Liquid filtration vacuum process filters

You know how just a couple of paragraphs ago where the chemist first filtered the crude crystals from the chilled reaction mixture, then washed them with water or acetic acid Well, all that liquid filtrate has a lot of valuable, unreacted piperonal or benzaldehyde in it. To rescue the stuff the chemist dilutes the mixture with 500ml dHaO and extracts it with DCM. The DCM is washed with 100ml 5% NaOH solution then vacuum distilled to give a dark oil which is unreacted aldehyde. Hey That s a lot of good material that can be put through the process again. 

Rotary Drum Vacuum Filter The underflow from the thickener is the feed to this filter. The filter concentrates the solids (predominately calcium sulfite), which then leave the filter in a cake form and are transferred to a cake repulp tank where they can be reslurried. The liquid generated from the filtering process (filtrate) is collected and pumped to the lime reactor vessel. 

Solvent-Refined Coal Process. In the 1920s the anthracene oil fraction recovered from pyrolysis, or coking, of coal was utilized to extract 35—40% of bituminous coals at low pressures for the purpose of manufacturing low cost newspaper inks (113). Tetralin was found to have higher solvent power for coals, and the I. G. Farben Pott-Broche process (114) was developed, wherein a mixture of cresol and tetralin was used to dissolve ca 75% of brown coals at 13.8 MPa (2000 psi) and 427°C. The extract was filtered, and the filtrate vacuum distilled. The overhead was distilled a second time at atmospheric pressure to separate solvent, which was recycled to extraction, and a heavier liquid, which was sent to hydrogenation. The bottoms product from vacuum distillation, or solvent-extracted coal, was carbonized to produce electrode carbon. Filter cake from the filters was coked in rotary kilns for tar and oil recovery. A variety of liquid products were obtained from the solvent extraction-hydrogenation system (113). A similar process was employed in Japan during Wodd War II to produce electrode coke, asphalt (qv), and carbonized fuel briquettes (115). 

Filtration. The process hy which suspended sohd particles are removed from hquid is called filtration. The hquid containing suspended sohd particles is passed through a porous medium. A clear hquid is obtained. The porous medium may be a fabric, a canvas, a paper, a screen, or a bed of sand. For small particles a filter with very small pores is used but for larger particles sand may be used. The liquid flow may be passed through the filter under the influence of gravity, positive pressure, or vacuum. The use of medium depends upon the size of the sohd particle. 

Pressure filtration differs fi-om vacuum filtration in that the liquid is forced through the filter medium by a positive pressure instead of a vacuum. Among the most widely used in Che chemical process industry (and widely used in Europe for wastewater treatment) is Che filter press. As shown in Figure 3, Che filter press operates by pumping the sludge between plates that are covered with a filter cloth. The liquid seeps throu Che filter cloth leaving the solids bdiind between the plates. Whoi the spaces between the plates are filled, the treatment plant operator separates the plates and removes the solids. 

Set up a 50-mm Buchner funnel for vacuum filtration using a 125-mL filter flask. Filter the mixture through a piece of Whatman 2 filter paper (4.25 cm). The filtration process may be slow. You can push the solid down a bit with a bent spatula to remove as much of the liquid as possible. Keep the filtrate, and add another 5 mL of 3 M aqueous HCl to the filtrate in the filter flask. The second addition of HCl produces more solid, but not as much as what you obtained after the first addition of HCl. Set up another vacuum filtration apparatus using your partner s 125-mL filter flask and 50-mm Buchner funnel. Refilter the mixture through a fresh piece of filter paper. Discard the solids that you collected on the filter papers. Remember you want to keep the filtrates. Combine the tivo batches of filtrates. The filtrate consists of the product dissolved in toluene and the aqueous layer. 

