Filters and Purifiers

A filter will remove particles from a gas without changing the chemical composition of that gas. A purifier on the other hand, will remove chemical impurities from a gas. In many semiconductor processes these impurities are water vapor, oxygen, and hydrocarbon gases. Both filters and purifiers may be difficult to purge adequately so extra purging my be necessary for their safe use. 

There are many different types of filters available having either porous metal, plastic, or ceramic filter elements. Some filter housings are designed to withstand full cylinder pressure, but some have lower pressure ratings, so care must be taken not to overpressiuize the housing, as sometimes this is the system component having the lowest burst pressure. 

Some in-line purifiers also have low burst pressures so attention should always be given to pressure ratings and appropriate relief devices 

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A suspension of hydroxyboron 2,9,16-triiodosubphthalocyaninc (208mg. 0.26 mmol) and Et3SiOH (1.7 mL) in PhCl (13 mL) was heated at reflux for 2.5 h. The precipitate obtained was filtered and purified by column chromatography (silica gel, EtOAc/hexane 10 1) yield 119 mg (50%). 

A different concept is the idea of manufacturing at point of use rather than transporting materials. A simple and familiar example is the office water cooler. The majority that you see around use large bottles of water. These need to be transported and stored and the empty bottles recycled. More than 600 kT of bottled water were imported into the UK in 1999, creating a significant transport impact. The alternative is to chill and filter mains water on-site. The water needs to be filtered and purified to meet consumer perceptions and expectations. These systems use a mixture of purification techniques including advanced filters, UV-disinfection and silver-treated surfaces to give users the confidence they require. 

Acetylated m-cresol novolac copolymers were prepared by acetylation of m-cresol novolac with acetic anhydride in the presence of sodium hydroxide. The following acetylation procedure is typical. 3.2g of sodium hydroxide (50 mmol) was added to 4.8g of cresol novolac (40mmol) in 10 ml. of water. The reaction mixture was stirred for 10 mins, until all polymer went into solution. The required amount of acetic anhydride was then added, the reaction mixture was stirred for 10 more mins, and poured in 150 ml. of iced water. The polymer was filtered and purified by reprecipitation from a chloroform/benzene (5 2 v/v) solution by the addition of hexane. The acetylation content was determined by H and 13C NMR. 

U,h -Piazidodiphenyl 5G of, l+ -diaminodiphenyl was dispersed in 200ml of 10 hydrochloric acid and 1.5g of sodium nitrite in 10ml of water was added drop by drop with stirring under 5°C. After reacting it for 30 minutes, the solution became transparent. 1.5G of sodium azide was added to this solution gradually. U,U -Di-azidodiphenyl was precipitated. The precipitate was dried at room temperature after filteration, and purified by recrystallizing from methanol. 

HPLC. The crude product was dissolved in 0.1% aq TFA (10 mL), filtered, and purified by preparative HPLC [Preppak, Cartridge YMC ODS column (4.8 x 30 cm), gradient elution MeCN/0.1% TFA/H20 from 20 to 50% MeCN in 90 min (flow rate of 50mL-min-1)]. The fractions containing pure product were combined, concentrated, and lyophilized yield 22.4mg (44%) the peptide was characterized by HPLC (purity 98%), amino acid analysis, and FAB-MS. 

A reactor was charged with the step 4 product (0.96 g), 2,2 -bipyridyl (0.55 g), and THF (80 g). After deaeration, bis(l,5-cyclooctadiene)nickel(0) (1.05 g) was added and the mixture heated to 60°C for 1.5 hours and then cooled and precipitated in 300 ml of ion exchange water. The precipitate was isolated and then dissolved in chloroform, filtered, and purified by passing through a column filled with alumina. The polymer was reprecipitated in methanol, reisolated, dried, and 0.5 g of product isolated having an Mn of 7.3 x 10s Da. 

