Filtration A method for separating the

Filtration a method for separating the components of a mixture containing a solid and a liquid. 

Cohn and associates had noted that mercuric sulfate gave a precipitate with active fractions, but that both the precipitates and the filtrates regenerated after precipitation by mercuric sulfate always proved inactive. It was believed that the heavy metal precipitated the active substance, but also inactivated it in the process. A method for separating the isoleucine from the active portion (mercuric-sulfate-precipitable) was then sought. Advantage was taken of the fact that the isoleucine is less soluble than the mercuric-sulfate-precipitable portion in the presence of small amounts of alcohol at low temperatures. Thus, treatment of solution (Z) with 11 vol. of alcohol, 6 vol. of ether, and 1 vol. of water resulted in the precipitation of an active material containing no appreciable amount of a-amino nitrogen. 

Distillation and filtration are important methods for separating the components of mixtures. Suppose we had a mixture of sand, salt, and water. Describe how filtration and distillation could be used sequentially to separate this mixture into the three separate components. 

The use of selective seeding as a method for separating solutes in solutions supersaturated with two salts was proposed by Rousseau and O Dell (1980). Supersaturated aqueous solutions of potassium sulphate together with either potassium chloride or dichromate were seeded with one of the solutes to cause secondary nucleation of that substance. After recovering the developed crystals by filtration, the filtrate was seeded with the second solute to complete the separation. 

A method for removing the contaminants in the recycling of PET waste has also been devised. In this process, PET is transesterified by heating with ethylene glycol to give a solution containing short chain PET and bis(2-hydroxyethyl) terephthalate. By hydrolysis of this mixture at elevated pressure and temperature, ethylene glycol and terephthalic acid crystals are produced. Activated carbon and clay are used to absorb contaminants for separation by filtration. ... 

Gel filtration with Sephadex was used by Ghassemi and Christman [426] to make separations by molecular size on water samples concentrated by vacuum evaporation. Fluorescence was also used as one method for following the fractionation. Molecular size was also used by Gjessing [427] but with pressure dialysis as the method of separation. A similar method of concentration and separation was used by Brown [428] to follow the dispersion of these materials as fresh and salt water mixed in the Baltic Sea. 

Treatment of waste should be considered only after source reduction and recycling options are fully addressed. Treatment includes methods for separation of the metals fraction from the wastes stream. This typically involves neutralization, precipitation, filtration and drying operations. Waste treatment, although often desirable and necessary, is not considered to be a waste minimization option by the USEPA... 

Occasionally separating multicomponent solutions requires designing a sequence of fractionators. Henley and Seader [31] discuss some aspects of this problem. Once the sequence has been established, then estimate the size of each fractionator. Table 6.27 lists the equations for a short cut method for calculating the height and diameter of fractionators and Table 6.28 outlines the calculation procedure. Like rotary drum filtration, absorbers, and strippers, discussed earlier, the final design may require testing to support the calculations. 

An extraction is frequently more attractive than a precipitation method for separating inorganic species. The processes of equilibration and separation of phases in a separatory funnel are less tedious and time consuming than conventional precipitation, filtration, and washing. 

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