![]() Spray towers . As in gas absorption , dispersion in the continuous phase limits the application of this equipment to cases where only one or two stages are required.įiller towers. The same types of fillers are used for liquid-liquid extraction as for absorption and distillation . It is preferable to use a material that is preferably wet from the continuous phase. Axial dispersion is a major problem in packing columns and HETP is generally higher than in staged devices. Mixers-Settlers . This type of equipment can vary from a single tank, with an agitator, that causes the phases to mix and then they are allowed to settle, to a large horizontal or vertical compartmentalized structure. In general, sedimentation is done in tanks, although centrifuges are sometimes used. However, mixing can be done in different ways, such as by impact in a jet mixer, by shear action when both phases are fed simultaneously in a centrifugal pump, by means of injectors where the flow of one liquid is induced by the other, or either through holes or mixing nozzles. Continuous differential contact extraction:.Ternary equilibrium diagram: equilateral triangular diagram The two phases in equilibrium are linked by a distribution line. The distribution line passes through the mixing point and its ends on the binodal curve indicate the concentration of the two phases in equilibrium (Figure 1).įigure 1. In the systems of interest for liquid-liquid extraction, the two solvents involved are immiscible or partially immiscible with each other. That is, mixing them in the proper proportions can lead to the formation of two phases. Furthermore, the presence of a solute modifies the solubility of one solvent in another. To represent this behavior, and to be able to know if a certain mixture corresponds to one or two phases, the liquid-liquid triangular diagrams present the so-called binodal or solubility curve (Figure 1). A mixture represented by a point above the binodal curve will consist of a single phase. In contrast, a mixture below the binodal curve has two phases. The concentration of the components on the diagram is shown as mole fraction or mass fraction. One of the most common ways of collecting equilibrium data in ternary systems is triangular diagrams. An equilateral triangular diagram is shown in Figure 1. The vertices of the triangle represent pure compounds, a point on one side would correspond to a binary mixture and a point inside the triangle would represent a ternary mixture. The composition of a mixture can be determined by direct reading on the diagram, as shown in Figure 1. In the design of a liquid-liquid extraction operation, it is usually considered that the refining and the extract are in balance. The balance data to be handled will be at least those corresponding to a ternary system (two solvents and one solute), with two of the components immiscible or partially immiscible with each other. Non-toxic, non-flammable, cheap and easily accessible.Low Viscosity, Pv, Freezing Point For Easy Handling.Chemically stable and inert with the other components.High surface tensionto avoid dispersion of the phases.Density differences between the phases that form.Feed composition, temperature, pressure and speed of flow.Obtaining expensive metals, eg uranium– vanadium .Pharmaceutical products Example in obtaining penicillin.In the extraction of products containing sulfur.Refining of lubricating and solvent oils.Separation of inorganic compounds such as phosphoric acid, boric acid and sodium hydroxide.As a substitute for chemical separations.Compounds sensitive to temperature rise.Other methods are not feasible: Similar or very small volatilities.6 Equipment for liquid-liquid extraction.In a liquid-liquid extraction operation, the solution to which the components are intended to be separated is called the liquid extraction solvent to be used to separate the desired component, refined to the feed already treated and extract to the solution with the solute. ![]() The Extraction Liquid -Liquid is, by distillation, the most important basic operation in the separation of homogeneous liquid mixtures. It consists of separating one or several substances dissolved in a solvent by transferring it to another insoluble, or partially insoluble, solvent in the first one. The transfer of matter is achieved through direct contact between the two liquid phases. One of the phases is dispersed in the other to increase the interfacial surface and increase the flow of transferred material.
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