At the end of Section 7.2.1, the process of rotary vacuum filtration is described. Here the membrane containing the particulate cake/deposit (see Figure 6.3.25(a)) is moved perpendicular to the pressure induced crossflow causing filtration through the filter. If we imagine the coordinate system to be fixed to the membrane, then the system configuration is similar to the crossflow microfiltration briefly considered earlier (Figure 6.3.25(b)) where the liquid slurry/suspension moves parallel to the membrane but perpendicular to the direction of the force. 

Gas-tight vacuum belt filters are a valuable development in belt filtration technology. They are required where the solid materials or liquids involved in the process give off fumes, which may be toxic or chemically explosive and/or just create... 

In conclusion, the following experiments on filtration-washing-deliquoring should be performed to produce data (viscosity of liquids, effective solid concentration, specific cake resistance, cake compressibility, etc.) that are necessary to evaluate times of individual steps of filtration at an industrial scale, i.e. to obtain the proper basis for scale-up of filtration processes measure the filtrate volume versus time make marks on your vacuum flask and take down the time when the filtrate level reaches the mark => no more experiments are needed for preliminary evaluations of filtration properties of slurries initially fines pass the filter medium => recirculate them to the slurry,... 

Pharmaceutical Removal of suspended matter is a frequent application for MF. Processes may be either clarification, in which the main product is a clarified liquid, or solids recovery. Separating cells or their fragments from broth is the most common application. Clarification of the broth in preparation for product recovery is the usual objective, but the primary goal may be recovery of cells. Cross-flow microfiltration competes w l with centrifugation, conventional filtration by rotary vacuum filter or filter press and decantation. MF delivers a cleaner permeate, an uncontaminated, concentrated cell product... 

The above process is repeated ten times, the broths obtained are combined, the pH is adjusted to 6, the combined broths are filtered, and the resulting filtrate is extracted countercurrently at the rate of 128 gallons per hour with about the same rate of butanol, in a 12" diameter by 11 ft. high Karr extraction column. A water backwash of 0.2 times the butanol rate is employed at the top of the extraction column to minimize the carry-over of water soluble components. The butanol extract is concentrated to approximately a 5% solution which comprises the feed to the center of a 3" diameter by 20 ft. high Karr fractional liquid extraction column. This column is operated at a water to butanol ratio of about 10 to 1, and the butanol extract contains the product. The butanol extract is concentrated by evaporation to a solution or paste containing about 5 to about 20% ent solids then about 25 to about 50 volumes of n-hexane are added, and the resulting slurry filtered. The precipitated product is then vacuum-dried to give a solid compound. 

As an alternative method of procedure, the following may be substituted for Steps 4 to 7 inclusive of the above process. After distilling the benzol, the tarry mass may be stirred directly with 2000 mL of hot 0.3 N NaOH with a mechanical stirrer. The suspension is chilled and the supernatant Liquid poured or siphoned off. Repetition of the extraction two or three times is advisable. The alkaline aqueous solution is then extracted five or six times with 400 mL portions of sulfuric ether, thus transferring the hormone to ether solution. After distillation of the ether the residue is steam distilled as long as a distillate other than water is obtained. The condensed water is removed by vacuum distillation and the small amount of dark tarry residue leached 5 times with 50 mL of hot 0.3 N NaOH. This solution is filtered and the filtrate extracted with sulfuric ether (100 mL, 6 times). The ether solution is distilled and the residue leached with cold 0.3 N NaOH using 20 mL five times. This alkaline solution is filtered and extracted with 50 mL of sulfuric ether five times. Upon distillation of the ether and solution of the residue in a small quantity of hot ethyl alcohol, the hormone separates in semi-crystalline balls which may be filtered off. A further quantity is obtained by adding 3 volumes of water to the alcoholic solution. It may be recrystallized from 25% aqueous ethyl alcohol or from 25% aqueous acetone or from any of the following chloroform, benzol, ethyl acetate, ethyl ether or petroleum ether. The final product consists of colorless crystals which, when crystallized from dilute alcohol, possess a distinct rhomboid outline. The crystals melt at 242-243°C (248-249°C corrected) with some decomposition. 

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