Centrifugal sieves

The goal of this step is to separate fiber from the starch-fiber cake with an acceptable starch loss. Some small fiber particles may remain in the rough starch. For fiber removal, diluted cake from the potato juice extraction is sieved in so-called centrifugal sieves. This type of sieve consists of a conical rotating sieve with perforations of 125 pm (Figure 11.13). 

AJ Dijkstra, PJ Maes. Separating solid and liquid phases in edible oils by centrifugal sieving or decantation with short residence time. Eur Patent EP 88949, 1983. 

Vibrating screen, horizontal or inclined high-speed low-amplitude vibrating screens sifter screens static sieves centrifugal screens. 

Two-phase suspension systems produce beaded products with broader particle-size distribution (e.g., 1-50 /rm). The microspherical particles usually need to be classified repeatedly to reduce the particle-size distribution in order to improve the resolution and efficiency in the separation for use in chromatography. The actual classification process depends on the size range involved, the nature of the beaded product, and its intended applications. Relatively large (>50 /rm) and mechanically stable particles can be sieved easily in the dry state, whereas small particles are processed more conveniently in the wet state. For very fine particles (<20 /rm), classification is accomplished by wet sedimentation, countflow setting, countflow centrifugation, or air classification. 

Extractors with mechanical agitation, such as mixer-settlers, Kuhni columns, York-Schiebel columns, etc., should be avoided as much as possible. Up to seven theoretical stages packed extraction columns can be conveniently adopted. Sieve-plate extractors can be used up to 20 stages. When a very efficient extraction has to be carried out with expensive solutes, and for reasons of material stability and requirements of low expensive product inventory, we may have to use centrifugal extractors or hollow-fibre extractors. 

Soil Drying of soil sample followed by sieving digestion with HN03 centrifugation ICP/AES 0.09 pg/g 97-103 Schmitt et al. 1988... 

El, E2 El, E2, 17ot-E2, EE2, E3 Cleaning SPE and LC SBSE Centrifugation, lyophilization, grinding, sieving USE Cleanup SPE, derivatization with dansyl chloride, LLE with hexane, silica gel column chromatography... 

Step 1 To an appropriate centrifuge tube add 1-g (0.001-g) of air-dry, sieved soil and 40 mL of acetic acid. The mixture is shaken overnight, centrifuged, and the supernate separated from the residue for analysis. 

A 1-g sample of sieved ( 10 sieve, <2.00 mm) air-dry soil is placed in a 20-mL glass centrifuge tube and 10 mL of dichloromethane (CH2C12) added. The mixture is shaken for between 30 minutes and 1 hour. Extracts are centrifuged to separate the extract from soil before analysis (adapted from Reference 5). 

This method has been applied to bottom sediments and muds [4]. The mud sample is centrifuged to separate the water, dried at room temperature, ground and sieved. This residue is extracted for lh at 80°C with methanol-benzene (1 1), the extraction is repeated twice, and the combined extracts are evaporated and the residue dissolved in water. Alkylbenzenesulphonates are then determined by infrared spectroscopy as described above. 

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