIMULATION OF LIQUID-LIQUID EXTRACTORS

Modelling and simulation of a counter-current liquid-liquid extraction column for removal of benzene from raw hexane using sulfolanc as the solvent is studied. The short-cut method (Smith and Brinkley, 1960; Henley and Seader, 1981) and the rigorous method of isothermal sum rates (Tsuboka and Katayama, 1976) with the UNIFAC method for prediction of activity coefficients are applied to evaluate the composition of benzene in the raffinate. The predictions are compared with pilot plant experimental data on a counter-current sieve-tray extractor for different solvent-to-feed ratios and different number of stages.

Oxidation of Pu(III) by Nitric Acid in Tri-n-Butyl Phosphate Solutions. Part I. Kinetics of the Reaction and Its Effect on Plutonium Losses in Countercurrent Liquid-Liquid Extraction

Oxidation of Pu(III) in tri-n-butyl phosphate solutions containing nitric acid has been studied by ultraviolet/visible spectrophotometry. The concentrations of Pu(IV) and nitrous acid (HNO2), one of the reaction intermediates/products, were monitored. An autocatalytic reaction mechanism is proposed in which a small amount of HNO2 is generated during an induction period. It then catalyzes the reaction by reacting with nitric acid to produce NO2, which oxidizes Pu(III) in the rate-determining step. It is suggested a nitritoplutonium(IV) complex is formed that finally reacts with nitric acid to form more HNO2.Reaction rates, measured under conditions similar to those encountered in a solvent extraction contactor, indicate that the reaction proceeds rapidly at concentrations of HNO3 greater than ~0.2 M in the organic solutions and it is responsible for plutonium losses often observed in solvent extraction operations.

Countercurrent Liquid-Liquid Extraction in Rotating Multiple Helix

Countercurrent Liquid-Liquid Extraction in Rotating Multiple Helix

The application of discontinuous, countercurrent, liquid-liquid extraction to the study of the distribution of metal ions between hydrochloric acid and methyl isobutyl ketone

The extraction of the elements Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Ga, As, Nb, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, La, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb and Bi from hydrochloric acid into methyl isobutyl ketone has been studied as a function of hydrochloric acid concentration. The results are presented in graphical form. The data were obtained by studying the distribution patterns of the elements after equilibration on a Craig countercurrent liquid-liquid extraction apparatus.

Limiting Velocities in Countercurrent Liquid-Liquid Extraction Column Equipped with Stirrers

Experimental studies were made on the limiting flow rate in a countercurrent liquid-1iquid extraction column equipped with stirrers.Two types of operating regions were recognized to be caused by flow rates and stirrer speeds as shown in Fig. 3: the regular and the transition-region.The regular-region was caused in direct proportion by higher stirrer speeds and higher flow rates of continuous phase. The maximum flow rate of dispersed phase was observed when flooding phenomena occurred.The transition-region was caused in inverse proportion by lower stirrer speeds and lower flow rates of continuous phase. The maximum flow rate in this case was observed when inversion of two phases (from the state of oil in water to the state of water in oil) occurred.Experimental data were correlated by plotting the dimensionless groups of (Ud/Uc) vs (Ucμc/σ) (NDND2ρc/μc)0.94 (NDND2ρd/μd)0.10 (NN2D3ρc/σ)-0.53 (NN2D/g)1.51 (Δρ/ρc)-1.90 for flooding velocities, and (Ud /Uc) vs (Ucμc/σ) (NDND2ρc/μc)0.97 (NN2D3ρc/σ)-0.90 (NN2D/g)0.76 (Δρ/ρc)-0.60 for phase inversion velocities as shown in Fig. 9.

Counter Current Liquid-Liquid Extraction Column with Agitators.

Counter Current Liquid-Liquid Extraction Column with Agitators.

Extraction of uranyl nitrate in a disc column

The disc column designed by S tephens and M orris [14] for gas absorption studies has been modified for countercurrent liquid-liquid extraction. The effect of liquor rates on the overall mass transfer coefficients and heights of overall transfer units has been studied for the continuous, countercurrent extraction of an aqueous solution of pure uranyl nitrate. The feed solution contained 0·348 lb. UO 2(NO 3) 2 per lb. of solution and the extractants were uranium-free diethylene glycol di-n-butyl ether (dibutyl carbitol) and methyl iso-butyl ketone, initially containing 0·049 lb. UO 2(NO 3) 2 per lb. of solution. The solvent was the “ dispersed ” phase in each case. The data may be correlated, for the range of liquor rates studied, by the equations : ▪

Separation of the higher monoamino-acids by counter-current liquid-liquid extraction: the amino-acid composition of wool

THE possibility of employing counter-current liquid'liquid-extraction for the separation of amino-acids in the form of acyl derivatives from protein 'hydrolysates was briefly discussed by Synge [1939, 1-4], who described preliminary experiments on the separation of some of the naturally occurring 'monoaminoacids'. In the present paper we review the literature on counter-current liquidliquid extraction, discuss the mathematical and physical basis of the separation of acylamino-acide by liquid-liquid extraction, and describe the construction, operation and testing of a multi-plate chloroform-water counter-current extraction train. We then describe the use of this machine in a control analysis of a known mixture of amino-acids for such components as methionine, valine, proline, the leucines and phenylalanine, together with the application of the new technique to an analysis of wool for these amino-acids. In conclusion we compare the results with those obtained by other methods, and summarize existing knowledge of the amino-acid composition of wool.

Countercurrent Liquid-Liquid Extraction in a Packed Tower

Countercurrent Liquid-Liquid Extraction in a Packed Tower