Mechanical extraction development

Van der Linden, Wassink and Theusink, have recently reported on a novel technique for mechanically extracting water though the use of a pressure differential across fabrics which is on the order of 0.5 atmospheres (6). The pressure differential is developed by either throttling high pressure steam (6 atm.) or compressed air through a one-mil wide nozzle (Machnozzle). Steam is usually employed since the nozzle operates isoenthaipically,... 

Today, continuous screw-presses dominate the mechanical extraction of fats. The only applications still favoring hydraulic presses are those requiring gentle handling, for example, pressing cocoa butter from cocoa beans where the defatted residue is to be fine-ground to make cocoa powder. The development of continuous screw-presses will be outlined in Section 4.2. The development and technology of hydraulic presses was covered in detail in previous editions of this book (109). This edition briefly summarizes the early development of hydraulic presses and then focuses on modern, continuous cocoa butter hydraulic presses used today. 

Octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) is one of the representative extractants developed for the separation and recovery of actinides in the nuclear industry. Nakashima et al. investigated the extraction behavior of trivalent rare-earth metals with CMPO using ILs as an extracting phase and demonstrated that not only the extraction efficiency but also the mutual selectivity was remarkably enhanced, in comparison with that in n-dodecane [8]. Although such advantages were observed in the extraction step, the stripping of the metal ions from the extracting IL phase was difficult due to the unique extraction mechanism in the IL system as follows ... 

In a 250 ml. conical flask mix a solution of 14 g. of sodium hydroxide in 40 ml. of water and 21 g. (20 ml.) of pure benzaldehyde (Section IV,115). Add 15 g. of hydroxylamine hydrochloride in small portions, and shake the mixture continually (mechanical stirring may be employed with advantage). Some heat is developed and the benzaldehyde eventually disappears. Upon coohiig, a crystalline mass of the sodium derivative separates out. Add sufficient water to form a clear solution, and pass carbon dioxide into the solution until saturated. A colourless emulsion of the a or syn-aldoxime separates. Extract the oxime with ether, dry the extract over anhydrous magnesium or sodium sulphate, and remove the ether on a water bath. Distil the residue under diminished pressure (Fig. 11,20, 1). Collect the pure syn-benzaldoxime (a-benzald-oxime) at 122-124°/12 mm. this gradually solidifies on cooling in ice and melts at 35°. The yield is 12 g. 

Mechanical Pressing. Historically, the first large commercial production of oils from seeds and nuts was carried out using labor-intensive hydraulic presses. These were gradually replaced by more efficient mechanical and screw presses. Solvent extraction was developed for extraction of seeds having low oil content. For seeds and nuts having higher oil content, a combination of a screw press followed by solvent extraction is a common commercial practice (prepress—solvent extraction). 

The development of a suitable solvent system is important for successful operation. Solvent systems generally consist of at least the following components extractant, diluent, inorganic salts or acids, and water. The relative optimization of these components yields the best conditions with which to achieve separation. A key factor to success is the choice of the appropriate extractant. Many extractants may be used for REE separation. These may be divided into three groups on the basis of the mechanisms involved. These extractants are tisted in Table 7. 

The treatments used to recover nickel from its sulfide and lateritic ores differ considerably because of the differing physical characteristics of the two ore types. The sulfide ores, in which the nickel, iron, and copper occur in a physical mixture as distinct minerals, are amenable to initial concentration by mechanical methods, eg, flotation (qv) and magnetic separation (see SEPARATION,MAGNETIC). The lateritic ores are not susceptible to these physical processes of beneficiation, and chemical means must be used to extract the nickel. The nickel concentration processes that have been developed are not as effective for the lateritic ores as for the sulfide ores (see also Metallurgy, extractive Minerals recovery and processing). 

Experimental evidence in humans is based upon intervention studies with diets enriched in carotenoids or carotenoid-contaiifing foods. Oxidative stress biomarkers are measured in plasma or urine. The inhibition of low density lipoprotein (LDL) oxidation has been posmlated as one mechanism by which antioxidants may prevent the development of atherosclerosis. Since carotenoids are transported mainly via LDL in blood, testing the susceptibility of carotenoid-loaded LDL to oxidation is a common method of evaluating the antioxidant activities of carotenoids in vivo. This type of smdy is more precisely of the ex vivo type because LDLs are extracted from plasma in order to be tested in vitro for oxidative sensitivity after the subjects are given a special diet. 

Fluoro-2 -deoxyuridine has been extensively used in studies of the mechanism of action of thymidylate synthase, and 5-fluorouracil is an anticancer drug that has provided a lead to the development of others. The metabolism of 5-fluorouracil by the ascomycete fungus Nectria haematococca has been studied using F NMR (Parisot et al. 1991). a-Fluoro-P-alanine (2-fluoro-3-aminopropionate) was produced (Figure 10.27), while 5-fluorouridine-5 -mono-, di-, and triphosphate were found in acid extracts of the mycelia, and the 2 - and 3 -monophosphates were recovered from RNA. 

Organic solvent extraction. Two analytical methods for acetamiprid have been developed One method is for the parent only and the other determines the total residue of the parent and its metabolites (lM-1-2, lM-1-4 and lC-0). Air-dried soil (20-g equivalent dry soil) is weighed into a centrifuge tube and imidacloprid residue is extracted with 100 mL of methanol-0.1M ammonium chloride (4 1, v/v) using a mechanical shaker for about 30 min. After shaking, the tube is centrifuged at 8000 rpm for 2 min. The supernatant is filtered and the analysis of the soil residue is carried out in the same manner as described above for the parent compound. 

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