Extraction batch

For a linear equilibrium curve with constant film coefficients, kL and kG, the overall coefficient, KL, will also be constant, but for the case of a non-linear equilibrium relationship, the value of m, which is the local slope of the equilibrium curve, will vary with solute concentration. The result is that the overall coefficient, KL, will also vary with concentration, and therefore in modelling the case of a non-linear equilibrium extraction, further functional relationships relating the mass transfer coefficient to concentration will be required, such that 

Two solutes distribute themselves between the two phases as concentrations XA and Ya, and XB and YB and with rates QA and QB, respectively, as shown in Fig. 3.28. The corresponding equilibrium concentrations XA and XB are functions of both the interacting solute concentrations, YA and YB, and can be expressed by functional relationships of the form 

Typical representations of the way that the two differing equilibrium relationships can interact are shown in Fig. 3.29, and it is assumed that the equilibria can be correlated by appropriate, explicit equation forms. 

For multi-component systems, it is necessary to write the dynamic equation for each phase and for each solute, in turn. Thus, for phase volume VL, the balances for solute A and for solute B are 

The overall mass transfer coefficients are also likely to vary with concentration, owing to the complex multisolute equilibria, such that 

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Interfacial Mass-Transfer Coefficients. Whereas equiHbrium relationships are important in determining the ultimate degree of extraction attainable, in practice the rate of extraction is of equal importance. EquiHbrium is approached asymptotically with increasing contact time in a batch extraction. In continuous extractors the approach to equiHbrium is determined primarily by the residence time, defined as the volume of the phase contact region divided by the volume flow rate of the phases. 

The pot extractor is a batch extraction plant in which extraction and solvent recovery from the exhausted soHds can be carried out in a single vessel. These extractors are normally agitated vessels having capacities in the range of 2 to 10 m, beyond which the battery system becomes a preferred technical alternative. 

Hixson and Smith [Ind. Eng. Chem., 41, 973 (1949)]. Batch extraction of iodine from water into carhon tetrachloride iinhaffled vessels, propeller agitated. Log (1 — ) is hnear with time. 

Batch extraction of octanoic acid from water and corn syrup into xylene, paraffin oil, and their mixtures baffled vessel, turbine impeller. proportional to... 

It has been found that this data can be correlated for batch extraction using the following correlation ... 

In routine analysis batch extraction appears to be still the method of choice. However, developing alternative flow-through schemes for comprehensive studies on the fractionation and mobility of TE in environmental solids looks rather promising. 

Sodium thiocyanate has also been recrystd from water, acetonitrile or from MeOH using Et20 for washing, then dried at 130°, or dried under vacuum at 60° for 2 days. [Strasser et al. J Am Chem Soc 107 789 1985 Szezygiel et al. J Am Chem Soc 91 1252 1987.] (The latter purification removes material reacting with iodine.) Sodium thiocyanate solns can be freed from traces of iron by repeated batch extractions with Et20. 

Cytochalasin B (from dehydrated mould matter) [14930-96-2] M 479.6. Purified by MeOH extraction, reverse phase Cl8 silica gel batch extraction, selective elution with 1 1 v/v hexane/tetrahydrofuran, crystn, subjected to TLC and recrystallised [Lipski et al. Aruil Biochem 161 332 1987]. 

Lactoferrin (from human whey). Purified by direct adsorption on cellulose phosphate by batch extraction, then eluted by a stepped salt and pH gradient. [Foley and Bates Anal Biochem 162 296 1987.]... 

Figure 2.16 Clirotnatograms of a pentane extract of a water sample containing 200 ppb of a naphtha fraction (a) sample extracted by using a continuous flow system, where a pressurized bottle was employed as the sample-delivery system (b) batch-extracted sample. Reprinted from Journal of Chromatography, A 330, J. Roeraade, Automated monitoring of organic Race components in water. I. Continuous flow exti action together with on-line capillary gas cliro-matography , pp. 263 - 274, copyrigth 1985, with permission from Elsevier Science.