To 3 mL of immune and preimmune antisera of immunized and non-immunized New Zealand white rabbits, respectively, add a saturated solution of ammonium sulfate dropwise at 4°C to obtain a 45% saturated solution. Separate the supernatant after 4h from the solid by centrifugation (4000 x g, 10 min). Dissolve the solid in 1.5 mL of PBS and dialyze against PBS 0.5 mM (4 x 5 L) and Milli-Q water (1 x 5 L) at 6°C. Filtrate a solution of the antibodies in PBS 20 mM by passing them through a 0.45 pm filter and purify with a HiTrap Protein A HP column. Finally, dialyze and lyophilize the antibodies as above described. 10 mg of pure antibody is obtained. 

A solution of chiral host and racemic guest compounds in an appropriate solvent is kept at room temperature until inclusion complex crystallizes out. In the complexation, it is necessary to use a solvent which does not form inclusion complex with the host compound. The inclusion complex formed is filtered and purified by recrystallization from solvent, if necessary. Host guest molar ratio is... 

The aqueous solution containing 3 -deoxykanamycin B in free base form by addition of concentrated sulfuric acid give the 3 -deoxykanamycin B sulfate (tobramycin sulfate). The solution of this compound is decolorized by stirring of Darco G-60, filtered and purified by column chromatography. 

The second stage, the amidation of chloromethyltriethoxysilane with hexamethylenediamine solution in toluene is conducted at 90-120 °C for 3.5-5 hours. The l-aminohexamethylene-6-aminomethyltriethoxysilane (raw AHM-3) formed is filtered in the nutsch filter and purified from the cake of hydrogen chloride hexamethylenediamine. Then toluene is distilled from raw AHM-3. Toluene is distilled in vacuum (P 52+160 GPa) up to 145 °C (liquid). The distillation is considered complete when the density of the product ranges from 0.945 to -0.965 g/cm3 and no20 =1.440-1.446. The prepared product, l-aminohexamethylene-6-... 

The cyanide solution is ftuther filtered and purified, and gold can then be precipitated with zinc (equation (11)). 

The cnjda 3 (10 g, 0.0325 moO was heated in pyridine hydrochlonde for 30 min Tha cooled mixture was stirred with water, the product was filtered and purified via its sodium salt (NaOH then precipitation with HOAc). Recrystallization from aqueous EtOH afforded 6 g of 4 (87%), mp... 

Crystalline precipitates are generally more easily filtered and purified than are coagulated colloids. In addition, the size of individual crystalline particles, and thus their filterability, can be controlled to a degree. 

For 10 years, this elegant restaurant located in the Santa Monica shopping district has stayed current on health trends. Their meals are high in fiber and low in fat, contain no cholesterol, and have a hearty protein base. They use only organically grown produce and whole foods, and use no animal or dairy products, eggs, sugar, honey, artificial sweeteners, or refined flour. And they even filter and purify their water. 

The direct extraction using different solvents is a more rapid alternative than the distillation for determination of A-nitrosamines in soils. The soil, altogether with suitable nitrosation inhibitors such as ascorbic acid and tocopherol, is homogenized with a suitable extraction solvent. The solvent is then filtered and purified prior to the analysis. You et al. extracted 100 g of soil with a 50 ml portion of DCM during 20 min. The samples were then filtered to remove insoluble particulates. Afterwards, the filtrate was treated with anhydrous sodium sulfate and concentrated under a stream of dry nitrogen at 30°C. The nitrosamines were analyzed by HPLC with a precolumn... 

The silver(I) sulfide precipitates out of solution and can be filtered and purified by washing with hot water. 

The free-radical polymerizations of the monomers were carried out in test tubes. In the glovebox, each methacrylate monomer (10 wt%) and the initiator ACHN (1 part intitiatorilO parts monomer) was dissolved in toluene and loaded into a test tube. Then the tubes were moved out of the glovebox and were gradually heated under nitrogen purge to 120 C to initiate the reaction in a hot oil bath. The polymerization system remained above 80 °C for 8 hrs. Each polymer was then precipitated in a large volume of methanol, filtered and purified by reprecipitation fi-om THF solution into methanol. 

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