Centrifugation three phase system

The crushed olives are mixed with water. A horizontal centrifuge separates the mass into pomace and must and the latter is further separated into oil and water 

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New applications and novel reactor configurations or operational modes for three-phase systems are continually being reported. These include the operation of a three-phase fluidized bed in a circulatory mode (Liang et al., 1995), similar to the commonly applied gas-solid circulating fluidized bed the application of a three-phase fluidized bed electrode that can be used as a fuel cell (Tanaka et al., 1990) magnetically stabilized three-phase fluidized beds centrifugal three-phase reactors and airlift reactors. 

Though the term "slurry refers to a suspension of fine solid particles in a liquid, the term slurry reactor is often used for a three-phase system, where both gas bubbles and solid particles are suspended in a liquid phase. For a solid/liquid/gas process, slurry reactors have two obvious advantages the possibilities for very large solid/liquid surface areas and for good heat transfer to the reactor wall. Therefore the volumetric capacity of slurry reactors can be relatively large. However, effective separation of the fine catalyst from the liquid phase may offer considerable technical problems. One possibility is an external separation, e.g. with centrifuges or hydrocyclones, and a transport of a concentrated catalyst slurry back into the reactor. More often internal filters are used, usually consisting of porous tubes (sintered stainless steel, or ceramics), that are cleaned every few minutes by a periodic reversal of the flow. 

Figure 9.2 Flow sheet for olive extraction in a three phase centrifugal system.

The content of polyphenols depends on the extraction system. Pressure systems and two-phase decanters yield oil with a higher polyphenol content and longer induction periods. In the three-phase centrifugal systems the paste is thinned with water and part of the phenols is lost in the water (Di Giovacchino 1996). 

Isolation of Product. Work up the reaction by adding 1.0 mL of a 25% aqueous NaOH solution (calibrated Pasteur pipet), and then transfer the resulting mixture to a 12-mL centrifuge tube using a Fhsteur filter pipet. Rinse the reaction flask with three 2.0-mL portions of diethyl ether. Transfer each rinse to the same centrifuge tube. Partially neutralize the resulting two-phase system by the careful addition of 2.0 mL of 0.1 N HQ and mix briefly. 

Olive oil is nowadays produced by either two or three-phase extraction systems. The three phase method in which a solid fraction (wet pomace or alperujo), a liquid residue ( alpechin ), and the olive oil are obtained. Two phase method in which a solid fraction, wet pomace and a liquid one, the olive oil, are obtained. The main advantage of the two-phase system is the reduction of the olive mill wastewater amoimts compared to that originated from the three phase technology, in which 0.6-1.31 water/kg olives are used at the centrifugation step, by eliminating the production of alpechin thus avoiding its consequences environmental... 

Bergstrom et al. [63] used HPLC for determination of penicillamine in body fluids. Proteins were precipitated from plasma and hemolyzed blood with trichloroacetic acid and metaphosphoric acid, respectively, and, after centrifugation, the supernatant solution was injected into the HPLC system via a 20-pL loop valve. Urine samples were directly injected after dilution with 0.4 M citric acid. Two columns (5 cm x 0.41 cm and 30 cm x 0.41 cm) packed with Zipax SCX (30 pm) were used as the guard and analytical columns, respectively. The mobile phase (2.5 mL/min) was deoxygenated 0.03 M citric acid-0.01 M Na2HP04 buffer, and use was made of an electrochemical detector equipped with a three-electrode thin-layer cell. The method was selective and sensitive for mercapto-compounds. Recoveries of penicillamine averaged 101% from plasma and 107% from urine, with coefficients of variation equal to 3.68 and 4.25%, respectively. The limits of detection for penicillamine were 0.5 pm and 3 pm in plasma and in urine, respectively. This method is selective and sensitive for sulfhydryl compounds. 

CPCs for separation of proteins which are not soluble in the PEG-phosphate system. This two-phase solvent system consists of the PEG-rich upper phase and dex-tran-rich lower phase. The cross-axis CPC may be operated in four different elution modes PiHO, PuTO, PiTI, and PnHI. The parameters Pi and Pn indicate the direction of the planetary motion where Pj indicates counterclockwise and Pn clockwise when observed from the top of the centrifuge. H and T indicate the head-tail elution mode, and O and I the inward-outward elution mode along the holder axis. In mode I (inward), the mobile phase is eluted against the laterally acting centrifugal force, and in mode O (outward), this flow direction is reversed. These three parameters yield a total of four combinations for the left-handed coils. Among these elution modes, the inward-outward elution mode plays the most important role in the stationary-phase retention for the polymer-phase sys-... 

Thus, the various treatments of the samples resulted in true equilibrium in them, which was not disturbed by the centrifugation. (However, in some parts of the system the equilibria were influenced by the centrifugation under extreme conditions.) Separation into two or three layers by centrifugation must therefore be regarded as proof that the samples are in a state of heterogeneous equilibrium. The composition and properties of the layers give the composition and properties of the respective phases which are in equilibrium. 

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