Filtration gravity filters

Extremely wet solids (solid floating in water). Set up a gravity filtration (see Gravity Filtration ) and filter the liquid off of the solid. Remove the filter paper cone with your solid product, open it up, and leave it to dry. Or remove the solid and dry it on fresh filter paper as above. Use lots of care though. You don t want filter paper fibers trapped in your solid. 

Set up the gravity filtration and filter off the carbon. It is especially important to wash off any product caught on the charcoal, and it is really hard to see anything here. You should take advantage of fluted filter paper. It should give a more efficient filtration. 

Soil solution samples from saturated soils can be obtained by simple filtration. Simple gravity filtration is preferable to vacuum filtration methods because vacuum filtration can lead to distortions in the composition of analyte composition in filtrates. Syringe filters are usually not capable of handling soil and so are not recommended. Also, some filters can retain analytes of interest. 

When shaking is complete, the suspension is gravity filtered through a standard fine filter paper into a sample container. If the filtrate is cloudy, it can be filtered through the same filter paper again. If this is not sufficient, the filter... 

The purple solid is collected by suction filtration and subsequently dissolved in diethyl ether (300 mL), and the resulting dark blue solution is washed with 5 x 200 mL portions of distilled water. The diethyl ether layer is dried over anhydrous MgS04, gravity filtered, and evaporated to dryness on a rotary evaporator. The resulting dark purple/blue crystals are allowed to air dry. Yield 85 g (0.20 mol) of crude Cu(tmhd)2, 75%. 

Five grams of starch-g-polyacrylamide was dispersed in 333 ml of water and the mixture was heated for 4.5 hr at 95-100°C. The cooled dispersion was then treated with ultrasound, as described for starch-g-PAN in DMSO. The resulting solution was gravity-filtered through fluted Whatman 54 paper, and the filtrate was freeze-dried to give 4.4 g of polymer. To give a denser, more compact product, which might more closely resemble soluble starch-g-PAN, the freeze-dried polymer was dispersed in 20 ml of water, and the polymer was precipitated from the thick paste by addition of ethanol. The polymer was separated by filtration, washed with ethanol, and vacuum dried at 60°C. 

Gravity filters are seldom used in the process industries because they offer low filtration rates, however, simple Nutsch filters are sometimes found in the pharmaceutical industry at pilot scale. The Nutsch filter is a tank with a perforated base on which a filter cloth can be supported. The feed slurry liquid filters through the cake and cloth under its own weight. Although these units are low cost, they are labor intensive to operate, cannot be contained for protection of the product or the operator, and are slow. 

The product (0.5 g) is recrystallized by stirring it with acetonitrile (20 mL) for 5 min (or until product has dissolved) and then is gravity-filtered (Whatman no. 1 paper). The filtrate is warmed to about 65°, and water (about 5 mL) is added while the solution is kept warm. Crystals usually appear upon addition of the water, and then the solution is allowed to cool to room temperature and evaporate for 24 hr. Approximate yield is 0.45 g. Anal. Calcd. for C50H48N6O8B2Fe C, 63.99 H, 5.16 N, 8.96. Found C, 63.43 H, 5.12 N, 9.04. 

The heating is discontinued after 24 hours, and the excess sodium metal is removed mechanically. After removal of the sodium, 20 ml. of methanol and then 50 ml. of water are added. The tetrahydrofuran and methanol are removed by vacuum rotary evaporation. The remaining aqueous solution is neutralized and gravity-filtered. The filtrate is treated with a saturated solution of cesium or tetramethylammonium chloride. The crude cesium salt is recrystallized as white plates from hot water in 80% yield based on the C-(trimethyIamine)carbaundec-aborane(12). The tetramethylammonium salt is recrystallized from methanol-acetone. 

A solution of 20 mL of acetic anhydride and 18 mL of 12 N HCl in 50 mL of DMF is added with stirring, and the resulting mixture is gravity filtered through a medium porosity filter paper in order to eliminate the undissolved white solid. After washing the solid with 50 mL of methanol, the clear filtrate is allowed to cool to room temperature. A solution of 15 g (47 mmol) of tetra-butylammonium bromide in 50 mL of methanol is added with rapid stirring, to give a white precipitate. This suspension is stirred for 5 min and the product... 

A 11.46-g (30.00mmol) quantity of bis(l,2-ethanediamine)platinum(II) chloride (Alfa) is dissolved in a minimal amount of water in a SOO-mL Erlenmeyer flask. [The bis(l,2-ethanediamine)platinum(II) chloride must first have been carefully recrystallized twice to insure its purity. Recrystallization is best accomplished by dissolving the solid in SOmL of water, gravity filtering, and allowing the filtrate to evaporate slowly. Pure [Pt(en)2]Cl2 gives a colorless (not brown or yellow) solution when dissolved in water. Impure [Pt(en)2]Cl2 drastically lowers the yield of this procedure.] A 200-mL volume of concentrated HCl is added, and the solution is heated to 89 °C for 7 h. The solution must not be boiled. The reaction mixture is allowed to cool to room temperature, then it is chilled in an ice-water bath. The solid that forms is collected by vacuum filtration, and the filtrate is set aside for platinum recovery. The solid is then washed with lOOmL of water acidified with five drops of concentrated HCl. The product dissolves in this washing, and some insoluble yellow by-product, which is [Pt(en)Cl2], remains on the paper. This second filtrate is treated with 200 mL of concentrated HCl at room temperature, which precipitates the pure product. Yield 4.65 g (30%). 

Membrane filters are used under vacuum, with positive pressure, or with gravity. Filters have been incorporated into certain disposable tips for use with semiautomatic pipettes. These filters minimize the exchange of aerosol droplets between the tips and the pipette. This is of particular importance for DNA amplification and microbiological procedures. Other membrane filters are designed for ultrafiltration and are available with a variety of pore sizes for selective filtration. Ultrafiltration is a technique for removing dissolved particles using an extremely fine filter. It is used to concentrate macromolecules, such as proteins, because smaller dissolved molecules pass through the filter. 

The solutions had been standing for 1 extra day, and Figure 37-13. Proper gravity filtering technique, apparently the precipitate had digested sufficiently more to (Courtesy - Frantz, W., and Malm, L.E. - Chemical increase the overall rate of the filtration when compared to f Table 37-3. 

The next step is to filter out the crystals. A doubled up coffee filter is tight enough to catch almost all of the crystals. A buchner filter is far preferable to any sort of gravity filter. The filtrate should be flushed down the toilet, and the glass container should be immersed in water prior to a more thorough cleaning. 

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