Continuous extraction processes

Attention is directed to the great advantage of continuous extraction over manual shaking in a separatory funnel for liquids or for solutions which tend to froth or which lead to emulsification comparatively little difficulty is experienced in the continuous extraction process. 

The batch process, which tends to be less efficient than the continuous extraction process, involves macerating the tissue with the appropriate solvent in a Waring Blender, soaking for a short time (1), filtering in a suitable size of Buchner funnel and then returning the residue to fresh solvent for further extraction. The combined solvent extracts are then evaporated, usually under reduced pressure and the residue submitted to appropriate fractionation procedures (2). 

The formation of emulsions, suspensions, and cruds at the liquid-liquid interfaces, which disturb the continuous extraction process (84, 101, 102, 107 111). 

Propane fractionation a continuous extraction process employing liquid propane as the solvent a variant of propane deasphalting (q.v.). 

A new apparatus was developed for continuous extraction of contaminated soil material for high pressure (25 MPa) and high temperature (663 K) operating conditions. The extraction of hydrocarbon contaminants from long weathered and highly contaminated soil material could be realised with supercritical water under parallel flow. Within a residence time of only 28 s suspensions of less than 0.75 wt% soil in water could be cleaned (> 90 %). For a concentration of 1 wt% soil in water 43 s were needed to achieve a clean-up result of 98.3 %. The continuous extraction process can be carried out multistage. Then higher concentrated suspensions (2-4 wt%) can be also cleaned by supercritical water extraction. 

Supercritical fluid extraction has been focused for the deterpenation of citrus oil as a lower temperature process [1-6]. Coppella and Barton [4], Stahl and Gerard [5], and Temelli et al. [6] studied the extraction process for the removal of terpenes in citrus oil. However, the simple extraction process does not give sufficient selectivity and yield A continuous countercurrent extraction process is one of the method to achieve higher selectivity between terpenes and oxygenated compounds. Perre et al. [7] and Sato et al. [8] succesfully developed the continuous extraction process. 

Once the large meal particles are separated, the clean miscella is stored in a surge tank, generally referred to as a full miscella tank. The full miscella tank has several purposes It separates the continuous extraction process from the continuous distillation process, it provides miscella storage capacity during a power... 

Chromatography is a continuous extraction process in which solute species are exchanged between two phases. One, the mobile phase, moves with respect to the other, stationary phase. The partition ratio iC of a solute A between the stationary and mobile phases is... 

For a single-stage batch process or a continuous extraction process that achieves one theoretical stage, the solute reduction factor is given... 

Craveiro AC, Lima MB. Bioreactor system with chitosan semipermeable membranes and continuous extraction process, 2000 Brazil Patent Priority CAN 134 177457 AN 2001 164817. 

The flash vessel in the continuous extractive process operates under vacuum, but, in this study, the atmospheric pressure is considered, as no significant changes are expected to occur because of values of the used operating conditions. The classic thermodynamic models require knowledge of binary interaction parameters, which are usually determined from experimental data for binary systems. 

Extraction of organic analytes such as pesticides, PCBs, and fats from solid samples such as food, soil, plants, and similar materials can be done using a Soxhlet extractor. A Soxhlet extractor consists of a round bottom flask fitted with a glass sample/siphon chamber in the neck of the flask. On top of the sample chamber is a standard water-cooled condenser. The solid sample is placed in a cellulose or fiberglass porous holder, called a thimble the solvent is placed in the round bottom flask. Using a heating mantle around the flask, the solvent is vaporized, condensed, and drips or washes back down over the sample. Soluble analytes are extracted and then siphoned back into the round bottom flask. This is a continuous extraction process as long as heat is applied. The extracted analyte concentrates in the round bottom flask. 

Figure 2.5 Illustration of continuous extraction process using a mass separating agent (MSA).

It is convenient to use the Monte Carlo technique based on the quiescence interval technique discussed in this section on steady State continuous systems. For example, consider the continuous extraction process in Section 3.2.4 retaining all the assumptions therein. 

Batch Extractions. In nearly all commercial scale operations, a continuous extraction process, either mixer-settlers or colunm units, would be used. However, batch extraction experiments are useful for assessing overall feasibility and for optimizing the many process variables such as emulsion formulation and volume ratios of the internal, membrane, and external phases. Consequently, the most common experiment in this study was the batch extraction. In these experiments, 500 ml of a selenium solution (1 mg/L) were prepared in the extraction vessel, either in the presence or absence of other competing anions. The prepared emulsion (50 ml) was added and the mixture was stirred at a speed of 150 rpm. In this manner the emulsion drops were uniformly dispersed in the external phase while extraction proceeded. Samples of the external aqueous phase were taken at appropriate intervals and the concentrations of Se(IV), Se(VI), and sulfate were determined. 

Figure 9.2 Continuous extraction process in which product recovery is by two-stage throttling...

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