A prehminary study of the use of larch AGs in aqueous two-phase systems [394] revealed that this polysaccharide provides a low-cost alternative to fractionated dextrans for use in aqueous two-phase, two-polymer systems with polyethylene glycol (PEG). The narrow molecular-weight distribution (Mw/Mn of 1-2) and low viscosity at high concentration of AG can be exploited for reproducible separations of proteins under a variety of conditions. The AG/PEG systems were used with success for batch extractive bioconversions of cornstarch to cyclodextrin and glucose. 

SEE extraction pressures of 500 bar at 80 to lOO C combined with countercurrent cascading mode of extraction using four extraction vessels, the rate of oleoresin extraction doubles again rate of oleoresin extraction under these conditions is four times that of traditional batch extraction at 300 bar and 60°C... 

For batch extraction, with no feed into the system, the component balances on each phase are given by ... 

Figure 3.30. Single-solute batch extraction between immiscible liquid phases.

Figure 3.31. Information flow diagram for simple batch extraction.

Again, these functional relationships should ideally be available in an explicit form in order to ease the numerical method of solution. Two-solute batch extraction is covered in the simulation example TWOEX. 

TWOEX - Two-Solute Batch Extraction with Interacting Equilibria... 

COMPLEX TWO-SOLUTE BATCH EXTRACTION WITH INTERACTING EQUILIBRIA... 

Dynantics of Heat Exchangers, Simple Batch Extraction, Multi-Solute Batch Extraction, Multistage Countercurrent Ctiscade, Extraction Cascade with Backmixing, Countercurrent Extraction Cascade with Reaction, Absorption with Chemical Reaction, Membrane Transfer Processes... 

Some of the earliest attempts to address the difficulties associated with making kinetic measurements at immiscible liquid-liquid interfaces were made by Lewis [16,17] using the stirred cell design illustrated in Fig. 2. The Lewis cell employs direct contact between the two immiscible liquids, and reaction rates are evaluated by measuring concentration changes in the bulk of one of the two phases, usually by a batch extraction technique. The rate of change of concentration, dc/dt, is related to the interfacial reaction flux, 7, by... 

James, S. and Bennett, H. P. J., Use of reversed-phase and ion-exchange batch extraction in the purification of bovine pituitary peptides, /. Chromatogr., 326, 329, 1985. 

When the samples were returned to the laboratory the pH was adjusted to approximately pH 8 using concentrated ammonia (Ultrapure, G. Frederick Smith). Chelating cation exchange resin in the ammonia form (20 ml Chelex 100,100 - 200 mesh, Bio-Rad) was added to the samples and they were batch extracted on a shaker table for 36 hours. The resin was decanted into columns, and the manganese eluted using 2N nitric acid [129]. The eluant was then analysed by graphite furnace atomic absorption spectrophotometry. Replicate analyses of samples indicate a precision of about 5%. 

Separating funnels for batch extraction special glass apparatus for continuous extraction automatic shakers used for discontinuous counter-current distribution. 

Batch extraction is the simplest and most useful method, the two phases being shaken together in a separatory funnel until equilibrium is reached and then allowed to separate into two layers. If the distribution ratio is large, a solute may be transferred essentially quantitatively in one extraction, otherwise several may be necessary. The optimum conditions for quantitative extraction have been discussed on p. 57. If several extractions are required, it is advantageous to use a solvent more dense than water, e.g. carbon tetrachloride or chloroform, so that the aqueous phase can be left in the separatory funnel until the procedure is complete. 

Batch esterification, 10 478—480 Batch experimental reactor, 21 352 Batch extraction, 10 756 Batch extractor, holdup in, 10 764 Batch fermentation, 10 267 Batch filter cycles, 11 344, 345-346 Batch furnaces, 12 288—289 Batch gasoline blending, 12 413 Batch hydrogenation, 10 811 Batching, ceramics processing, 5 648 Batch injection analysis (BLA) technique, 9 586-587... 

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