Pad filtration

The method most commonly used to stabilize a wine, once instability is determined, is to chill the wine to -5° C and hold it until stability is achieved, usually seven to fourteen days. Addition of fine potassium bitartrate crystals during chilling (30 mg/L) helps seed the formation of potassium bitartrate crystals. When laboratory tests have shown the wine to be stable, the wine goes through a tight diatomaceous earth or pad filtration to remove the crystals. 

In the discovery laboratory, diol 4 produced by this dihydroxylation method was conveniently converted to 5 via a two-step procedure (Scheme 3.5). " - Oxidative cleavage of 4 by NaI04 (1 equiv) gave dialdehyde 15 in aqueous dichloroethane. Aqueous washes effectively removed NalO, salts, and the extracts were treated with benzylamine (1.05 equiv), dried by filtration through a cotton plug, then added to NaBH(OAc)3 (3.6 equiv). Conversion to 5 was complete within hours. Aqueous workup and silica gel pad filtration of the extracts gave 5 in 82 to 95% yield. 

Often, MF is kept as a final filter for insurance. UF prolongs the life of this filter indefinitely. In spite of DE and pad filtration, MF can clog within 4 to 5 hours without UF. 

The lone pair is thus buried inside a lipophilic hydrocarbon framework, making this material particularly nonpolar. A silica gel pad filtration using the extraction solution of 5 from the reaction workup provided material with the expected low osmiiun levels as determined by ICP-MS (<0.04 ppm). Benzyl group removal by hydrogenolysis of the HCl salt of 5 gave benzazepine 6. 

IMPROVED AND ALTERNATIVE SOURCES OF LIPIDS Table 11.2 Free fatty acids in fryer oil with and without filtercorp pad filtration ... 

Depth filtration systems use either paper pads, diatomaceous earth ( DE or powder ), or a combination of the two media to remove particulates. In the case of pad filtration, particles accumulate at the filter surface and are entrapped within a matrix of narrowing channels and/or retained by charge interactions with the pad. Diatomaceous earth filtration utilizes the same filtration principles as pads (i.e., particle exclusion and... 

Fiber Bed Alist Filtration. In-depth fiber bed filters are used for the collection of Hquid droplets, fogs, and mists. Horizontal pads of knitted metal wire (or plastic fibers), 100—150 mm thick, and gas updow are used for Hquid entrainment removal. Pressure drop is 250—500 Pa (1.9—3.8 mm Hg). 

Panel filters may use either viscous or dry filter media. Viscous filters are so called because the filter medium is coated with a tacky liquid of high viscosity (e.g., mineral oil and adhesives) to retain the dust. The filter pad consists of an assembly of coarse fibers (now usually metal, glass, or plastic). Because the fibers are coarse and the media are highlv porous, resistance to air flow is low and high filtration velocities can be used. 

A pad of Filter-Cel aids in the slow filtration. About 100 g. is needed with a 30-cm. funnel. 

Pads of a mixture of paper pulp and asbestos fiber are used in bacteriological filtrations. In sheet form it is employed in the laboratory for all kinds of filtration. Filter papers are made in many grades of porosity for use in porcelain and glass funnels. Industrially, paper in the form of sheets is used directly or as a precoat in filter presses. 

Effective inlet air filtration is required to ensure satisfactory operation of the engine. The location of the unit determines the most appropriate filter system to use. Desert environments where a large amount of sand particles could be expected in the ambient air may use an automatic roll type of filter that allows new filter material to be rolled in front of the inlet without frequent shut-downs to change filters. Arctic or extremely cold locations may use pad type filters, snow hoods to prevent blockage, and exhaust recirculation to prevent icing. Filter assemblies for offshore marine environments may include weather louvers, demister pads, and barrier elements for salt and dirt removal. Screens may be u.sed for insect removal prior to filtration in areas with bug problems. 

Filtration of the catalyst over a Hyflo pad and removal of the solvent left a yellow crystalline residue. The crude mixture of ketone and potassium acetate was partitioned between methylene chloride (300 cc) and water (1 liter), The layers were separated and the water layer washed with methylene chloride (3 x 50 cc). The organic layers were combined, washed with 3N sodium hydroxide solution (2 x 50 cc), water (3 x 100 cc), dried over anhydrous sodium sulfate and filtered. The solvent was removed and the product recrystallized from ethanol to give 2-amino-2 -fluorobenzophenone as yellow prisms melting at 126° to 128°C,... 

A mixture of 10 mmol of the allyl bromide and 10-15 mmol of the aldehyde, dissolved in 20 mL of THF, is added dropwise at — 5 to 0°C to the chromium(II) chloride solution in THF prepared by method A or B. The mixture is stirred for 36 h at this temperature and then 15 mL of sat. sodium hydroxide and 20 g of anhyd Na2S04 are added stirring is continued for 20 min at 201C. The mixture is filtered over a pad of Celite/Na2S04 (7 l). The filtrate is concentrated and the residue purified, usually by chromatography on silica gel with pentane/diethyl ether or hexane/ethyl acetate. 

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